TY - Generic T1 - Evaluating the Snow-Wildfire Relationship Using an Ensemble of Snowpack Observations T2 - 88th Annual Western Snow Conference Y1 - 2021 A1 - Alex Gottlieb A1 - Justin Mankin KW - climate change KW - ensembles KW - Snow water equivalent KW - wildfire AB -

Wildfire activity in the United States has increased in recent decades, with documented rises in the number of large fires, burned areas, and the length of the fire season (Westerling, 2016). Fires contribute to carbon emissions, widespread forest mortality, and human morbidity and mortality by posing a direct hazard and from degrading air quality. Wildfire increases are thought to be a product of several interacting factors, including human settlement in fire-prone areas, a legacy of fire suppression, as well as favorable fire weather partly attributable to anthropogenic climate change (Abatzoglou and Williams, 2016). As such, a deeper understanding of the geophysical drivers of wildfire activity can both improve its seasonal predictability and inform expectations about future wildfire under continued warming.

JF - 88th Annual Western Snow Conference CY - Bozeman, MT UR - /files/PDFs/2021Gottlieb.pdf ER - TY - Generic T1 - The Effect of Forest Structure on Snowpack Along Arizona's Mogollon Rim T2 - 86th Annual Western Snow Conference Y1 - 2018 A1 - Patrick Broxton A1 - Willem J.D. van Leeuwen A1 - Joel Biederman KW - Airborne LiDAR KW - Arizona KW - Forest Structure KW - Modelling KW - SWE JF - 86th Annual Western Snow Conference CY - Albuquerque, New Mexico UR - /files/PDFs/2018Broxton.pdf ER - TY - Generic T1 - Extremes of Opportunity: Examining Recent Trends in Warm Season Extreme Precipitation for New Mexico River Basins T2 - 86th Annual Western Snow Conference Y1 - 2018 A1 - Maryam Pournasiri Poshtiri A1 - Erin Towler A1 - Dagmar Llewellyn A1 - Andreas F Prein AB -

We explore recent trends in precipitation characteristics within the state of New Mexico and southern Colorado, relevant to the Rio Grande and Pecos basins, where increasing temperatures and decreasing snowpack threaten to reduce the water available for storage and use. To determine how changing precipitation could potentially help to mitigate decreasing water supply, we examine both magnitude and frequency of daily precipitation characteristics for the warm season (June - October) and individual months therein, with a focus on the upper quantiles and extremes within the period 1981 to 2017. We find that the dominant sign of the precipitation trend depends on the season/month examined. Negative trends dominate the warm season, June, and August, while positive trends dominate July and for some September indicators. However, the majority of locations in the study area did not show any significant trends. The increasing trends for the July indicators show the most potential for water supply, with the location of these significantly positive trends mainly concentrated in the southeastern and eastern part of the study region. The frequency of days above the 99th daily precipitation quantile for September also shows increasing trends at some southern and southeastern locations, but this heavy precipitation could be difficult to capture for water supply. However, across most characteristics examined, we find that significant trends are more detectable in the frequency indicators than in the magnitude indicators. As such, for times and locations showing increasing trends, this suggests that water managers looking to exploit changes in precipitation might not need to plan for larger events, but rather for more frequent events. (KEYWORDS: decreasing snowpack, extreme precipitation, warm season, trends, New Mexico)

JF - 86th Annual Western Snow Conference CY - Albuquerque, New Mexico UR - /files/PDFs/2018Poshtiri.pdf ER - TY - Generic T1 - Effect of the Tree Canopies in Microwave Radiometric Remote Sensing of Snowpack T2 - 85th Annual Western Snow Conference Y1 - 2017 A1 - Seyedmohammad Mousavi A1 - Roger De Roo A1 - Kamal Sarabandi A1 - Anthony W. England AB -

Effective management of the freshwater reservoir requires almost daily monitoring the spatial and temporal
distribution of the snow water equivalent (SWE) and snowpack wetness. Both microwave radar and radiometers
systems have long been proposed and implemented as powerful remote sensing tools in retrieving the physical
parameters of interest due to their all-weather operation capability. In case of microwave radiometry, microwave
remote sensing of dry snowpack is based on frequency-dependent differential scattering by the ice grains in the
snowpack, referred to as scatter darkening. Scatter darkening has been developed as a SWE remote sensing
technology over the last three decades. However, the presence of tree canopies in a given scene can affect the SWE
estimation of snowpack. Hence, the knowledge of the brightness temperature of tree canopies is important in order
to better predict and recover the SWE of the snowpack. We have used the microwave radiometers at three different
frequencies; namely, 1.4 GHz, 19 GHz, and 37 GHz, mounted on our boom truck to look at the snowpack. The
measurements have been done in Grand Mesa National Forest in Colorado as the NASA SnowEx campaign in Feb
2017. In this paper, the effect of the snow on tree canopies on their brightness temperature is discussed. Moreover,
the elevation angular dependence of the brightness temperature of the tree canopies is investigated.

JF - 85th Annual Western Snow Conference CY - Boise, Idaho UR - /files/PDFs/2017Mousavi.pdf ER - TY - Generic T1 - Estimating Snowmelt Contribution from the Gangotri Glacier Catchment into the Bhagirathi River, India T2 - 84th Annual Western Snow Conference Y1 - 2016 A1 - Rodney M. Chai A1 - Leigh A. Stearns A1 - C. J. van der Veen AB -

The Bhagirathi River emerges from the terminus of the Gangotri Glacier at 4000 m.a.s.l., and is a major tributary of the Ganges River. The Ganges is the world’s third-largest river by discharge and provides water to over 350 million people in India and Bangladesh. The discharge of the Bhagirathi, which is driven by seasonal snow cover and melt, therefore has significant impacts on the downstream water supply to a population larger than the United States. Discharge data are scarce along the Ganges River, particularly in the headwaters. The Snowmelt Runoff Model (SRM) is a simple temperature index model that uses relatively few parameters to model runoff. This makes it ideal in remote areas like the Himalayas where it is difficult to get on-the-ground data that an energy balance model would require.  A digital elevation model was used to divide the basin into elevation bands, and MODIS tiles were used to determine snow-covered area for 2010 and 2011. The results show that of the three SRM parameters, SCA showed the strongest correlation with both observed and modeled discharge in 2010, with R2 values of 0.64 and 0.56 respectively. In 2011, however, all three SRM parameters performed poorly with both observed and modeled discharge.  (KEYWORDS:  SRM, Gangotri glacier, snow covered areas, Ganges River)

JF - 84th Annual Western Snow Conference CY - Seattle, Washington UR - /files/PDFs/2016Chai.pdf ER - TY - Generic T1 - An Evaluation of Terrain-Based Downscaling of MODIS-Based Fractional Snow- Covered Area Datasets Over the Tuolumne River, CA, Based on LiDAR-Derived Snow Data (Extended Abstract) T2 - 84th Annual Western Snow Conference Y1 - 2016 A1 - Nicoleta C. Cristea A1 - Jessica D. Lundquist AB -

Remotely-sensed snow covered area (SCA) datasets with both high spatial and temporal resolutions are needed for research, planning, and management of hydrologic and ecologic resources. MODIS-based products provide good temporal resolution (daily), but on coarse scale grids (~463 m). This coarse spatial scale can be refined through applying downscaling procedures, which consist of using the fractional snow cover area product (fSCA, the percentage snow cover within a MODIS pixel area) to assign binary (presence/absence) SCA data on higher resolution grids. Current methods rely on representing ablation effects on snow spatial variability by using topographic radiation-derived slope factors and relative elevation as primary indicators of snow presence/absence (Walters et al., 2015), or a degree-day approach (Li et al., 2015). In both studies satellite-derived data were utilized for model input and validation. Uncertainty associated with the input and validation data in assessing downscaling performance could be better understood if reliable, platform-independent fine scale SCA data were available. Here, we propose such a framework for testing and developing a new downscaling procedure based on LiDAR-derived snow depth data collected over the Tuolumne River watershed, CA. Our new downscaling procedure is based on terrain-derived indices that are representative of both ablation and accumulation, drivers of snow spatial variability in complex terrain. The use of the LiDAR-derived dataset has several advantages over using the satellite data. First, the validation data is more accurate, as LiDAR-derived data are high resolution (1-3m). Second, accurate fSCA datasets can be derived from the high resolution LiDAR-derived snow data at the MODIS scale to be used as input data. Third, the downscaling performance can also be tested over vegetated areas, where LiDAR-derived data is presumably more accurate than the satellite data.

JF - 84th Annual Western Snow Conference CY - Seattle, Washington UR - /files/PDFs/2016Cristea.pdf ER - TY - Generic T1 - The Effect of the Vertical Canopy Structure on Snow Processes Scenarios: Simulations of the Vertical Resolved Energy Fluxes and Snow Using a Higher-Order Closure Multi-Layer Soil-Vegetation-Atmospheric Model T2 - 84th Annual Western Snow Conference Y1 - 2016 A1 - Laura McGowan A1 - Kyaw Tha Paw A1 - Helen Dalhke A1 - Shu-Hua Chen A1 - David Pyles AB -

Snow cover is a critical driver of the Earth’s surface energy budget, climate change, and water resources. Variations in snow cover not only affect the energy budget of the land surface but also represent a major water supply source. In California, US estimates of snow depth, extent, and melt in the Sierra Nevada are critical to estimating the amount of water available both California agriculture, urban and environmental users. However, accurate estimates of snow cover and snowmelt processes in forested areas still remain a challenge. Canopy structure influences the vertical and spatiotemporal distribution of snow, and therefore ultimately determines the degree and extent by which snow alters both the surface energy balance and water availability in forested regions. In this study we use the Advanced Canopy Atmosphere Soil algorithm (ACASA), a multilayer soil vegetation atmosphere numerical model, to simulate the effect of different snow covered canopy structures on the energy budget, water budget, temperature and other scalar profiles within different forest types in the Sierra Nevada, California. ACASA incorporates a higher order turbulence closure scheme which allows the detailed simulation of turbulent fluxes of heat and water vapor as well as the CO2 exchange of the within canopy layers. As such ACASA can capture the counter-gradient fluxes within canopies that may occur frequently, but are typically unaccounted for, in most snow hydrology models. Four different canopy types were modeled ranging from bottom heavy canopies with most of the biomass located near the ground to top heavy canopies with most of the biomass located near the top of the canopy. Preliminary results indicate that the canopy stand structure associated with the different canopy types fundamentally influence the vertical scalar profiles (including those of temperature, moisture, and wind speed) in the canopy and thus alter the interception and snow melt dynamics in the forested land surfaces. The differences in the vertical scalar profiles resulted in over one week difference in the complete melt of the seasonal below canopy snowpack between canopy types in high-snow scenarios. In addition, the turbulent transport dynamics, including counter-gradient fluxes are discussed in the context of the snow energy balance and potential misattribution of water sources within the vertical canopy that could occur when counter-gradient fluxes are not considered.  (KEYWORDS:  snow, canopy interception, turbulence, counter-gradient fluxes)

JF - 84th Annual Western Snow Conference CY - Seattle, Washington UR - /files/PDFs/2016McGowan.pdf ER - TY - Generic T1 - Exploring the Impacts of Reduced Snowpack Due to Light Absorbing Aerosols in Snow, Including Potential Influence on Wildfires T2 - 84th Annual Western Snow Conference Y1 - 2016 A1 - Catalina M. Oaida A1 - Yongkang Xue A1 - Thomas H. Painter AB -

The mountain snowpack is an essential resource for both the environment as well as society. Recent studies have shown light-absorbing aerosols (LAA) in snow such as desert dust and black carbon to be important players in surface energy and water budgets of mountain areas across Western United States (WUS). The presence of LAA in snow, by shifting snowmelt timing, can have an impact on soil and vegetation conditions in subsequent months. Based on historical data, strong correlations were found between snowmelt timing and wildfire activity, with the suggestion that a shorter snow season can lead to drier soil and vegetation conditions, which implies greater opportunities for wildfires. In this study, we aim to investigate the impact of a reduced snowpack and earlier snowmelt due to LAA in snow on wildfire risk across various regions of WUS, including the Cascade, Sierra Nevada, and southern Rocky Mountains.  To achieve this goal, we employ a regional climate model with a physically-based snow scheme that accounts for presence of LAA in snow. By comparing the LAA-loaded and LAA-free simulations over 10 years, we explore the changes induced by LAA to the water balance, as well as potential implications to wildfires. (KEYWORDS: dust and black carbon in snow, runoff changes, regional climate modeling, western United States, hydrologic cycle, wildfire risk)

JF - 84th Annual Western Snow Conference CY - Seattle, Washington UR - /files/PDFs/2016Oaida.pdf ER - TY - Generic T1 - Estimating Snow Water Equivalent at NWS Climatological Stations T2 - 81st Annual Western Snow Conference Y1 - 2013 A1 - Farnes, Phillip KW - density KW - precipitation KW - Snow water equivalent KW - snowmelt KW - temperature AB -

Typically, National Weather Service (NWS) Climatological Stations measure snow depth but not snow water equivalent (SWE). However, SWE is generally more important than depth when used in hydrologic and wildlife studies. Typically, there are higher elevation stations that measure SWE but lower elevations stations are predominately Climatological stations that do not measure SWE. New snowfall densities are generally between 6 and 10 percent while snow packs can reach densities into the 25 to 35 percent range just prior to and during melt. As part of developing the climatic database for the core area of the Greater Yellowstone Area (GYA), daily SWE was computed for all Climatological Stations. Some of these stations have snow courses at or near the station. Also, snow measurements were made at some of these stations in conjunction with the Snow Sinking Studies on the Northern Range of Yellowstone National Park. Methods for computing daily SWE using snow depth, precipitation and temperature will be presented as well as comparisons between estimated SWE and measured SWE at ten stations. The lengths of records where both measured and estimated SWE exist vary from about 17 years up to about 75 years. Long range trends of SWE will be shown for stations with longer records.

JF - 81st Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/2013Farnes.pdf ER - TY - Generic T1 - The Effect of Physiographic Parameters on the Spatial Distribution of Snow Water Equivalent in A Large Mountainous Basin T2 - 81st Annual Western Snow Conference Y1 - 2013 A1 - Wetlaufer, Karl A1 - Hendrikx, Jordy A1 - Challender, Stuart A1 - Marshall, Lucy AB -

Water accumulated and stored is the winter snowpack throughout the mountainous regions of the Western United States is a critical, yet poorly understood resource. An improved understanding of the correlations between basin physiography (e.g. elevation, land cover, incoming solar radiation, etc.) and snow water equivalence (SWE) in large and diverse landscapes could lead to better estimates of the total volume of water stored in the winter snowpack. This study quantifies the effect of the physiography of a large (207 km2) and complex mountainous basin (West Fork of the Gallatin River basin in SW Montana) on the spatial distribution of SWE and snow density. Sampling took place near the time of peak SWE accumulation (~April 1st 2012).

JF - 81st Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/2013Wetlaufer.pdf ER - TY - CONF T1 - Effects of Temperature on the Propylene Glycol/Ethanol (PGE) Solutions Used in Mountain Precipitation Gauges with the Polysorbate Emulsifier Additive T2 - 80th Annual Western Snow Conference Y1 - 2012 A1 - Lea, Rowyn A1 - Lea, Jon A1 - Lea, Jolyne KW - NRCS KW - precipitation gauge KW - propylene glycol/ ethanol (PGE) KW - SNOTEL AB -

The object of this study was to verify the earlier test to determine the temperatures at which various dilutions of equal proportions of propylene glycol and ethanol (PGE) with the addition of an emulsifier Polysorbate 20 (brand name Tween 20) would freeze. Earlier tests were conducted with straight mixture of 50 percent by volume of propylene glycol and 50 percent ethanol by volume without an emulsifier. This repeat study was to determine if the Tween 20 emulsifier had an effect on the freezing properties and specific gravity as tested in the earlier experiment. This experiment was also to observe if the 3 percent by volume Tween 20 would keep the 48.5 percent by volume propylene glycol and 48.5 percent by volume ethanol solution from separating at high temperatures which could occur at the remote site locations.

JF - 80th Annual Western Snow Conference PB - Omnipress CY - Anchorage, Alaska UR - sites/westernsnowconference.org/PDFs/2012Lea-R.pdf ER - TY - Generic T1 - Effect of Snow Covered Area and Delayed Snowmelt on Water Quality and Reservoir Management: 2010 Turbidity Event in Hetch Hetchy Reservoir T2 - 79th Annual Western Snow Conference Y1 - 2011 A1 - Mazurkiewicz, A.B. A1 - McGurk, B.J. A1 - Tsang, M. KW - Tuolumne River, turbidity, reservoir operation, hydrodynamic mixing, Hetch Hetchy Reservoir AB - The hydrodynamic processes in reservoirs located in snowmelt-dominated watersheds are poorly understood during snowmelt runoff. Very large storm events or unusually large spring inflows can threaten the operational and regulatory water quality goals. Turbidity levels in Hetch Hetchy are typically between 0.1 and 0.3 NTU, but storm events or unusual spring inflow events can produce inflow turbidity of over 15 NTU. This study collected turbidity and temperature data over a two-week period that included the peak inflow during an unusually large inflow event that carried a significant volume of sediment and organic debris-laden water, causing localized reservoir turbidities in excess of 10 NTU. The field data provided the information needed for operational responses and averted exceeding turbidity thresholds. An operator can adjust the elevation of the inlet used to release excess water as well as adjust the inlet elevation of water supplied to the customers. The operator can also manage reservoir storage to maintain a storage volume to dilute turbid inflow, and the timing of the release of excess water can be adjusted to control the location of mixing and control the approach of plumes of turbid water toward the water supply inlet. By combining inflow forecasts with real-time water quality data collection and dam operations, most snowmelt inflow turbidity events can be managed so that interruptions in supply due to water quality issues can be avoided. JF - 79th Annual Western Snow Conference T3 - Proceedings of the 79th Annual Western Snow Conference PB - Western Snow Conference CY - Stateline, NV UR - sites/westernsnowconference.org/PDFs/2011Mazurkiewicz.pdf ER - TY - Generic T1 - Exploring the Potential for a Fused Landsat-MODIS Snow Covered Area Product T2 - 79th Annual Western Snow Conference Y1 - 2011 A1 - Selkowitz, D. KW - Rocky Mountains, Colorado, Landsat, MODIS, snow covered area, remote sensing AB - Results from nine 3 x 3 km study areas in the Rocky Mountains of Colorado, USA demonstrate there is potential for using sporadically acquired Landsat images in combination with daily coarse resolution fractional snow covered area (SCA) images to produce daily high resolution binary SCA images. The results also highlight several challenges to implementing this type of approach. The approach described here consistently yields accurate results in locations with persistent winter and spring snow cover where ten or more partially snow covered images are available to populate the image database, but is less successful in areas with shallower or more ephemeral snow covers or when fewer images are available to populate the image database. This work represents a first step towards developing an algorithm to combine Landsat and MODIS data to produce daily 30 m resolution binary SCA images. Further research should focus on testing the accuracy of this approach across a range of landscape types and snow cover regimes, developing methods to improve prediction accuracy when snow cover is nearly complete or nearly absent, and developing methods to compensate for the effects of canopy cover on SCA retrievals. JF - 79th Annual Western Snow Conference T3 - Proceedings of the 79th Annual Western Snow Conference PB - Western Snow Conference CY - Stateline, NV UR - sites/westernsnowconference.org/PDFs/2011Selkowitz.pdf ER - TY - Generic T1 - Estimated Residence Time of Two Snowmelt Dominated Catchments, Boulder Creek Watershed, Colorado T2 - 78th Annual Western Snow Conference Y1 - 2010 A1 - Cowie, R A1 - Williams, M. A1 - Caine, N. A1 - Michel, R. KW - Boulder Creek, isotopic tracers, residence time, flowpaths, groundwater, Niwot Ridge AB - Delta-O-18 and 3-H (tritium) measurements of precipitation and stream waters from 2002 to 2009 were used as isotopic tracers to investigate residence times in two headwater catchments within the Boulder Creek Watershed in the Front Range of Colorado. The 225--ha Green Lake 4 alpine catchment and the adjacent 664--ha Como Creek subalpine catchment are established research sites for both the Niwot Ridge Long Term Ecological Research Network and Boulder Creek Critical Zone Observatory Network. The Green Lake 4 catchment had a mean residence time of 1.12 years while the Como Creek catchment had a mean residence time of 1.8 years. Tritium levels in Green Lake 4 were consistently similar to that of incoming precipitation indicating little exponential decay and indicative of shallow flowpaths and short residence times. Como Creek tritium levels were also close to incoming precipitation during spring and summer snowmelt with elevated levels appearing during baseflow indicating some contribution of bomb Spike waters likely being delivered from deeper flowpaths with longer residence times. These results indicate that headwater catchments within Boulder Creek Watershed have relatively short mean groundwater residence times with the potential for older groundwater contributions during low flow conditions in the sub-alpine. JF - 78th Annual Western Snow Conference T3 - Proceedings of the 78th Annual Western Snow Conference PB - Western Snow Conference CY - Logan, UT UR - sites/westernsnowconference.org/PDFs/2010Cowie.pdf ER - TY - Generic T1 - An Experimental and Modeling Investigation of the Impact of Silvicultural Manipulation on Snow Hydrology in the Cedar River Watershed, WA T2 - 78th Annual Western Snow Conference Y1 - 2010 A1 - Forsyth, J. A1 - Lundquist, J. A1 - Wayand, N. KW - Snow water equivalent, seasonal runoff, runoff timing, timber harvest effects, Cedar River AB - Over the past 80 years, forest harvesting throughout the western U.S. has resulted in a shift in the dominant forest structure to young, dense forests. Meanwhile, declining trends in mountain snow water equivalent (SWE), summer river flow, and earlier snowmelt have largely been attributed to climate with little consideration of the impact of the concurrent changes in vegetation from forestry practices. Silvicultural manipulation has the potential to increase snow water storage, change snowmelt timing and restore ecological processes that might normally be adversely affected by climate change. This study is primarily concerned with snowmelt timing, since it is crucial to watershed management in basins with limited reservoir storage. Any delay in snowmelt from silvicultural manipulation could reduce winter flood hazards and increase summer runoff when water demand for cities and agriculture is the highest. This study commenced in the 2009 water year and takes place in the Cedar River Watershed, WA, located in the climate-sensitive intermittent snow zone. Using a combination of distributed field measurements and point and distributed hydrologic models, we are investigating i) the heterogeneity of snow accumulation and melt in different forest structures, and ii) which forest changes are of comparable magnitude to climate change in their effects on snow hydrology. JF - 78th Annual Western Snow Conference T3 - Proceedings of the 78th Annual Western Snow Conference PB - Western Snow Conference CY - Logan, UT UR - sites/westernsnowconference.org/PDFs/2010Forsyth.pdf ER - TY - Generic T1 - Elevational Differences in Snowpack Variability: A Case for Increased Monitoring In the Olympic Mountains T2 - 78th Annual Western Snow Conference Y1 - 2010 A1 - McDonald, S. A1 - Barry, D. KW - Dungeness Creek, snowpack variability, climate change, Olympic Mountains, rain on snow, streamflow modeling AB - Climate change projections indicate that snowpack could be most affected at mid-elevations due to an increase in rain-on-snow events. For the past three winters, we collected snow and meteorological data from eleven snow courses and six remote mini-meteorological stations in the Dungeness watershed of the Olympic Mountains in western Washington. We compared our mid-elevation snow and weather data with data collected from the Dungeness SNOTEL over the same period. Most of our snowpack data do not correlate well with SNOTEL data, and temperature and relative humidity readings from our stations suggest that there are additional site and elevational differences that suggest that the existing SNOTEL site does not capture the range of variability within the watershed. Our findings indicate that increased permanent monitoring (e.g., by new SNOTEL sites) of snowpack in the Dungeness watershed as well as throughout the rain-on-snow elevation areas of the Pacific Northwest would improve our understanding of potential climate change influences on snowpack at all elevations, improve spatially-explicit snowpack and streamflow modeling efforts, and support improvements in water resources forecasting and management. JF - 78th Annual Western Snow Conference T3 - Proceedings of the 78th Annual Western Snow Conference PB - Western Snow Conference CY - Logan, UT UR - sites/westernsnowconference.org/PDFs/2010McDonald.pdf ER - TY - Generic T1 - Evaluating Snowmelt Modeling Methods of Different Complexities at a Watershed in the Canadian Rockies T2 - 77th Annual Western Snow Conference Y1 - 2009 A1 - Singh, P.R. A1 - Gan, T.Y. A1 - Gobena, A.K. KW - Canadian prairie, snowmelt, modeling, MacKenzie River, energy balance AB - Three snowmelt models of different degrees of model complexity and data requirement were used to simulate snow accumulation and ablation processes for a watershed in the Canadian Prairies. Results show that modifying the popular temperature index method by incorporating near-surface soil temperature as an additional predictor to air temperature could considerably improve the model performance. In addition, the modified method could achieve hourly simulation results that are comparable to a physically based energy balance method. Majority of the improvement in the modified temperature index method occurs when the melt rate is varied as a function of near-surface soil temperature. JF - 77th Annual Western Snow Conference T3 - Proceedings of the 77th Annual Western Snow Conference PB - Western Snow Conference CY - Canmore, AB UR - sites/westernsnowconference.org/PDFs/2009Singh.pdf ER - TY - Generic T1 - Effects of Mountain Pine Beetles and Timber Harvesting on Stand Attributes and Snow on the B.C. Interior Plateau T2 - 77th Annual Western Snow Conference Y1 - 2009 A1 - Teti, P. KW - forest harvest KW - Pine beetle KW - snowpack reduction KW - timber harvesting AB -

Considerable progress has been made in describing the effects of clearcut harvesting and reforestatation on snow accumulation and melt relative to mature healthy forests. However, in the aftermath of the recent mountain pine beetle infestation in B.C., the effects of harvesting beetle-killed pine stands need to be compared with what would have happened if the killed stands had been allowed to develop naturally. This paper reports on a project in which snow accumulation and ablation were compared in recent clearcuts, partially recovered plantations, and in natural pine stands at different stages of disturbance and recovery. SWE and ablation rates in treed plots were standardized by calculating ratios of SWE and ablation rates in treed plots to those in nearby clearcuts. SWE ratios were > 1 in only 3 of the 19 treed plots - a recently-defoliated stand and two plantations under 15 years old. Snow ablation ratios were > 1 only in a 15 year-old plantation. SWE ratios and ablation ratios in plantations and killed pine stands were analyzed as functions of time since disturbance. Results suggest that harvesting recently-killed pine stands could increase the rate of snowmelt for 15 to 25 years on the B.C. Interior Plateau.

JF - 77th Annual Western Snow Conference T3 - Proceedings of the 77th Annual Western Snow Conference PB - Western Snow Conference CY - Canmore, AB UR - sites/westernsnowconference.org/PDFs/2009Teti.pdf ER - TY - Generic T1 - Effect of Snowpack Changes in the Central Sierra Nevada on Water Supply Forecasts in the Truckee River Basin T2 - 76th Annual Western Snow Conference Y1 - 2008 A1 - Lea, J. KW - Runoff forecasting, snow accumulation timing, Donner Summit, declining snowpack, water supply AB - Water supply forecasts rely on a historic record of precipitation, snow and streamflow. The snowpack in the central Sierra Nevada has been measured each year since the early 1900s. Currently the USDA Natural Resources Conservation Service and the California State Cooperative Snow Survey program measure snow in the Sierra Nevada and keep long term records of the snowpack. These long-term records are a good indicator of seasonal precipitation in the building of the snowpack in the region. A statistical analysis of the snowpack record at Donner Summit compared to Tahoe City precipitation reveals a shift in the relation that occurred in the late 1970s. This change in the relation of the April 1 snow and cumulative seasonal precipitation in the area is statistically significant at the 99.9% level. Since the late 1970s, there no trend has been observed in annual precipitation amounts and annual streamflow volume on the Truckee River. However a decrease in the amount of cumulative snowpack on April 1 in comparison to the seasonal precipitation of October through March between these two sites has been observed. This indicates that from 1980 to 2007 there has been more rain than snow compared to the previous 43 years. JF - 76th Annual Western Snow Conference T3 - Proceedings of the 76th Annual Western Snow Conference PB - Western Snow Conference CY - Hood River, OR UR - sites/westernsnowconference.org/PDFs/2008Lea.pdf ER - TY - Generic T1 - Embedded Sensor Network Design for Spatial Snowcover T2 - 76th Annual Western Snow Conference Y1 - 2008 A1 - Rice, R. A1 - Bales, R. KW - Sensor network, snow accumulation, Yosemite, snow deposition, SWE AB - Scaling point observations of snow water equivalent (SWE) to model grid-element scales is particularly challenging given the considerable sub-grid variability in snow accumulation over complex terrain. In an effort to capture this sub-grid variability and provide spatially explicit ground-truth snow data an embedded snow sensor network was designed and installed in Yosemite National Park. Extensive snow surveys were used to guide the installation of the network and to relate the observations to more detailed spatial SWE fields. Four years of continuous spatial and temporal data from both Yosemite National Park indicate that accumulation and ablation rates can vary as much as 50% based on variability in topography and vegetation. These snow distribution patterns are especially apparent in the open forests where vegetation structure largely controls variability in snow distribution. Comparisons with historical snow course data shows that a single point measurement is a poor estimator of snow depth over a homogenous area, but 4 or more measurement points can reduce the uncertainty by 50%. Further analyses indicated that an optimal snow depth network consists of 7 to 10 snow depth sensors. JF - 76th Annual Western Snow Conference T3 - Proceedings of the 76th Annual Western Snow Conference PB - Western Snow Conference CY - Hood River, OR UR - sites/westernsnowconference.org/PDFs/2008Rice.pdf ER - TY - Generic T1 - Enhancing Stream Forecast Modeling in California Mountain Watersheds T2 - 76th Annual Western Snow Conference Y1 - 2008 A1 - Shupe, J. A1 - Potter, C. A1 - Klooster, S. KW - Ecosystem model, CASA, HYDRA, runoff prediction, snowmelt, Merced River AB - This study describes research using the NASA Ames version of the Carnegie-Ames-Stanford Approach (CASA) ecosystem model coupled with a surface hydrologic routing scheme called the Hydrological Routing Algorithm (HYDRA) to model the system of California watersheds. To assess CASA-HYDRA's ability to estimate actual water flows in both extreme and non-extreme precipitation years, we have compared the gridded model results on a monthly time scale with gage station data throughout the state. Considering the importance of the snow pack to the state's water regime, we are particularly interested in CASA-HYDRA's performance in California's mountain watersheds. Consequently, we made additional comparisons between our model and results generated from the USDA Snowmelt Runoff Model (SRM) applied to the Merced River watershed in Yosemite, CA. The results of both comparisons highlighted the need to enhance CASA-HYDRA's snowmelt algorithm. The efficacy of the degree-day approach has been demonstrated by the consistently solid performance of the SRM, so we have integrated this algorithm into CASA-HYDRA. JF - 76th Annual Western Snow Conference T3 - Proceedings of the 76th Annual Western Snow Conference PB - Western Snow Conference CY - Hood River, OR UR - sites/westernsnowconference.org/PDFs/2008Shupe.pdf ER - TY - Generic T1 - Estimating Forage Production and Winter Severity on the National Elk Refuge, Jackson, WY T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Cole, E.K. A1 - Farnes, P.E. KW - National Elk Refuge, Jackson, elk, temperature, SWE, forage, Index of Winter Severity AB - Each October through November, elk and bison migrate to the National Elk Refuge (NER) near Jackson, WY to feed on native forage produced on the Refuge. Usually by late January, standing forage has been utilized or becomes unavailable because of snow and ice, and NER staff then supplies supplemental feed in the form of alfalfa pellets. For the past 34 years, NER staff has estimated total annual forage produced on the Refuge by clipping vegetation within different plant community types. Keetch Byram Drought Index (KBDI), and growing degree-days (GDD) based on daily average temperature threshold of 5 deg C have been calculated daily for Jackson and Moose climatological stations since 1949. Also, daily snow water equivalent (SWE) has been estimated for these stations using climatological records. Critical temperatures (-18 deg C for elk) have been summarized using departure from daily minimum temperatures. SWE, forage production, and critical temperatures are weighted and combined to determine Index of Winter Severity (IWS) for elk and bison. Methods for calculating the IWS for elk and bison and how the IWS is used for Refuge operations will be presented. Average KBDI for different accumulations of GDD and spring precipitation are compared to production of grass and forbs on 34 different plant community groups. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Cole.pdf ER - TY - Generic T1 - Estimating Average Annual Runoff from Montana Streams T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Farnes, P.E. KW - Runoff prediction, Montana, SNOTEL, precipitation, cover type, fire history AB - Procedures for estimating runoff from un-gaged streams will be presented. First and most important is to have an accurate average annual precipitation map for the current base period. The precipitation map needs to be based on a maximum elevation grid of 500 meters and preferably a 100 to 200 meter grid. It needs to be based on a procedure that looks at the nearest two or three neighbors and one that assigns measured values to measured points. The Montana SILC3 Land Cover Classification provides the cover types for most areas. Some of the 36 different cover types that have similar hydrologic responses can be combined for hydrologic analysis. Data from SNOTEL sites and climatological stations in the area was used to determine the relationship between average annual precipitation, average April 1 snow water equivalent, and average April through July precipitation for the current base period. Average annual precipitation and runoff from gaged streams in the area and percent forested area for each gaged watershed are used to determine a runoff vs. precipitation curve for drainages if all of the forest was removed. By applying factors from the cover type vs. forest species age curves, the runoff was determined for the area of each cover type in each precipitation zone. These were accumulated to determine runoff for each watershed or HUC of interest. Using fire history or logging by decades, usually available from land managing agencies, it was possible to determine changes in runoff by decade from any given watershed. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Farnes.pdf ER - TY - Generic T1 - Evaluation of Streamflow Forecasts for Multiple Basins in the Pacific Northwest Using an Enhanced Version of the Snowmelt Runoff Model T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Harshburger, B.J. A1 - Moore, B.C. A1 - Blandford, T.R. A1 - Humes, K.S. A1 - Walden, V.P. KW - Snowmelt runoff, streamflow forecasts, SRM, Downscaled forecasts, GFS AB - Runoff in mountainous areas of the Pacific Northwest is largely dominated by snowmelt. Thus accurate streamflow forecasts are critical for the management of water resource systems. The objective of this project is to develop a short to medium range streamflow prediction system (1 to 15 days) based on the Snowmelt Runoff Model (SRM) for mountainous basins in the Pacific Northwest. Enhancements were made to the model to optimize model efficiency and aid in its operational implementation. Results from retrospective forecast model runs, using statistically downscaled temperature and precipitation forecasts from the NCEP Global Forecasting System (GFS) model (2003-2006) will be examined. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Harshburger.pdf ER - TY - Generic T1 - An Engineering Design Study of Electronic Snow Water Equivalent Sensor Performance T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Johnson, G.B. A1 - Gelvin, A. A1 - Schaefer, G.L. KW - Snow sensor, SWE, CRREL, NRCS, Hogg Pass, freeboard AB - The USA ERDC CRREL and the USDA NRCS developed an electronic SWE sensor based on the results of field and theoretical studies of SWE pressure sensor performance. The CRREL/NRCS sensor is about 3 m square and is modular consisting of nine perforated panels, a center panel and eight outer surrounding panels that allow water to percolate through the sensor. Water percolation minimizes thermal differences between the sensor and surrounding soil and the eight surrounding panels act to buffer the center panel, where SWE is measured, from stress concentrations that develop along the perimeter of the sensor. Two years of field-tests (winters of 2005-2006 and 2006-2007) at Hogg Pass, OR, demonstrate that the CRREL/NRCS sensor's center panel accurately measures SWE variations even when stress concentrations are observed on the sensor's outer panels. During the first winter, stress concentrations occurred on the outer panels during periods of rapid snow settlement following large snow accumulations and when the rate of snowmelt at the sensor/snow interface was significantly different from the snowmelt rate at the soil/snow interface of the surrounding ground. SWE measurement performance is optimal when the sensor has no freeboard. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Johnson.pdf ER - TY - Generic T1 - Effects of Past and Future Climate Change on Ski Areas T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Mote, P.W. A1 - Casson, J. A1 - Hamlet, A.F. A1 - Reading, D. KW - Snow course, ski areas, temperature, snow depth, climate change AB - We examine USDA snow course data for ski areas during the ski season to determine the degree to which midwinter snow is statistically sensitive to temperature. For most of the 16 Northwest ski areas analyzed here, a reasonably strong negative partial correlation of mid-season snow depth with antecedent temperature indicates that further warming will have an impact on the quantity of snow. The effects of these physical changes on the profitability of a given ski area will depend in part on the adaptive capacity of the ski area. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Mote.pdf ER - TY - Generic T1 - Experimental Study on the Bond Destruction Between Snow/Ice and Anti-Freezing Pavements, Depending on Properties of Snow/Ice and Number Of Wheel Load Passes T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Takeichi, K. KW - Bond destruction, anti-freezing, pavement, snow, ice AB - The bond destruction between snow/ice and anti-freezing pavements is mainly assessed quantitatively by the relationships between bare pavement ratio (using computer image processing), the degree of scatter or stripping of snow/ice, the friction coefficient (u), and the number of wheel load passes. Results are compared with test results from the dense-graded asphalt pavement used as a control pavement. As for the snowpack, the bond-destruction and the increase of u are evaluated on the gum-rolled pavement that has a flexible surface texture under 100 to 500 passes at -5 deg C and 5 kN wheel load (200 kPa tire pressure). As a result of tests, the anti-freezing effects of anti-freezing pavements are evaluated and confirmed at -5 deg C. For the same tests and pavement but at -10 deg C, increased friction effects were found to be insufficient under the passenger car wheel load. Therefore, it is necessary in the future to develop a more effective hybrid type anti-freezing pavement (such as gum-rolled pavement combined with a deicing chemical in the asphalt mixture) to cause bond-destruction to all of snow/ice surfaces at -10 deg C. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Takeichi.pdf ER - TY - Generic T1 - Evaluation of Model Enhancements and Probabilistic Forecasting Techniques for The Snowmelt Runoff Model T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Harshburger, B.J. A1 - Moore, B.C. A1 - Blandford, T.R. A1 - Humes, K.S. A1 - Walden, V.P. A1 - Hruska, R. KW - Streamflow forecasts, ESP, SRM, Big Wood River Basin, antecedent temperature, forecast errors AB - Accurate streamflow forecasts are critical for the responsive management of water resource systems, which are designed and operated for the purposes of irrigation, flood control, and hydroelectric power generation. In the Western United States, water supplies are often derived form runoff due to snowmelt. The objective of this project is to develop an ensemble (probabilistic) prediction system for short to medium range streamflow forecasts (1 to 15 days). The hydrologic model used in this study is the Snowmelt Runoff Model (SRM), which is a conceptually-based model designed to simulate and forecast daily streamflow in mountain basins where snowmelt is a major contributor to runoff (Martinec et al., 1994). To optimize model efficiency and aid in its operational implementation, three enhancements have been made to the model. These enhancements are: 1) the use of an antecedent temperature index method to track snowpack cold-content and account for the delay in melt associated with diurnal refreezing, 2) the use of both maximum and minimum critical temperatures to partition precipitation into rain, snow, or rain/snow mixed, and 3) the stochastic modeling of forecast errors to generate streamflow ensembles, from which exceedence probabilities can be obtained. Results from retrospective model runs, using temperature and precipitation forecasts from NCEP GFS model (2000-2004) will be examined and used to identify the error in the streamflow forecasts. (Abstract only) JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006Harshburger.pdf ER - TY - Generic T1 - An Examination of External Influences Embedded in the Historical Snow Course Data of Utah T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Julander, Randall P. A1 - Bricco, M. AB -

Snowpack data collection has a long and storied history in Utah as well as the western United States. In Utah, records extend back to at least 1912. Systematic measurements began in the mid 1920's with many long-term snow courses established at that time. Each site was meticulously mapped, described and most important, photographed from several angles. Comparisons are made between the 1936 photographs, maps and descriptions and current conditions, specifically with regard to vegetation. General conclusions are made regarding the impact that vegetation change has had on snow accumulation at each course. With the advent of weather modification programs, changes in snow accumulation could reasonably be expected. Utah began a relatively small test weather modification program in the 1950's in central Utah. The Utah cloud seeding act was passed in 1973 and the seeding program has continued since that time. Snow Courses affected by this program are identified and the potential impact on historical data. The impact of sensor change from steel pillows to hypalon is discussed. Physical changes at data collection sites are estimated. Finally, recommendations for individual snow course suitability for long-term study based on consistency are made for each of the courses examined. SNOTEL sites, the automated version of the snow courses began to be installed in the late 1970's and early 1980's. These sites to a lesser degree due to the shorter historical time of data collection, have been impacted by vegetation change as well.

JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006JulanderB.pdf ER - TY - Generic T1 - Estimating the Quantity and Quality of Snow at the Aspen Ski Area for the Years 2030 and 2100 T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Lazar, B. A1 - Smith, J. A1 - Williams, M. KW - Climate change, Aspen Ski Area, decreased snowpack, emission scenarios, GCM, SRM AB - We evaluated how climate change resulting from increased greenhouse gas (GHG) emissions may affect the quantity of snow at Aspen Mountain ski area in 2030 and 2100. We modeled climate change using MAGICC/SCENGEN, and ran combinations of five general circulation models (GCMs) and three GHG emission scenarios. Snow quantity was evaluated using the Snowmelt Runoff Model (SRM), and a module developed to estimate snow quantity during the accumulation season, before snowmelt initiation. We used the five GCMs that best simulate current conditions, and three emission scenarios representing low, mid, and high emissions conditions. The date when snow starts to accumulate at the base area is delayed by six to seven days by 2030 and anywhere from 1.5 to 4.5 weeks by 2100. For mid-winter snows, a 15% increase in snowfall compensates for a 1.5°C increase in air temperature such that there was little change in snow depth. Snow depth goes to almost zero for the base area in 2100 under the medium GHG emission A1B scenario. In the high GHG emission A1F1 scenario, snow depth goes to near zero for the entire lower two-thirds of the mountain. The effect is substantially reduced under the low GHG emissions B1 scenario. JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006Lazar.pdf ER - TY - Generic T1 - An Evaluation of SNODAS for Determining Snow Water Equivalent on Mount St. Helens T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Lea, J. A1 - Reid, I. KW - Mt. St. Helens, floods, eruption, Toutle River, SNODAS, SNOTEL AB -

When Mount St. Helens erupted on May 18, 1980 melting snow and ice on the mountain enhanced a large debris flood wave from all sides of the mountain, creating exceptional flooding along the Toutle River in southwest Washington. Mount St. Helens became active again in September 2004. During both of these episodes there was considerable concern that another eruption would entrain the existing snowpack resulting in a devastating flood. The US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS), National Water and Climate Center (NWCC) was requested to provide weekly snow water equivalent (SWE) on Mount St. Helens to the National Weather Service Northwest River Forecast Center (NWRFC) and North Pacific Division of the US Army Corps of Engineers for determining potential flood magnitude in the event of an eruption. In the 1980s the snowpack was determined from the NRCS SNOTEL station network located around the mountain. SNODAS uses a physically based, spatially-distributed energy and mass-balance snow model in conjunction with assimilated satellite, airborne and ground-based observations of snow covered area and SWE to determine several snowpack parameters and modeled SWE at a 1 km grid scale national coverage. The SNODAS system is compared to the traditional SNOTEL method of determining the snowpack at three elevation bands and four quadrants on Mount St. Helens. SNODAS provides an improved model of the snowpack SWE around Mount St. Helens.

JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006LeaA.pdf ER - TY - Generic T1 - An Evaluation of the Spectral Mixture Analysis Applied to MODIS Data T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Mazurkiewicz, A.B. A1 - Callery, D.G. A1 - Nolin, A.W. KW - Snow covered area, SCA, satellite, MODIS, SWE, binary, fractional, mixture modeling, AB -

Satellite images of snow-covered area (SCA) have become increasingly useful tools in hydrologic and climatological studies. SCA images are used to help estimate snow water equivalence, a critical input variable for modeling in these fields. Two techniques have been used to map SCA from satellite data: 1) binary, which applies a snow/no-snow threshold to a normalized difference snow index and 2) fractional, which uses spectral mixture modeling. The objective of this work is to assess the differences between the MODIS SCA product and fractional SCA images computed using MODIS surface reflectance data, and identify the importance of vegetation correction. We compared SCA images at peak and mid-melt snowpack in two meso-scale watersheds with mixed land cover in the Pacific Northwest. The spectral mixture model estimated a much lower percent SCA at peak snowpack in comparison to the MODIS SCA images. During mid-melt, snow cover existed only in the forested upper portions of the basin. In this case, the mixture model and the standard MODIS image predicted similar amounts of SCA. At peak snowpack, the spectral mixture model calculated low SCA in forested areas above the snowline in both study basins. These results suggest that the spectral mixture modeling method, as applied here, is inadequate for identifying snow cover beneath a forest canopy where adjoining open areas are also snow-covered. For areas with a more homogeneous snow reflectance conditions, the current MODIS algorithm may estimate SCA as accurately as the spectral mixture method.

JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006MazurkiewiczB.pdf ER - TY - Generic T1 - Estimation of Snowmelt Runoff in the Poqueira River Basin (Province of Granada, Spain) Using SRM and MODIS Images T2 - 74th Annual Western Snow Conference Y1 - 2006 A1 - Rigueiro, G.V A1 - Giraldez, J.V A1 - Gonzalez-Dugo, M.P. A1 - Gomez-Landesa, E. A1 - Mateos-Iniguez, L. KW - Snowmelt runoff, Poqueira River, Spain, water supply, irrigation AB - In mountain basins, where part of the precipitation is snowfall, snowmelt runoff can be a significant contribution to the total river discharge. This is the case of the Poqueira River, in Southern Spain, a tributary of the Guadalfeo river in the southwestern slope Sierra Nevada, where snowmelt is the main water supply of an ancient irrigation system. The Mediterranean climate of the Poqueira basin is influenced by the relief, elevation, and proximity to the sea. The relief affects the entry of the western winds, the main cyclone track, inducing a great variability in the precipitation. The elevation is responsible for the snow fall that occurs even in middle of the Spring when temperatures at the sea coast are very mild. The snow usually accumulates during late Fall, Winter and early Spring. Snowmelt starts in Spring lasting until early Summer. In this paper we present a snow water resources evaluation which applies to Poqueira River basin in order to quantify the water availability for irrigation. The evaluation is based on the simulation of the snow fusion using the snowmelt runoff model (SRM) and satellite data that provide the snow cover distribution (Rango, 2003). JF - 74th Annual Western Snow Conference T3 - Proceedings of the 74th Annual Western Snow Conference PB - Western Snow Conference CY - Las Cruces, NM UR - sites/westernsnowconference.org/PDFs/2006Rigueiro.pdf ER - TY - Generic T1 - Evaluation of Gridded Snow Water Equivalent and Satellite Snowcover Products For Mountain Basins in a Hydrologic Model T2 - 73rd Annual Western Snow Conference Y1 - 2005 A1 - Dressler, K.A. A1 - Leavesley, G.H. A1 - Bales, R.C. A1 - Fassnacht, S.R. KW - PRMS, satellite snow cover, modeling, Rio Grande, Salt River, SNOTEL, AB - The USGS Precipitation Runoff Modeling System (PRMS) hydrologic model was used to evaluate experimental, gridded, 1-sq km snow covered area (SCA) and snow water equivalent (SWE) products for two headwater basins within the Rio Grande (i.e. upper Rio Grande River basin) and Salt River (i.e. Black River basin) drainages in the Southwestern United States. The SCA product was the fraction of each 1-sq km pixel covered by snow and was derived from NOAA Advanced Very High Resolution Radiometer imagery. The SWE product was developed by multiplying the SCA product by SWE estimates interpolated from National Resources Conservation Service Snow Telemetry (SNOTEL) point measurements for a six-year period (1995-2000). Measured SCA and SWE estimates were consistently lower than values estimated from temperature and precipitation within PRMS. Greatest differences occurred in the relatively complex terrain of the Rio Grande basin, as opposed to the relatively homogeneous terrain of the Black River basin where differences were small. Differences between modeled and measured snow were different for the accumulation period vs. the ablation period and had an elevational trend. (Abstract only) JF - 73rd Annual Western Snow Conference T3 - Proceedings of the 73rd Annual Western Snow Conference PB - Western Snow Conference CY - Great Falls, MT UR - sites/westernsnowconference.org/PDFs/2005Dressler.pdf ER - TY - Generic T1 - Evaluation of Enhancements to the Snowmelt Runoff Model T2 - 73rd Annual Western Snow Conference Y1 - 2005 A1 - Harshburger, B.J. A1 - Blandford, T.R. A1 - Humes, K.S. A1 - Walden, V.P. A1 - Moore, B.C. KW - SRM, Big Wood River, degree days, SNOTEL, rain-on-snow AB - As part of a larger effort to develop tools for improved short-term (1-2 week) streamflow forecasting in snowmelt-dominated basins, the Snowmelt Runoff Model (SRM) is used to simulate and forecast streamflow in the Big Wood River basin, Idaho. Several enhancements to SRM will be evaluated: a) a new method to estimate degree-days; b) new techniques used to assign and temporally update model parameters (degree-day factor and runoff coefficients) that make use of data from SNOTEL sites located within the basin and; c) the incorporation of relative humidity and wind speed data into a new (optional) model module designed to improve model performance during rain-on-snow events. Model results will be evaluated to determine the usefulness of these enhancements. JF - 73rd Annual Western Snow Conference T3 - Proceedings of the 73rd Annual Western Snow Conference PB - Western Snow Conference CY - Great Falls, MT UR - sites/westernsnowconference.org/PDFs/2005Harshburger.pdf ER - TY - Generic T1 - Evaluating the stuffblock and tilt board snowpack stability tests as snow avalanche forecasting tools T2 - 72nd Annual Western Snow Conference Y1 - 2004 A1 - Carter, P. A1 - Heavner, M. A1 - Hood, E. KW - Avalanche, avalanche forecasting, snowpack stability, stuffblock, tilt board AB - Snow avalanche forecasting relies on, among other factors, an assessment of snowpack stability derived from careful observation of snow cover stratigraphy. Snowpack profiles and stability tests provide quantifiable information about the location and strength of weak layers in the snowpack. This study found: 1) good comparative results between the stuffblock and compression tests and, 2) a relationship between tilt board test results in level study sites and skier-triggered avalanches. JF - 72nd Annual Western Snow Conference T3 - Proceedings of the 72nd Annual Western Snow Conference PB - Western Snow Conference CY - Richmond, B.C. UR - sites/westernsnowconference.org/PDFs/2004Carter.pdf ER - TY - Generic T1 - The Effect of Basin Scale on Diurnal Streamflow Timing T2 - 72nd Annual Western Snow Conference Y1 - 2004 A1 - Lundquist, J.D. A1 - Dettinger, M. KW - Streamflow timing, Tuolumne River, travel time, basin scale, diurnal flow AB - Hourly streamflow timing, as revealed by diurnal fluctuations in discharge in snowfed watersheds, provides a new tool for understanding transport times and processes in river basins. Travel time delays at different basin scales were measured in nested subbasins (6 to 775 km2) of the Tuolumne River in Yosemite National Park throughout the spring 2002 and 2003 melt seasons. The travel time increases with longer percolation times through deeper snowpacks, increases with longer travel times overland and along longer stream channels, and increases with slower in-stream flow velocities. In basins smaller than 30 km2, snow properties that determine the travel times through the snowpack dominate streamflow timing. In particular, daily peak flows shift to earlier in the day as the snowpack thins and mean discharge increases. In basins larger than 150 km2, snowpack heterogeneity and mixing cause the hour of peak flow to be remarkably consistent, with little or no variation due to snowpack properties. Basins with areas in between 30 and 150 km2 exhibit different characteristics in different years, illustrating the transition between small and large-scale basin characteristics. Increasing channel travel times as the snowline retreats to higher elevations are not enough to offset the observed decrease in mean snowpack travel times. JF - 72nd Annual Western Snow Conference T3 - Proceedings of the 72nd Annual Western Snow Conference PB - Western Snow Conference CY - Richmond, B.C. UR - sites/westernsnowconference.org/PDFs/2004Lundquist.pdf ER - TY - Generic T1 - Effects of small logged openings on snow ablation during a high snow year T2 - 72nd Annual Western Snow Conference Y1 - 2004 A1 - Teti, P. KW - Logging effect, snow ablation, Quesnel Highland, harvest treatments, ablation , peak streamflow AB - The effects of small logged openings on snow ablation rate were studied from 1994 through 1998 at a sub-alpine silvicultural systems research site in the Quesnel Highland of B.C. Six snow plots were in north-facing treatment units from which 21 to 34 percent of the forest had been previously harvested and one was installed in an unharvested control. One purpose was to determine the potential effects of group selection on peak streamflows in the event that this silvicultural system is applied over large areas. Average ablation rates in openings increased from 1.6 to 2.2 cm per day as opening diameters increased from 1 to 5 tree heights (1H to 5H). There was no significant effect of small openings on ablation rates in the adjacent trees. The net effect of harvesting 30 percent of the area in the form of 3H and 5H openings was that ablation rates increased by 5 and 13 percent respectively in a year with above-average snowmelt-generated peak streamflows. JF - 72nd Annual Western Snow Conference T3 - Proceedings of the 72nd Annual Western Snow Conference PB - Western Snow Conference CY - Richmond, B.C. UR - sites/westernsnowconference.org/PDFs/2004Teti.pdf ER - TY - Generic T1 - Effect of alternative silvicultural treatments on snow accumulation in lodgepole pine stands, Montana, U.S.A. T2 - 72nd Annual Western Snow Conference Y1 - 2004 A1 - Woods, S.W. A1 - McCaughey, W. A1 - Ahl, R. A1 - Sappington, J. KW - Forest thinning, snow accumulation, Tenderfoot Creek, SWE, interception AB - Alternative silvicultural treatments such as thinning can restore the productivity and diversity of forested watersheds and reduce wildfire hazards, but the hydrologic effects of these treatments are not well defined. We evaluated the effect of even thinning (SE) and group-retention thinning (SG), both with ~ 60 % basal area removal, on snow accumulation in lodgepole pine stands at the Tenderfoot Creek experimental forest, west-central Montana. In 2003 and 2004, the snow water equivalent (SWE) close to the seasonal peak was measured at >250 locations in the SE and SG treatments, and a control. In both years, the mean SWE in the SE treatment was significantly higher than in the control and the SG treatment (P<0.0001). In contrast, the mean SWE in the SG treatment was not significantly different from the control. Spatial variability of SWE was up to 3 times higher in the SG treatment than in the SE treatment or the control. The increased snow accumulation in SE treatments is attributed to reduced interception. In the SG treatment, losses due to wind scour and evaporation offset gains due to reduced interception. These results demonstrate that thinning can have substantially different effects on snow accumulation depending on the spatial arrangement of the treatments. JF - 72nd Annual Western Snow Conference T3 - Proceedings of the 72nd Annual Western Snow Conference PB - Western Snow Conference CY - Richmond, B.C. UR - sites/westernsnowconference.org/PDFs/2004Woods.pdf ER - TY - Generic T1 - Early forecasts of snowmelt runoff using SNOTEL data in the Upper Rio Grande Basin T2 - 71st Annual Western Snow Conference Y1 - 2003 A1 - DeWalle, D.R. A1 - Eismeier, J.A. A1 - Rango, A. KW - Runoff forecasting, SNOTEL, Rio Grande, early season forecasts AB - Forecasts using SNOTEL data on November 1 and December 1 gave the best estimates of spring snowmelt runoff volumes almost as frequently as forecasts on March 1 and April 1 for the Upper Rio Grande basin in Colorado during 1983-2001. Forecasts for 2002, a record drought year, greatly overestimated flow volumes regardless of prediction month. Attempts at improving predictions using the El Nino/La Nina Southern Oscillation Index were not successful. JF - 71st Annual Western Snow Conference T3 - Proceedings of the 71st Annual Western Snow Conference PB - Western Snow Conference CY - Scottsdale, Arizona UR - sites/westernsnowconference.org/PDFs/2003DeWalle.pdf ER - TY - Generic T1 - EFFECTS OF STORM TRAJECTORIES ON SNOWFALL CHEMISTRY IN ROCKY MOUNTAIN NATIONAL PARK, COLORADO T2 - 69th Annual Western Snow Conference Y1 - 2001 A1 - Ingersoll, G. P. A1 - Tonnessen, K. A. A1 - Campbell, D.H. A1 - Glass, B.R. A1 - Torizzo, A.O. KW - Simulation model, SNOTEL, Snow chemistry AB -

Snowfall samples from snowstorms lasting 1 to 4 days were collected near the Bear Lake snow telemetry (SnoTel) site in Rocky Mountain National Park, Colorado (ROMO), during the 1998-99 snowfall season to determine if storms moving in from different directions affect the chemistry of precipitation in the park. Storm pathways to Bear Lake during snowfall events were estimated using the HYSPLIT4 backward-trajectory model developed by the National Oceanic and Atmospheric Administration. Deposition of acidic ions of nitrate and sulfate in snowfall during the study varied substantially (two- to threefold) depending on storm trajectory because air masses traversing the park originated from different surrounding areas, including some having large sources of emissions of nitrate and sulfate. Concentrations of nitrate and sulfate in samples were lowest when storms reached ROMO from north and east of the park and were elevated when air masses traveled from the west where a number of power plants are located. Concentrations were highest in storms reaching ROMO from the south, a region with urban areas including Metropolitan Denver.

JF - 69th Annual Western Snow Conference T3 - Proceedings of the 69th Annual Western Snow Conference PB - Western Snow Conference CY - Sun Valley, Idaho UR - sites/westernsnowconference.org/PDFs/2001Ingersoll.pdf ER - TY - Generic T1 - THE EFFECT OF VARIABLE PATTERNS OF SNOW DEPOSITION AND DRIFTING ON SNOWMELT, RUNOFF, AND STREAM DISCHARGE IN A SEMI-ARID MOUNTAIN BASIN T2 - 69th Annual Western Snow Conference Y1 - 2001 A1 - Marks, D. A1 - Winstral, A. KW - Reynolds Creek, Snow covered area, Snow distribution AB - In semi-arid mountainous regions, local topography and canopy cover strongly affect wind patterns during storms which alters snow distribution and causes the development of hydrologically significant drifts. While large drifts may cover only 5—15% of the basin area, they can hold 50% or more of the basin SWE at peak accumulation and 75—100% of the basin SWE in late spring. Snowmelt from the drifts provides essentially the only source of water to the basin in late spring and early summer, and therefore directly affects basin ecology, runoff response, and the basin hydrograph. To understand how snow distribution and drifting affect the timing and magnitude of snowmelt and the delivery of melt- water to the stream, we simulate both the patterns of snow deposition and melt over a small headwater basin in the Owyhee Mts. (the Reynolds Mountain East basin (0.36 kin2)) using the energy balance snowmelt model ISNOBAL. Simulations were run for several snow seasons in the 1980’s for which time-series aerial photos monitoring of the location and depletion of snow drifts during melt-out were available. Precipitation input was modeled as a function of topographic exposure relative to storm-event winds and the difference in storm-event catch between a sheltered site and an exposed site. Snowcover in the modeled drift zones lasted well into the spring and showed good agreement with drift assessments made from time-series late-season aerial photography. This experiment shows that disparate patterns of snow deposition and melt, including the effect of drifting, which is typical of semi-arid mountain basins, can be modeled as a function of terrain and vegetation. JF - 69th Annual Western Snow Conference T3 - Proceedings of the 69th Annual Western Snow Conference PB - Western Snow Conference CY - Sun Valley, Idaho UR - sites/westernsnowconference.org/PDFs/2001Marks.pdf ER - TY - Generic T1 - An enhanced technique for a more reliable daily snow measurements with an antifreeze-based tipping bucket gauge T2 - 68th Annual Western Snow Conference Y1 - 2000 A1 - Carcoana, R. A1 - Enz, J.W. KW - Instrumentation, Precipitation gauge, Snow instrumentation, Snow measurement, Tipping bucket AB - The record snowfall during the 1996-1997 winter season and subsequent spring flood stressed the need for a suitable method to measure daily snowfall at all 52 North Dakota Agricultural Weather Network (NDAWN) stations. Our goal was to obtain accurate daily winter precipitation values from a remote automatic weather station. In November 1997, a system comprised of a Texas Electronics TE5253 rain gauge with a Campbell Scientific CS705 antifreeze based snow adapter, suitable for obtaining a reasonable estimate of the total seasonal precipitation (McCaughey and Fames, 1996), was installed at Fargo, North Dakota NDAWN station. Laboratory testing identified an antifreeze overflow restriction and a system support problem. We redesigned the shape of the overflow tube and added surfactant to the antifreeze mixture to diminish surface tension. We installed a weight support (tripod) and a side post to increase gauge stability in windy conditions and maintain a plumb position. The new system was tested during the second half of the 1997-98 winter, and the 1998-99 and 1999-2000 v.inter seasons. Comparative data for each snow precipitation event were recorded, collected and analyzed from three different sources: NWS Coop observer located about two miles E, a standard NWS universal Belfort weighing gauge, and the adjacent TE525/CS705 tipping bucket gauge/snow adapter at the Fargo, NDAWN station. The combination of the new overflow tube design, added surfactant and a reliable support system, enhanced the flow timing and provided more reliable daily totals. JF - 68th Annual Western Snow Conference T3 - Proceedings of the 68th Annual Western Snow Conference PB - Western Snow Conference CY - Port Angeles, Washington UR - sites/westernsnowconference.org/PDFs/2000Carcoana.pdf ER - TY - Generic T1 - Effects of inter-annual and decadal-scale climate variability on Winter and Spring streamflow in western Oregon and Washington T2 - 68th Annual Western Snow Conference Y1 - 2000 A1 - Koch, R.W. A1 - Fisher, A.R. KW - Climate change, SOI AB - River basins in western Oregon and Washington that have a seasonal snowpack exhibit a dual-peaked hydro graph. The early peak is due to the winter maximum rainfall occurring at lower elevations and the later one is due to snowmelt. Three such basins were examined to determine whether the distribution of streamflow within the year is related to indices of either inter-annual (as measured by the Southern Oscillation Index, SOl) or inter-decadal (as measured by the Pacific Decadal Oscillation, PDO) variability in the climate. The relationship of streatnflow to SOl is affected by the phase of the PDO. During below average phases of the PDO (generally warm SST's in the north Pacific Ocean, except along the North American coast). streamflow exhibits a significant relationship to SOl. where as during the above average phase. there is no statistically significant relationship between streamflow and SOl. Statistically significant differences in the distribution of flow within the year were also noted and were related to the phase of the PDO. JF - 68th Annual Western Snow Conference T3 - Proceedings of the 68th Annual Western Snow Conference PB - Western Snow Conference CY - Port Angeles, Washington UR - sites/westernsnowconference.org/PDFs/2000Koch.pdf ER - TY - Generic T1 - Estimating snowpacks in a dynamic prairie environment T2 - 68th Annual Western Snow Conference Y1 - 2000 A1 - Steppuhn, H. KW - Measurement techniques, Snow covered area, Snow measurements, Statistics AB - The Northern Great Plains and the Canadian Prairies cover a vast area east of the North American Rocky Mountains. The climates of these plains and prairies exemplify the classic mountain rain-shadows at mid-Iatitudes with two dominant seasons: winter, and summer. Snow can blanket these lands at any time from September through June. The snowfall can accumulate on the ground forming snowpacks which vary widely in magnitude, areal coverage, and persistence from location to location and from year to year.Widely varying snowpack depths (d), water equivalents (WE), and areal covers (A) typify cold, windy, prairie environments on the North American plains and prairies. The wide range in seasonal snowpack accumulations stems from the region's size and dynamic weather. Extremes are expected almost every year but typically occur in different locations. Although accurate estimates of snowpack d, WE, and A serve for effective resource management, they are often difficult to obtain. A technique, based on stratification according to terrain and vegetation, utilizes precipitation gauge accumulations to estimate mean snowcover WE-values as the season progresses. Gauge accumulations are adjusted for evaporation and meltwater releases by incorporating com mon meteorological station measurements. A model of the technique applied to data from Saskatchewan, improved R2 values from 0.40 to 0.76 for regressions of precipitation gauge WEs with areal mean WEs measured in field snow surveys. JF - 68th Annual Western Snow Conference T3 - Proceedings of the 68th Annual Western Snow Conference PB - Western Snow Conference CY - Port Angeles, Washington UR - sites/westernsnowconference.org/PDFs/2000Steppuhn.pdf ER - TY - Generic T1 - The effects of evapo-sublimation on the planning of precipitation and runoff augmentation programs T2 - 67th Annual Western Snow Conference Y1 - 1999 A1 - Dexter, L.R. A1 - Avery, C.C. A1 - Delinger, W. A1 - Sayers, R. KW - Forecasting, Snowpack, Snowpack augmentation, Sublimation AB - No abstract JF - 67th Annual Western Snow Conference T3 - Proceedings of the 67th Annual Western Snow Conference PB - Western Snow Conference CY - South Lake Tahoe, California UR - sites/westernsnowconference.org/PDFs/1999Dexter.pdf ER - TY - Generic T1 - Equivalent permeability of a continental, alpine snowpack T2 - 67th Annual Western Snow Conference Y1 - 1999 A1 - Fox, A.M. A1 - Williams, M.W. KW - Lysimeters, Meltwater flow, Snowpack permeability AB - Most snowpacks are not homogeneous, but consist of a number of snow and ice layers with varying permeabilities. In such cases, an 'equivalent' permeability can be used as an integrated or bulk property of the entire snowpack depth and is a useful parameter for gravity-flow and numerical models of meltwater flow through isothermal snowpacks. Calculated surface meltwater flux and Iysimeter discharge were used to establish daily relationships between specific meltwater fluxes and wavespeeds through the snowpack at a continental, alpine site in 1996 and 1997. These relationships were used to determine a pore-size distribution index (E) and to calculate equivalent permeability. Values for E were found to vary considerably and could not be related to other measured snowpack properties. Values were in the lower range of those previously reported, often less than 3, and were highly dependent on the range of meltwater fluxes used in calculations. Equivalent permeability was also at the lower limit of values reported in the literature, and varied by 2 orders of magnitude from 1.08 x 10 to the 11th to 2.79 x 10 to the 8th m2. In 1997 it declined considerably over 16 days. JF - 67th Annual Western Snow Conference T3 - Proceedings of the 67th Annual Western Snow Conference PB - Western Snow Conference CY - South Lake Tahoe, California UR - sites/westernsnowconference.org/PDFs/1999Fox.pdf ER - TY - Generic T1 - Effects of el niño and la niña events on precipitation, temperature, and natural runoff volumes in Alberta, Canada T2 - 66th Annual Western Snow Conference Y1 - 1998 A1 - Keller, R. KW - El niño, La niña, Precipitation, Runoff, Temperatures AB - Precipitation, temperature and natural runoff volumes over the province of Alberta, Canada were associated with the two extreme phases of Southern Oscillation, namely El Nino and La Nina. Spatial and temporal data were analyzed for the 1911-1995 period for the first winter following the onset of the El Nino and La Nina cycles in Alberta. The strongest signal for El Nino and La Nina appeared in the December to February period following their onset with some signal apparent in the November to March period. This paper includes a general description of the climate processes involved and the results for the December to February period following the onset of El Niño and La Nina events. The analyses include 22 El Nino and 14 La Nina events that occurred in the study period with an update on the current 1997-98 El Nino event. The results for the December to February (winter) period following the onset of El Nino show statistically significant above-average temperatures in all areas of Alberta. Decreased winter precipitation was evident at all stations following the onset of El Nino, however differences were very small at most locations. Natural runoff volume (computed for the February to July period) on average, provided below-average values following El Nino winters.Conversely, significant below-average temperatures were found in Alberta for the winter following the onset of a La Nina event. La Nina events provided significantly above-average precipitation at all sites and subsequently, above-average natural runoff volumes were found. JF - 66th Annual Western Snow Conference T3 - Proceedings of the 66th Annual Western Snow Conference PB - Western Snow Conference CY - Snowbird, Utah UR - sites/westernsnowconference.org/PDFs/1998Keller.pdf ER - TY - Generic T1 - El Niño/Southern oscillation signals in the long term climate of Donner Summit, California T2 - 66th Annual Western Snow Conference Y1 - 1998 A1 - Osterhuber, R.J. KW - El Niño, Ocean surface temperature, SOI AB -

The latest El Nino event has prompted questions about the predictability of North American weather based on therelative strength of the Southern Oscillation Index (SOl). The annual precipitation, snowfall, and air temperature data from an area near Donner Pass, California have been analyzed in comparison with the SOI from the equatorial Pacific Ocean. There was found to be a positive correlation between decreasing SOl values and increasing annual precipitation; a positive correlation between increasing SOl values and increasing annual snowfall; and a positive correlation between increasing SOl values and increasing average annual air temperature. All these correlations, however, are weak. 64 % of the wettest years on record occurred with alow SOl, and 52% of the driest years on record occurred with a high SOl. Data was available from 1900 through 1997 excluding 1907, 1908, 1914, 1915, and 1932.

JF - 66th Annual Western Snow Conference T3 - Proceedings of the 66th Annual Western Snow Conference PB - Western Snow Conference CY - Snowbird, Utah UR - sites/westernsnowconference.org/PDFs/1998OsterhuberA.pdf ER - TY - Generic T1 - Estimating spatial distribution of snow water equivalence in a montane watershed T2 - 65th Annual Western Snow Conference Y1 - 1997 A1 - Elder, K. A1 - Rosenthal, W. A1 - Davis, R.E. KW - Kings River, LandSat, Modeling AB - We describe an approach to model distributed snow water equivalence (SWE) that merges field measurements of depth and density with remotely sensed snow-covered area (SCA). In 1993 two teams conducted an intensive snow survey in the 92.8 km2 Blackcap Basin of the Kings River. We measured snow depth at 709 points and density in five snow pits and along five transects using a Federal Sampler. Sample locations were chosen to be representative of the range of elevations, slopes and aspects of the basin. Regression tree models showed that net radiation, elevation, and slope angle account for 60- 70% of the variance in the depth measurements. Density was distributed over the basin on a 30 m grid with a multiple linear regression model that explained 70% of the observed variance as a function of the same three variables. The gridded depth estimates combined with modeled density produced spatially distributed estimates of SWE. An unsupervised spectral unmixing algorithm estimated snow cover fractions from Landsat-5 Thematic Mapper data acquired at the time of the snow survey. This method provides a snow cover fraction estimate for every pixel. We used this subpixel map as our best estimate for SCA and combining it with the SWE map allowed us to compute SWE volume. We compared the estimated volume using the subpixel SCA map with several SCA maps produced with simulations of binary SCA mapping techniques. Thresholds of 40%, 50% and 60% fractional cover were used to map binary cases of full snow cover or no snow cover. The difference in basin SWE volume was up to 13% depending on the threshold used to classify snow-covered versus snow-free areas. The percent differences in volumes roughly couesponded to the percent differences in SCA between the methods. JF - 65th Annual Western Snow Conference T3 - Proceedings of the 65th Annual Western Snow Conference PB - Western Snow Conference CY - Banff, Alberta UR - sites/westernsnowconference.org/PDFs/1997Elder.pdf ER - TY - Generic T1 - The effects of light intensity and blu, green and red wavelengths on mating strategies in the snow alga, Chloromonas sp -d, from the Tughill Plateau, New York State T2 - 65th Annual Western Snow Conference Y1 - 1997 A1 - Hoham, R.D. A1 - Kang, J.Y. A1 - Hasselwander, A.J. A1 - Behrstock, A.F. A1 - Blackburn, I.R. A1 - Johnson, R.C. A1 - Shlag, E.M. KW - Chloromonas, Light intensity, Light wavelength, Mating AB - In this study, four strains of the snow alga, Chloromonas sp.-D, were isolated from the Tughill Plateau, Whetstone Gulf State Park, NY, to study mating strategies under different light conditions. Experiments were conducted in white acrylic test tube holders that were placed in growth chambers with controlled light, temperature and photoperiod. Two light sources were used, Wide-Spectrum (WS) and CooI-White (CW), and the effects of blue, green and red light were tested by covering the holders with corresponding cellophanes. Cells were fixed with OsO4 and observed and tabulated using Zeiss phase-contrast microscopes. Using similar light intensities, blue light regimes produced more matings than green light regimes in four of four trials (two were significantly different, P<0.05), and blue light regimes produced more matings than red light regimes in seven of eight trials (three were significantly different, P<0.05). There were no trends in mating when green and red light regimes were compared in three trials. A photon light intensity of 200 I'mol m-2 S-I produced the most mating under both WS and CW regimes, but more mating occurred under CW in all intensities tested. When red light regimes of higher photon intensity (180 I'mol m-2 S-I) were compared to those of blue light regimes of lower intensity (60 I'mol m.2 S-I), more mating occurred under red light in four of four trials, but none were significantly different. Mating pairs of three types were observed: oblong-oblong (o-o), oblong-sphere (o-s) and sphere-sphere (s-s). Cell packs that produced mating types and o-o mating pairs diminished with time. However, o-s and s-s mating pairs and quadriflagellate zygotes produced from the mating pairs increased with time. JF - 65th Annual Western Snow Conference T3 - Proceedings of the 65th Annual Western Snow Conference PB - Western Snow Conference CY - Banff, Alberta UR - sites/westernsnowconference.org/PDFs/1997Hoham.pdf ER - TY - Generic T1 - An experiment in use of seasonal long-range weather forecasts for water supply forecases in northern California T2 - 65th Annual Western Snow Conference Y1 - 1997 A1 - Roos, M. A1 - Ross, C. KW - Long range, Streamflow forecasts, Weather forecasts AB - From 1978 through 1992 Scripps Institution of Oceanography made quarterly long-range weather forecasts of precipitation in the Sierra Nevada. The 15 year experiment showed some skill in the winter and spring season. In the 1980s an attempt was made to apply the skills that existed to an early season December 1 forecast of water year runoff on selected rivers. The methodology of adjusting the conventional runoff forecast and the conventional expected range of runoff (which are based on climatology for future weather) for the demonstrated weather forecasting skill will be described in the paper. Some test results are shown. Unfortunately, the weather forecasting skills declined during the period of hydrological testing to below the threshold of usefulness and the forecasting experiment was put aside for a later time. But we believe there is merit to documenting the methodology and results of this experiment for other professionals. JF - 65th Annual Western Snow Conference T3 - Proceedings of the 65th Annual Western Snow Conference PB - Western Snow Conference CY - Banff, Alberta UR - sites/westernsnowconference.org/PDFs/1997Roos.pdf ER - TY - Generic T1 - Effects of climate change on water resources and runoff in an alpine basin T2 - 65th Annual Western Snow Conference Y1 - 1997 A1 - Seidel, K. A1 - Ehrler, C. A1 - Martinec, J. KW - Model, Precipitation change, Runoff regime, Satellite, Seasonal snowcover, SRM-ETH, Temperature change AB - The combined influence of increased temperatures and changed precipitation on the seasonal snow cover and runoff is evaluated for the upper Rhine basin at Felsberg (3250 km2, 560-3614 m a.s.l.). The runoff regime reflects the snow accumulation in the winter half year and snow-melt in the summer half year. The method of predicting future runoff regimes is based on high resolution periodical snow cover mapping by satellites in order to evaluate the climate-effected snow cover and runoff by the SRM-ETH model. Conditions of the present climate are represented by a nonnalised year. Snow conditions and yearly hydrographs are evaluated for the years 2030 and 2100 according to the given climate scenarios for this region. Quantitative results indicate the decrease of the snow accumulation on 1 April as well as the seasonal redistribution and changes of runoff. JF - 65th Annual Western Snow Conference T3 - Proceedings of the 65th Annual Western Snow Conference PB - Western Snow Conference CY - Banff, Alberta UR - sites/westernsnowconference.org/PDFs/1997Seidel.pdf ER - TY - Generic T1 - The effect of a canopy on the snowmelt energy balance T2 - 64th Annual Western Snow Conference Y1 - 1996 A1 - Adams, R.S. A1 - Spittlehouse, D.L. A1 - Winkler, R.D. KW - Clearcut, Eddy correlation, Energy balance, Engelmann Spruce, Lodgepole Pine KW - Subalpine fir AB - Energy balances over snow in a clearcut, an adjacent mature Engelmann spruce-subalpine fir forest, and a thinned and pruned juvenile lodgepole pine stand are presented. Net irradiance, soil heat flux density, and heat storage within the pack, were combined with eddy correlation measurements of sensible and latent heat flux density to estimate the energy available for snowmelt. When the ripe snow packs were melting, latent and soil heat flux density, and heat storage were negligible. A highly stable lower atmosphere resulted in low sensible heat flux densities. Although distinct differences in magnitude were observed between sites, net irradiance was the largest energy source for snowmelt at all three sites. Daily snowmelt calculated from energy balance measurements agreed well with measurements from snowmelt lysimeters. JF - 64th Annual Western Snow Conference T3 - Proceedings of the 64th Annual Western Snow Conference PB - Western Snow Conference CY - Bend, Oregon UR - sites/westernsnowconference.org/PDFs/1996Adams.pdf ER - TY - Generic T1 - The effect of ski run cutting and artificial showmaking on snow water accumulation at Big Sky Ski area, Montana T2 - 64th Annual Western Snow Conference Y1 - 1996 A1 - Birkland, K.W. KW - Artificial snow making, Montana, Ski runs AB - This study examines the effect of forest clearing for ski runs and artificial snowmaking on snow water accumulation at of Big Sky recreation area in southwest Montana. Extensive research shows that clearing the forest canopy for timber harvest increases water stored in the snowpack, but no studies have compared water stored in the compacted, skied, and machine groomed snowpack of ski runs with the water stored under the natural forest canopy. Thirty six sampling locations were selected, terrain variables (elevation, aspect and slope angle) were surveyed, and snow depth, density and water equivalence were measured both under the forest canopy and on the adjacent ski run. Additionally, some of the sampling locations were in areas with artificial snowmaking. Snowpack on the run has a higher density and water equivalence, and a similar depth, to snow off the ski runs. Elevation is the primary terrain variable that affects snowpack characteristics, and increases in snow water equivalence (SWE) with increasing elevation are similar to previously published research. There was no significant difference between snow water storage on ski runs with snowmaking and those without snowmaking, although the snow density on the runs with artificial snow was higher. Total increase in snowpack water storage for all ski runs at Big Sky was greater than 700,000 m3. This number is close enough to values derived from a model designed to measure water yield due to forest cutting that it appears that the clearing of ski runs causes similar increases in snowpack water storage and water yield as forest clearing for timber harvests. JF - 64th Annual Western Snow Conference T3 - Proceedings of the 64th Annual Western Snow Conference PB - Western Snow Conference CY - Bend, Oregon UR - sites/westernsnowconference.org/PDFs/1996Birkland.pdf ER - TY - Generic T1 - Early flood warning: Forecasting the Pacific Northwest T2 - 64th Annual Western Snow Conference Y1 - 1996 A1 - Pattee, S. A1 - Kammereck, A. KW - EFWS, HYDROMET, SNOTEL AB - The idea of being able to forecast the intensity of floods in the Pacific Northwest has been a dream for many years. Just thnk of the potential. Cities could be evacuated, property could be protected, livestock removed, roads blocke, sandbags placed, and most importantly -- lives saved.As like pioneers crossing the Cascade Mountains in the 1800's, Whatcom County has revolutionized the concept of early flooe warning for the Pacific Northwest. A concept that has been used in other locations such as California and British Columbia has been built unon and expanded into a complete system. JF - 64th Annual Western Snow Conference T3 - Proceedings of the 64th Annual Western Snow Conference PB - Western Snow Conference CY - Bend, Oregon UR - sites/westernsnowconference.org/PDFs/1996Pattee.pdf ER - TY - Generic T1 - Effects of microalgal blooms on Sierra Nevada snow albedo T2 - 64th Annual Western Snow Conference Y1 - 1996 A1 - Thomas, W.H. A1 - Duval, Brian KW - Albedo, Algae, Red snow AB - Initial (1993) investigations of snow albedo and snow color (caused by algae) in the Sierra Nevada of California showed that albedo was reduced in red snow patches as compared with that in white snow patches. In May-June, 1994, extensive concurrent measurements of snow albedo, snow algae numbers, and snow water content were made in the Tioga Pass area (upper Lee Vining Creek watershed) of the range. Statistically significant negative correlations were found between albedo and algal cell numbers and water content. However, red snow did not decrease mean albedos in large representative snowfields that contained algae. This was due to the patchiness of the algae, and mean albedos probably would not decrease because of algae over the whole Lee Vining Creek watershed. Thus water supply from melting snow would not be affected by the presence of algae. Especially in the early algal season, dirt, as well as algae, contributed to decreases in albedo. JF - 64th Annual Western Snow Conference T3 - Proceedings of the 64th Annual Western Snow Conference PB - Western Snow Conference CY - Bend, Oregon UR - sites/westernsnowconference.org/PDFs/1996Thomas.pdf ER - TY - Generic T1 - Evaluation of forest fire effects on snowpack accumulation and melt T2 - 63rd Annual Western Snow Conference Y1 - 1995 A1 - Dodd, B.N. A1 - Molnau, M. A1 - Robichaud, P. A1 - Belt, G. KW - Fire, Lysimeter, Rain-on-snow AB - In July of 1991 a fire swept through the Fourth of July Creek drainage in northwestern Montana. This area has a history of rain-on-snow events producing very high runoff and severely damaging streams. This study was set up to study the effects of fire severity on the delivery of snowmelt water to the soil.Snowmelt lysimeters were set up under four conditions a clearcut open site, a very heavily fire damaged site with a few snags left standing, an area of light burn damage and an undisturbed area that had not been logged since at least the 1920’s. Two lysimeters were installed in each treatment in the summer of 1993.Both snowmelt rates and volumes were compared for both snowmelt and rain-on-snow events. Usable data were collected in March and April.Overstory and basal area reduction due to fire or timber removal will increase mean air temperature while it decreases precipitation amount reaching the forest floor.Different meteorological events caused melt rates and volumes to be different for the different canopy overstory amounts. JF - 63rd Annual Western Snow Conference T3 - Proceedings of the 63rd Annual Western Snow Conference PB - Western Snow Conference CY - Sparks, Nevada UR - sites/westernsnowconference.org/PDFs/1995Dodd.pdf ER - TY - Generic T1 - Estimating monthly distribution of average annual precipitation in mountainout areas of Montana T2 - 63rd Annual Western Snow Conference Y1 - 1995 A1 - Farnes, P.E. KW - GIS, Lapse rate, Models, Precipitation distribution AB - Many computerized models and Geographic Information Systems (GIS) are being used to estimate average annual precipitation in mountains of the western United States. In most areas, there is a good correlation between average annual precipitation and elevation and most models use elevation to distribute annual precipitation to unmeasured areas. There is an increasing need to distribute these annual values to monthly averages. Some models use elevation to distribute monthly precipitation. Some models use the monthly distribution for long-term valley stations to distribute annual precipitation in higher elevations. Studies in Montana show there is a significantly different distribution of monthly precipitation between valley and mountain areas, particularly in the winter and spring months. Comparisons for some watersheds in Montana are shown and proposed procedure for distributing annual precipitation into realistic monthly increments is presented. JF - 63rd Annual Western Snow Conference T3 - Proceedings of the 63rd Annual Western Snow Conference PB - Western Snow Conference CY - Sparks, Nevada UR - sites/westernsnowconference.org/PDFs/1995Farnes.pdf ER - TY - Generic T1 - An evaluation of research programs at the Central Sierra Snow Laboratory, 1945-1964 T2 - 63rd Annual Western Snow Conference Y1 - 1995 A1 - Miller, D.H. KW - Evaluations, Research programs AB - Several public agencies took part in one or another of several cooperative programs investigating problems of the snow landscapes of the Sierra, and submitted their own problems of design and reservoir operation, river forecasting, and water and sediment yields. These problems were organized into a research program essentially centered on the fact that a snow landscape is the arena of interaction between water and energy; so the fluxes in these two physical budgets outlined our task. Of the three field basins active in the Cooperative Snow Investigations, the Central Sierra Snow Laboratory (CSSL) had the most detailed field observations; and in the later Snow Management program (FS), CSSL was the site of half of the research projects in the Sierra snow zone; it was the basin with which I grew most familiar.Field observations and data analyses emphasized heat supply, characteristics of the surface of the snow, water transmission through the deeper layers, and stream flow; techniques for hydrograph reconstitution for Castle Creek were validated in operational basins like the Yuba and Kootenai Rivers. In the second program at CSSL, detailed measurements of the forest environment of each snow course gave data for analyzing the separate effects of trees on shortwave radiation, longwave radiation, shelter, and wind transport.It is interesting that the intellectual curiosity of a university professor ninety years ago led to research that produced notable scientific findings about snow cover, and to physically sound operational techniques for design floods, flood forecasting, and managing the public domain. I feel privileged to have been a part of these major research programs in the physics of this complex mountain landscape, and now appreciate the invitation to evaluate these programs from the viewpoint of my subsequent scientific career. JF - 63rd Annual Western Snow Conference T3 - Proceedings of the 63rd Annual Western Snow Conference PB - Western Snow Conference CY - Sparks, Nevada UR - sites/westernsnowconference.org/PDFs/1995Miller.pdf ER - TY - Generic T1 - Estimating the mean squared prediction error of the areal snow water equivalent estimate for a river basin T2 - 62nd Annual Western Snow Conference Y1 - 1994 A1 - Carroll, S.S. A1 - Carroll, T.R. KW - Remote sensing, Simulated models, Statistical analysis AB - With the increased demand for water in the United States, particularly in the West, it is essential that water resources be accurately monitored. Consequently, the National Weather Service maintains a set of conceptual, continuous, hydrologic simulation models used to generate extended streamflow predictions, water supply outlooks, and flood forecasts. A vital component of the hydrologic simulation models is a snow accumulation and ablation model that uses observed temperature and precipitation data to simulate snow cover conditions. The simulated model states are updated throughout the snow season using snow water equivalent estimates obtained from airborne and ground-based snow water equivalent data. The National Weather Service has developed a spatial geostatistical model to estimate the areal snow water equivalent in a river basin. The estimates, which are obtained for various river basins in the West, are used to update the snow model. To facilitate updating of the simulated snow water equivalent estimates generated by the snow model, it is necessary to have estimates of the mean squared prediction errors of the areal snow water equivalent estimates. In this research, we derive an expression for the mean squared prediction error of the areal snow water equivalent estimate for a river basin. JF - 62nd Annual Western Snow Conference T3 - Proceedings of the 62nd Annual Western Snow Conference PB - Western Snow Conference CY - Sante Fe, New Mexico UR - sites/westernsnowconference.org/PDFs/1994Carroll.pdf ER - TY - Generic T1 - Estimating total snow volume in a small alpine watershed using remotely sensed data and ground-based surveys T2 - 61st Annual Western Snow Conference Y1 - 1993 A1 - Davis, R.E. A1 - Elder, K. A1 - Rosenthal, W. A1 - Melack, J. A1 - Sickman, J. KW - Remote sensing, Snow cover AB - Ground surveys of snow water equivalence and snow cover maps derived from Landsat TM imagery provided the basis for investigating different methods to estimate total snow volume in a small watershed of the eastern Sierra Nevada of California. Snow density profiles and Federal Snow Sampler observations along ground transects made up the measurements used to estimate the snow water equivalence at several points. The area of snow cover was estimated with two techniques, a supervised classification and a method based on spectral mixture modeling. Total snow volume was obtained by distributing snow water equivalence over the snow-covered area with the help of a digital elevation model. Snow volume estimates, in terms of their water equivalence, were compared with the estimated total snowmelt runoff. Total snowmelt runoff was estimated by subtracting baseflow determined with a graphical technique. The comparisons were evaluated in the context of potentially combining remote sensing data with traditional snow course measurements to determine total snow cover volume. JF - 61st Annual Western Snow Conference T3 - Proceedings of the 61st Annual Western Snow Conference PB - Western Snow Conference CY - Quebec City, Quebec UR - sites/westernsnowconference.org/PDFs/1993Davis.pdf ER - TY - Generic T1 - Estimating localized SWE on the Yellowstone northern range T2 - 61st Annual Western Snow Conference Y1 - 1993 A1 - Farnes, P.E. A1 - Romme, W.H. KW - Algorithm, SNOTEL, Snow cover AB - After the large fires of 1988 in Yellowstone National Park, many projects were initiated to study their effects. One of the studies involved the effects of fire on vegetation and ungulates on the northern winter range.Because snow water equivalent (SWE) is a significant factor in animal foraging and movement, it was necessary to develop a method that could use data from National Weather Service (NWS) climatological stations and Soil Conservation Service (SCS) snow courses and SNOTEL (SNOw Survey TELemetry) sites to predict SWE in areas of varying slopes, aspect, elevation, and forest cover. It was first necessary to estimate SWE at NWS climatic stations. The daily snow depth, precipitation and temperature values were used to estimate daily SWE. Daily SNOTEL SWE was used to estimate daily SWE at SCS snow courses. Algorithms were developed to estimate daily SWE for flat and open areas on the northern range not having significant drifting similar to data collection sites.A multidimensional nomograph was developed from measured data to estimate SWE for any slope and aspect within the northern range area. The habitat cover type was used to adjust SWE for forested areas.Techniques and relationships developed for the northern range would be transferable to other intermountain areas that accumulate a winter snowpack and that have daily climatic and/or snow pillow data. JF - 61st Annual Western Snow Conference T3 - Proceedings of the 61st Annual Western Snow Conference PB - Western Snow Conference CY - Quebec City, Quebec UR - sites/westernsnowconference.org/PDFs/1993Farnes.pdf ER - TY - Generic T1 - Examining the influence of snow cover on morning air temperature T2 - 61st Annual Western Snow Conference Y1 - 1993 A1 - Hogan, A. A1 - Ferrick, M. KW - Local influence, Temperature AB - There are large differences in mean minimum winter air temperature among very proximate New England stations. Daily differences are even greater when research sites are compared. We conducted a series of experiments, in morning twilight during the winter months, to examine the influence of topography and snow cover on early morning air temperature. We have proposed a hypothesis that the impoundment of the Connecticut River extending above the Wilder dam provides a temperature reference plane, allowing evaluation of physical factors modifying air temperatures adjacent to the reference plane. Analyses of surface air temperature with respect to elevation and distance along the Connecticut River valley show consistent vertical temperature structures that are related to snow cover. We present analyses of temperature structure and the relation of surface air temperature to vertical temperature structure in the vicinity of the reference plane. JF - 61st Annual Western Snow Conference T3 - Proceedings of the 61st Annual Western Snow Conference PB - Western Snow Conference CY - Quebec City, Quebec UR - sites/westernsnowconference.org/PDFs/1993Hogan.pdf ER - TY - Generic T1 - Expanding SCS's remote sensing program T2 - 60th Annual Western Snow Conference Y1 - 1992 A1 - Cooper, P.D. A1 - Werner, J.G. A1 - Schaeffer, G. KW - Climatic data, Global change, Meteor burst, Remote sensing, SNOTEL, Water quality AB - The Soil Conservation Service (SCS) is involved in an effort to expand it’s application of meteor burst communications from Western water supply forecasting into other resource management concerns. A pilot site was installed in Sherburne County, Minnesota, in May 1990. Local SCS offices have begun utilizing the site’s meteorological data for Evapotranspiration (ET) estimates. These ET estimates are made available to landowners for irrigation scheduling. The irrigation scheduling program is part of an SCS/Extension Service Water Quality Demonstration Project aimed at reducing nitrogen loading to groundwater in the Anoka Sand Plain area.Beginning August, 1991, the Minnesota site, along with ten other new installations east of the Rockies were equipped with meteorological and soil moisture and soil temperature sensors. This newest phase in SCS resource inventory operations is aimed at demonstrating the (etc.) JF - 60th Annual Western Snow Conference T3 - Proceedings of the 60th Annual Western Snow Conference PB - Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/1992Cooper.pdf ER - TY - Generic T1 - Environmental influences on snow algal microbes T2 - 60th Annual Western Snow Conference Y1 - 1992 A1 - Hoham, R.W. KW - Algae, Ecology, Microbes, Physiology, Snow microbes AB - Microbes called snow algae are worldwide in their distribution from alpine and polar environments. These microbes have been reported from 13 western states during the time of snowmelt. They occupy extreme conditions of cold temperature acidified snow, high irradiation levers and minimum nutrients for growth during snowmelt and summer drought after snowmelt. Snow algae color the snow green, orange or red, and environmental factors influence the distributions of individual spedies. A recent study of red snow from Wyoming and red and green snow from Antarctica shows differences in pigment ratios, fatty acid ratios and total nitroben content. In another study closely related snow algae from the White Mtns. Arizona and the Adirondacks,N.Y., appear to have lost their capacity to reproduce sexually, but several observations of abnormal sexual reproduction have been observed. These reproductive strategies may be important for the survival of snow algae in the natural environment. JF - 60th Annual Western Snow Conference T3 - Proceedings of the 60th Annual Western Snow Conference PB - Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/1992Hoham.pdf ER - TY - Generic T1 - Estimation of 30 year average annual precipitation for SNOTEL sites in Idaho T2 - 60th Annual Western Snow Conference Y1 - 1992 A1 - Morrisey, P.S. KW - 30 year average annual precipitation, Daily precipitation, SNOTEL sites AB - The Soil Conservation Service (SCS) operates and maintains a network of 69 automated SNOTEL (SNOw TELemetry) sites in Idaho. Most have a continuous daily precipitation data record from 1982. 1961-1990 average annual precipitation (AAP) was estimated for 65 of the sites having more than five years of data using simple linear regression. Water year annual precipitation for the available years was compared to nearby national Weather Service (NWS) stations. Up to 14 NWS stations were analyzed for each SNOTEL site. The three highest correlating NWS sites for each SNOTEL site were selected and the 1961-1990 AAP at the NWS sites was used to estimate three 30 year AAP values for each SNOTEL site from the regression equations. The final 1961-1990 AAP for the SNOTEL sites was the mean calculated from the three individual values. High correlations were consistently obtained between SNOTEL and NWS annual precipitation. JF - 60th Annual Western Snow Conference T3 - Proceedings of the 60th Annual Western Snow Conference PB - Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/1992Morrisey.pdf ER - TY - Generic T1 - Effects of sampling density on estimations of snowpack characteristics T2 - 59th Annual Western Snow Conference Y1 - 1991 A1 - Cooley, K.R. A1 - Rango, A. KW - Aerial photographs, Distribution, Sampling, Snow, Snowmelt, Variability AB - While remote sensing offers great potential for snowmelt modeling, many of the techniques being proposed need to be tested against ground truth (actual snow measurements), but how does one determine the number of measurements required? Unfortunately, the number may depend on the parameter being measured and on the variability of the snowpack. One of the problems in determining the density or intensity of measurements needed is the lack of validating information. In this study, samples obtained on a 30 by 30 meter grid over a 26 hectare wind swept basin in southwestern Idaho are used to determine the number of samples needed to adequately describe snowpack characteristics under conditions of extreme spatial and temporal variability. Estimates of snow covered area obtained from sample measurements are compared with estimates based on aerial photos. Estimates of snow water equivalent and snow depth are determined for a range of grid and sample spacings. JF - 59th Annual Western Snow Conference T3 - Proceedings of the 59th Annual Western Snow Conference PB - Western Snow Conference CY - Juneau, Alaska UR - sites/westernsnowconference.org/PDFs/1991Cooley.pdf ER - TY - Generic T1 - Effect of global warming on Sierra Nevada mountain snow storage T2 - 59th Annual Western Snow Conference Y1 - 1991 A1 - Tsuang, B.J. A1 - Dracup, J.A. KW - Global change, Global warming, Sierra Nevada AB - Snowmelt runoff processes in an alpine watershed located in the Sequoia National Forest are analyzed using an energy-based snowmelt runoff model. Using a global warming scenario, the results of the analysis indicate that the hydrograph of snowmelt runoff shifts between 19 and 93 days earlier and the snow season ends between 25 and 68 days earlier at an elevation of 2800 m. The most striking change is a decrease in the snow/precipitation ratio at elevations below 2300 m. Here the ecological balance suffers a major impact due to a small increase in air temperature that causes a significant amount of snow to occur as rain. In addition, the shorter snow season decreases the albedo of the land surface since the albedo of snow is much higher than that of vegetation or soil. As a consequence, regional warming is increased due to a snow albedo feedback process. JF - 59th Annual Western Snow Conference T3 - Proceedings of the 59th Annual Western Snow Conference PB - Western Snow Conference CY - Juneau, Alaska UR - sites/westernsnowconference.org/PDFs/1991Tsuang.pdf ER - TY - Generic T1 - An evaluation of methods used by different river forecast centers to calculate reasonable maximum and reasonable minumum forecasts T2 - 58th Annual Western Snow Conference Y1 - 1990 A1 - Huber, A.L. KW - Multiple regression, Reasonable maximum, Reasonable minimum, Statistics, Water supply forecasting AB - This paper compares methods used by the different river forecast centers for calculating the reasonable maximum and reasonable minimum water supply forecasts. Five procedures used by different forecast centers were identified and evaluated. Results from using the five methods on common watersheds with the same prediction equations are summarized and compared for four forecast dates. Although each method purports to provide estimates of the reasonable maximum and reasonable minimum that would be exceeded only 10 percent of the time, or once every ten years, the actual return periods for the difference methods ranged from 3 years to over 500 years. JF - 58th Annual Western Snow Conference T3 - Proceedings of the 58th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California UR - sites/westernsnowconference.org/PDFs/1990Huber.pdf ER - TY - Generic T1 - Estimating snow transport from wind speed records: estimates versus measurements at Prudhoe Bay, Alaska T2 - 58th Annual Western Snow Conference Y1 - 1990 A1 - Tabler, R.D. A1 - Benson, C.S. A1 - Santana, B.W. A1 - Ganguly, P. KW - Blowing snow, Snow fences, Snow transport, Snowdrifts, Wind speed AB - A process-based model for wind-transported snow developed by Pomeroy (1988) has been used to derive an equation relating total snow transport in the first 5 m above the surface, q(sub0-5) (kg/m.s), to 10-m wind speed, u(sub10) m/s:q(sub0-5)=u(sub10)exp4.04/458800This equation is valid for u(sub10) >or= 6.5 m/s when snow supply is unlimited. A four-year comparison at Prudhoe Bay showed that snow transport estimated by this relationship compared favorably with measured snow accumulation at tall snow fences when basic requirements for snow conditions and wind data were satisfied. Analysis of historical wind records at Prudhoe Bay for 1968-1989 provided estimates for snow transport. JF - 58th Annual Western Snow Conference T3 - Proceedings of the 58th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California UR - sites/westernsnowconference.org/PDFs/1990Tabler.pdf ER - TY - Generic T1 - Estimating the effects of wildfires on water supply in the northern Rocky Mountains T2 - 57th Annual Western Snow Conference Y1 - 1989 A1 - Farnes, P.E. A1 - Hartman, R.K. KW - Water supply forecasting, Wildfire AB - Wildfires during the summer of 1988 burned a significant portion of several Northern Rocky Mountain wastersheds. A procedure was needed to adjust pre-burn calibrated water supply forecasting procedures to reflect post-burn conditions. The described procedure operates with a set of physically based, empirical relationships derived from data collected in Western Montana and Northwestern Wyoming. The premise of the procedure is that a reduction in timber canopy will lead to reduced interception of snowfall and spring precipitation. It is proposed that reduce summer evapotranspiration will have a minor effect on the concurrent seasonal volume. Instead, reduced summer evapotranspiration will have its greatest effect on the following season's volume by providing a higher level of antecedent soil moisture. JF - 57th Annual Western Snow Conference T3 - Proceedings of the 57th Annual Western Snow Conference PB - Western Snow Conference CY - Fort Collins, Colorado UR - sites/westernsnowconference.org/PDFs/1989Farnes.pdf ER - TY - Generic T1 - Evolution of a research-oriented snowmelt-runoff simulation model into an operational forecasting tool T2 - 57th Annual Western Snow Conference Y1 - 1989 A1 - Rango, A. KW - Model development, Remote sensing, Snow cover, User compatibility AB - Although many snowmelt-runoff models are proposed, only a few make it to the stage of true operational application in the forecast mode.There are many pitfalls and barriers that must be overcome to successfully transform a research model into an operational product. Such evolution is a gradual process with many aspects to consider. Some important considerations are model complexity, user compatible software, operational requirements, availablitity of required input data, forcasts of meteorological data, simulation and forecast reliability, applicability in geographically diverse areas, and realtime updating capabilities. Experiences with the snowmelt-runoff model (SRM), which requires remote-sensing inputs, are used as examples of the evolutionary process. The current status on SRM will be examined, and specific forecasting situations will be illustrated on the Upper Rio Grande basin of Colorado. JF - 57th Annual Western Snow Conference T3 - Proceedings of the 57th Annual Western Snow Conference PB - Western Snow Conference CY - Fort Collins, Colorado UR - sites/westernsnowconference.org/PDFs/1989Rango.pdf ER - TY - Generic T1 - Evaporation and seepage from a livestock reservoir equipped with a snow fence for water recharge T2 - 57th Annual Western Snow Conference Y1 - 1989 A1 - Sturges, D.L. KW - Blowing snow, Livestock reservoirs, Snow drift, Snow fences AB -

Drifting snow can provide water to recharge livestock reservoirs on windswept lands that normally receive little surface inflow. Field experience with such installations indicates that snow fences collect significant quantities of snow, but that the stored water is often gone by the grazing season. A study was conducted in the spring of 1988 to determine the quantity of water lost by evaporation and by seepage from a small livestock reservoir recharged from snow deposited by a snow fence. Measurements started during snowmelt and extended through June when the pond was nearly dry. Evaporation was sensitive to daily wind movement and ranged to 1.3 cm per day. Pond seepage, however, exceeded evaporation several fold. The factor limiting success of the snow management effort was leakage from the reservoir.

JF - 57th Annual Western Snow Conference T3 - Proceedings of the 57th Annual Western Snow Conference PB - Western Snow Conference CY - Fort Collins, Colorado UR - sites/westernsnowconference.org/PDFs/1989SturgesB.pdf ER - TY - Generic T1 - The effect of in situ evaporation on perceived snow distribution in partially clear-cut forests T2 - 56th Annual Western Snow Conference Y1 - 1988 A1 - Swanson, R.H. KW - Clear-cutting effects, Evaporation from snow, Snow measurements AB - Differences in snow found under trees and within clearings of partially clear-cut forests are variously attributed to interception, redistribution and/or aerodynamic trapping of the falling snow. Measurements in Alberta during 1973 revealed that the snow present on the tree- or clearing-side of the sunlit edges of 60 to 120 m diameter circular clearings was less than at the shaded edge, raising a fourth possibility; that of differential evaporation or melting of snow between the sunlit and shaded portions of clearings. The evaporation from snow during precipitation-free days in January through March 1985 was 0.18 mm d-1 under the trees on the shaded edge; 0.42 mm d-1 under trees on the sunlit edge. The 4 to 7 mm of evaporation estimated during the 22 snow-free days in February 1973, was less than 1/3 the 25 mm of precipitation that occurred. On March 1, the snow measured on treed and open sides of the north edge was less than the amount measured there on February 1. More than 18 mm of snow loss were unaccounted for by in situ evaporation from the snowpack. JF - 56th Annual Western Snow Conference T3 - Proceedings of the 56th Annual Western Snow Conference PB - Western Snow Conference CY - Kalispell, Montana UR - sites/westernsnowconference.org/PDFs/1988Swanson.pdf ER - TY - Generic T1 - Estimating dates of the snow accumulation season T2 - 56th Annual Western Snow Conference Y1 - 1988 A1 - Tabler, R.D. KW - Air temperatures, Precipitation, Snow accumulation, Snow transport AB - It is often necessary to estimate the average snow accumulation season, defined as extending from the first persistent snowfall to the time of peak water-equivalent, as a first step in estimating average winter precipitation. The snow accumulation season is shown to be delimited by dates when air temperatures reach 0 degrees C, as computed from mean monthly temperatures. For locations lacking climatological records, estimates can be derived from multiple regressions relating 0 degrees C dates at surrounding stations to elevation, latitude, and longitude. Regression equations are presented for all states in the snow belt, and a general equation indicates that dates of the snow accumulation season vary at the average rate of 2.5 days per 100 meters of altitude, 5.5 days per degree of latitude, and 1 day per degree of longitude, earlier northward, eastward, and upward in the fall, and the reverse in the spring. JF - 56th Annual Western Snow Conference T3 - Proceedings of the 56th Annual Western Snow Conference PB - Western Snow Conference CY - Kalispell, Montana UR - sites/westernsnowconference.org/PDFs/1988Tabler.pdf ER - TY - Generic T1 - Evaluation of the NWSRFs model on a montana watershed T2 - 54th Annual Western Snow Conference Y1 - 1986 A1 - Cooley, K.R. KW - NWSRFS, Runoff Modeling, Snowmelt Runoff AB - In an effort to improve, 1) snow accumulation and melt routines in watershed hydrology models, and 2) water supply forecasting techniques; components of the NWSRFS Model were evaluated using data from a Montana watershed. Specifically, the snow sub-model HYDRO-17 was tested against data from two snow pillow sites, and additional sub-models relating to soil moisture, unit hydrographs, and stresamflow routing were tested against streamflow from the Lower Willow Creek Basin in southwestern Montana. Relationships between snow pillow site and zonal snow water equivalent are presented. Also presented are methods used to arrive at preliminary estimates of some model parameters, assumptions used to develop needed snow pack volume, and variability of parameters with time and area of consideration. Results emphasize the importance of on-site data, and the expedience of properly locating precipitation and snow water equivalent monitoring equipment. JF - 54th Annual Western Snow Conference T3 - Proceedings of the 54th Annual Western Snow Conference PB - Western Snow Conference CY - Phoenix, Arizona UR - sites/westernsnowconference.org/PDFs/1986Cooley.pdf ER - TY - Generic T1 - Estimating snow course water equivalent from SNOTEL pillow telemetry: an analysis of accuracy T2 - 54th Annual Western Snow Conference Y1 - 1986 A1 - Palmer, P.L. KW - Estimating snow course data, SNOTEL, Snow course, Snow pillow AB - Regression analysis between SCS SNOTEL snow pillow and manually measured snow course data allows estimates of snow course water equivalent to be made directly from pillow telemetry. The regression equations were based on data collected over a five year period at 62 snow data collection sites in Idaho.Actual snow course measurements taken during the 1985 snow season were compared to estimates made from snow pillow telemetry. The residuals were divided into accumulation season and melt season categories. In both cases, errors were normally distributed around the mean. Accumulation season estimates had an average absolute error of 5.6 percent and a standard deviation of 9.5 percent. During the melt season, errors were higher and more widely distributed, with an average absolute error 11.8 pecent and standard deviation of 21.4 percent. This analysis provides the necessary relationship to update streamflow forecasts at any time of the month using real-time telemetered data. Examination of estimating error provides a basis for sensitivity analysis of forecasts based on telemetered data. JF - 54th Annual Western Snow Conference T3 - Proceedings of the 54th Annual Western Snow Conference PB - Western Snow Conference CY - Phoenix, Arizona UR - sites/westernsnowconference.org/PDFs/1986Palmer.pdf ER - TY - Generic T1 - The effect of patch clearcutting on the water balance of a subalpine forest slope T2 - 54th Annual Western Snow Conference Y1 - 1986 A1 - Troendle, C.A. A1 - Meiman, J.R. KW - Clearcutting effects, Soil water recharge, Subalpine forest AB - Peak water equivalent in the snowpack, soil moisture content before, during, and after snowmelt, and soil moisture content during the growing season were monitored on three adjacent study plots on a 35 percent north-facing slope. After 2 years of calibration, the center plot was clearcut, creating a 4-tree height opening in the 20-m stand. During the next 3 years, up to 50 percent more snow water equivalent accumulated in the opening than in the upwind control. This increase is evident both for individual events and for the entire season. The increases occurred primarily during the snowfall events, where no measurable redistribution occurred between events. Soil water recharge in all plots was not affected by clearcutting. However, significantly less soil water depleted (-5.1 cm) from the clearcut plot than from either the up or downwind forest after harvest. Increased snowpack accumulation in the opening accounted for 14.8 cm of the estimated 19.9 cm increase in water available for streamflow for the clearcut; reduced soil water depletion accounted for the remaining 5.1 cm. JF - 54th Annual Western Snow Conference T3 - Proceedings of the 54th Annual Western Snow Conference PB - Western Snow Conference CY - Phoenix, Arizona UR - sites/westernsnowconference.org/PDFs/1986Troendle.pdf ER - TY - Generic T1 - Evaluation of the isotopic snow measurement gage T2 - 52nd Annual Western Snow Conference Y1 - 1984 A1 - Wheeler, P.A. A1 - Huffman, D.J. KW - Isotopic gage, Snow measurement AB - Isotopic snow measurement gages have been in use in the Western states for monitoring snow water equivalent for the last nine years. They have demonstrated several advantages over mechanical snow gages, but have also presented some problems. This paper will review the status of the Isotopic Gage in monitoring snow. It will briefly describe the principles by which it works, evaluate its past experience, discuss its advantages and problems, present current technologic advances by use with micro processors, and suggest future research which will improve reliability. One area of research discussed is the use of solid state detectors, such as cadmium telluride, to eliminate the need for high voltage circuits. JF - 52nd Annual Western Snow Conference T3 - Proceedings of the 52nd Annual Western Snow Conference PB - Western Snow Conference CY - Sun Valley, Idaho UR - sites/westernsnowconference.org/PDFs/1984Wheeler.pdf ER - TY - Generic T1 - Error assessment of airborne snow water equivalent measurements T2 - 50th Annual Western Snow Conference Y1 - 1982 A1 - Carroll, T.R. A1 - Jones, W.K. KW - Airborne snow water equivalent, Airborne soil moisture, Gamma radiation, Nuclear techniques AB - The National Weather Service maintains an operational Airborne Gamma Radiation Snow Survey Program in the upper Midwest. A network of 300 flight lines, each approximately 15 to 20 km long and 300 m wide, has been established in the region. Natural terrestrial gamma radiation data are collected over the flight lines by a low-flying aircraft and used to infer mean areal snow water equivalent and soil moisture values over the 4.5 to 6.0 km sq area. Errors in the airborne snow water equivalent and soil moisture measurements are due primarily to: (1) uncertainties in the ground soil moisture calibration, (2) errors in the instrumentation used to measure air mass, and (3) limited radiation counting statistics. Nonetheless, the airborne gamma radiation attenuation technique is capable of making a snow water equivalent with an error of less than 1.0 cm and a soil moisture measurement with an error of approximately 3.9 percent soil moisture. Sources of error are discussed using ground and airborne data collected during the 1982 snow season. JF - 50th Annual Western Snow Conference T3 - Proceedings of the 50th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1982Carroll.pdf ER - TY - Generic T1 - Eastern snowpack conditions - characteristics and significance T2 - 50th Annual Western Snow Conference Y1 - 1982 A1 - Eschner, A.R. KW - Eastern U.S., Runoff, Snow accumulation, Snowpack AB - Eastern snowpack conditions are sharply different from those in the west; but not necessarily in the ways we might imagine. In New York, the seasonal snowfall approaches the average seasonal snowfall in many western areas, and is well correlated with melt season streamflow volumes. In spite of a substantial annual precipitation uniformly delivered over the year, the seasons when snow is present on the ground or in the process of melting provide the bulk of streamflow for many areas in the East. Although approximately as much precipitation falls in the growing season as the dormant season, its contribution to streamflow is small, and the snowpack is a significant parameter for predicting even total annual runoff. JF - 50th Annual Western Snow Conference T3 - Proceedings of the 50th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1982Eschner.pdf ER - TY - Generic T1 - Event reporting on Mount Saint Helens SNOTEL, flexibility for the future T2 - 50th Annual Western Snow Conference Y1 - 1982 A1 - Marron, J.K. A1 - Davis, R.T. KW - Automated, Event, Probe, Remote site, SNOTEL, Subsystem AB - The eruption of Mount Saint Helens on May 18, 1980 demonstrated the need for an event identification system to monitor changes in the snowpack caused by either meteorological or volcanic contributions. An event system was developed and installed on Mount Saint Helens that demonstrated both the flexibility and expandability of the Soil Conservation Services' Snow Telemetry System (SNOTEL). With minor modifications, as demonstrated by the Mount Saint Helens event system, there is a potential for an addition to the SNOTEL system. The flexibility of the system shows different data needs can be solved by use of the SNOTEL system. JF - 50th Annual Western Snow Conference T3 - Proceedings of the 50th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1982Marron.pdf ER - TY - Generic T1 - The effects of small clearcuts on water yield from the Deadhorse watershed; Fraser, Colorado T2 - 50th Annual Western Snow Conference Y1 - 1982 A1 - Troendle, C.A. KW - Clearcuts, Peak flows, Snowmelt, Vegetation manipulation, Water yield AB - Thirty-six percent of a small, 41-ha, subalpine watershed on the Fraser Experimental Forest was harvested using a system of small 5-Ha circular clearcuts. Annual water yield has increassed an average of 4.6 cm during the first 4 years after treatment with no detectable effect on peak flow rates. Significantly more snow was found in the openings than in the forest, but mean peak water equivalent for the watershed was not significantly altered. JF - 50th Annual Western Snow Conference T3 - Proceedings of the 50th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1982Troendle.pdf ER - TY - Generic T1 - Effects of snowdrift management on rangeland runoff T2 - 49th Annual Western Snow Conference Y1 - 1981 A1 - Cooley, K.R. A1 - Huber, A.L. A1 - Robertson, D.C. A1 - Zuzel, J.F. KW - Runoff, Snow fence, Snowdrift, Water supply AB - The installation of snow fences for increasing the size of snowdrifts, and thus increasing available water supplies, was investigated. Analysis of runoff from a 0.51 sq km watershed, and the size and shape of a drift induced by intallation of a 100 m long, 3 m high snow fence indicated that changes in runoff and size were insignificant, but the snow was distributed differently within the drift, possibly delaying snowmelt. Other studies have indicated increases, no change, and decreases in these parameters. Therefore, although increased drifts could provide important additions to local water supplies, it is very important to consider local conditions, which influence success before making any such installations. A more practical and reliable approach would be to locate natural drift sites and to install water harvesting systems in these areas. JF - 49th Annual Western Snow Conference T3 - Proceedings of the 49th Annual Western Snow Conference PB - Western Snow Conference CY - St. George, Utah UR - sites/westernsnowconference.org/PDFs/1981Cooley.pdf ER - TY - Generic T1 - Evaluation of SNOTEL data during January 9-16, 1980 storm in the Tahoe-Truckee basins T2 - 49th Annual Western Snow Conference Y1 - 1981 A1 - Moreland, R.E. KW - Precipitation data, Rain on snow event, SNOTEL data site, Snow pillow data, Snowpack profiles chart, Temperature data AB - This paper covers the operation of SNOTEL data sites during the severe storm period January 9 to 16, 1980, in the Tahoe-Truckee Basins of California and Nevada. These sites are part of the Soil Conservation Service's SNOTEL data collection system. Precipitation over the basins was almost continuous from the 9th through the 16th of January. The nine SNOTEL sites in the Tahoe-Truckee Basins and four sites in the adjacent Carson-Walker Basins were the only near real time data collection sites functioning in these basins during the January 9-16 event. Four SNOTEL sites--Ward Creek No. 3, Independence Lake, Fallen Leaf, and Marlette Lake--all with different average annual precipitation patterns, provided snowpack snow water, precipitation, and temperature information to help interpret what was happening during the entire January 9-16 event. Snow water equivalents and precipitation amounts of the Central Sierra Snow Lab and the Blue Canyon gage are also presented. Data collected at SNOTEL sites during this storm period appears to be quite accurate. JF - 49th Annual Western Snow Conference T3 - Proceedings of the 49th Annual Western Snow Conference PB - Western Snow Conference CY - St. George, Utah UR - sites/westernsnowconference.org/PDFs/1981Moreland.pdf ER - TY - Generic T1 - Evaluation of streamflow forecasting methods T2 - 47th Annual Western Snow Conference Y1 - 1979 A1 - Lettenmaier, D.P. A1 - Garen, D.C. KW - Comparative forecasting methods, Digital models, Water supply forecasting AB - Choice of a seasonal snowmelt runoff forecast model represents a tradeoff between data availability and the level of model complexity which can be justified. The basin storage accounting method, based on a storage estimate derived as the difference between accumulated low altitude precipitation and winter season runoff, with a correction for snow water equivalent observations represents a fairly accurate, although simple approach to forecasting seasonal runoff. The worth of precipitation and snow course data during the winter snow accumulation season, and the worth of forecasts of runoff forecast period precipitation may be evaluated in a relatively straightforward manner for such models. The evaluation is made directly through comparison of split sample seasonal forecast accuracy as a function of the number of precipitation stations and snow courses used. Precipitation forecast accuracy worth is assessed through comparison of split sample runoff forecast errors using long term average precipitation and recorded precipitation in the runoff forecast season, representing the range from no precipitation forecast to perfect precipitation forecast accuracy. JF - 47th Annual Western Snow Conference T3 - Proceedings of the 47th Annual Western Snow Conference PB - Western Snow Conference CY - Sparks, Nevada UR - sites/westernsnowconference.org/PDFs/1979Lettenmaier.pdf ER - TY - Generic T1 - Extended streamflow prediction during the California drought T2 - 46th Annual Western Snow Conference Y1 - 1978 A1 - Twedt, T.M. A1 - Burnash, R.J.C. A1 - Ferral, R.L. KW - Long range forecasting, Water supply forecasting AB - The California drought, which entered its second season during water year 1977, afforded an excellent opportunity to test and evalutate the Sacramento River Forecast Center (RFC) version of Extended Streamflow Prediction (ESP) during extreme hydrologic conditions. Because of the severity of the drought and its possible consequences, a wide variety of water users and managers had high interest in reliable long-range predictions during the year. The Sacramento RFC utilized a combination of a traditional regression-type water supply forecast approach, the more recently developed ESP model, and the rational analysis of hydrologic records from previous drought periods to produce such predictions. This paper presents a brief description of the development and operation of the Sacramento ESP model and discusses the resultant forecasts from these combined approaches. JF - 46th Annual Western Snow Conference T3 - Proceedings of the 46th Annual Western Snow Conference PB - Western Snow Conference CY - Otter Rock, Oregon UR - sites/westernsnowconference.org/PDFs/1978Twedt.pdf ER - TY - Generic T1 - An estimate of watershed efficiency for a Colorado alpine basin T2 - 44th Annual Western Snow Conference Y1 - 1976 A1 - Carroll, T. KW - Ablation of snowpack, Water supply forecasting, Watershed basin analysis AB - A two year project was conducted during 1973 and 1974 in a 3 sq km alpine basin located tweny miles west of Boulder in the city's watershed. The spring snow survey taken at peak accumulation indicated that 67 cm of snow water equivalent was held on the basin. subsequent ablation measurements revealed that slopes with a southern aspect contributed most per unit area to stream discharge. Stream stage was recorded at two locations within the basin from May until the end of september. Annual discharge from the basin was estimated to be 2.15 * 10(6)m(3), enough to fulfull the treated water requirement of boulder City for approximately two months. A water budget for the basin was established in terms of generated discharge, precipitation, and evapotranspiration. From the water budget, watershed efficiency (output expressed as a percentage of input) was estimated to be in excess of 90%. This estimage is in agreement with that other workers have found for watershed efficiencies in the Rocky Mountain alpine zone. Partially as a result of the high watershed efficiencies found in alpine areas, it has been suggested that these areas might be used to increase water supply to populated areas of the Western United States. JF - 44th Annual Western Snow Conference T3 - Proceedings of the 44th Annual Western Snow Conference PB - Western Snow Conference CY - Calgary, Alberta UR - sites/westernsnowconference.org/PDFs/1976Carroll.pdf ER - TY - Generic T1 - Evaporation losses of windblown snow, and the potential for recovery T2 - 41st Annual Western Snow Conference Y1 - 1973 A1 - Tabler, R.D. KW - Snow fence, Snow transport distance, Sublimation AB - Paper demonstrates potential of snow fences to increase storage on wind swept areas. Rm (Transport distance) is defined and used in various snow storage formulas. Rm was found to be about 4000 feet at sites between 7000 and 8000 feet in elevation before the wind completely sublimates the snowflake. JF - 41st Annual Western Snow Conference T3 - Proceedings of the 41st Annual Western Snow Conference PB - Western Snow Conference CY - Grand Junction, Colorado UR - sites/westernsnowconference.org/PDFs/1973Tabler.pdf ER - TY - Generic T1 - Environment and the snow resource T2 - 40th Annual Western Snow Conference Y1 - 1972 A1 - Kahan, A.M. KW - Environment, Snow cover accumulation AB - The concern about the environment in the snow resource is changing with the spirit of the times. This is the keynote of the seminar on ‘Environment and the Snow Resource’. JF - 40th Annual Western Snow Conference T3 - Proceedings of the 40th Annual Western Snow Conference PB - Western Snow Conference CY - Phoenix, Arizona UR - sites/westernsnowconference.org/PDFs/1972Kahan.pdf ER - TY - Generic T1 - Efficiency of foliage in horizontal interception T2 - 39th Annual Western Snow Conference Y1 - 1971 A1 - Fowler, W.B. A1 - Berndt, H.W. KW - Condensation, Hoar frost, Rime ice AB - Comparing deposition of rime and condensation growth of hoarfrost on a number of simple geometric solids and complex foliar elements indicates major differences occur in these processes with time. Differences in the rate of rime accumulations are a reflection of the changing effective surface accompanying simplification of form and enlargement of receptor elements. Heat loss through forced convection appears to be a major factor in condensation growth of hoarfrost. JF - 39th Annual Western Snow Conference T3 - Proceedings of the 39th Annual Western Snow Conference PB - Western Snow Conference CY - Billings, Montana UR - sites/westernsnowconference.org/PDFs/1971Fowler.pdf ER - TY - Generic T1 - The effect of the wilderness law on the collection of hydrologic data T2 - 36th Annual Western Snow Conference Y1 - 1968 A1 - Van de Erve, J. KW - Hydrologic data, Wilderness areas AB - A discussion of the effects of the new ‘Wilderness Law’ passed by Congress in 1964 is presented. This law has such drastic restrictions written into the text that programs designated to protect the area; water management, wildlife management, fire protection, pest control; are not allowed to enter the areas to carry out necessary work. Evidence of these restrictions are presented in documentary briefs submitted with this paper. References are made to 18 specific incidences of hindrance and are presented with data in tabular form. JF - 36th Annual Western Snow Conference T3 - Proceedings of the 36th Annual Western Snow Conference PB - Western Snow Conference CY - Lake Tahoe, Nevada UR - sites/westernsnowconference.org/PDFs/1968Van de Erve.pdf ER - TY - Generic T1 - Evidence of persistence or cross-contamination in cloud seeding experiments T2 - 36th Annual Western Snow Conference Y1 - 1968 A1 - Warburton, J.A. A1 - Young, L.G. KW - Cloud seeding effectiveness, Cloud seeding evaluation, Weather modification AB - One hundred and fifty samples collected during 1966-67 have been analyzed for silver content using thermal neutron activation methods. The samples were collected in five separate regions of the western United States. In two of the locations where extensive randomized silver iodide seeding was occurring, with seeding periods of one day, there is evidence of persistence of silver in the atmosphere in unseeded situations. Silver, in relatively high concentrations, was present in specific storms which yielded precipitation in an unseeded region. It is speculated that this silver originated in cloud seeding regions upwind of this unseeded area. Results also provide evidence that silver iodide released from the ground in one mountainous seeding area is not arriving in the target area precipitation. This is in strong contrast to results in two other similar seeding projects where high concentrations of silver are observed. JF - 36th Annual Western Snow Conference T3 - Proceedings of the 36th Annual Western Snow Conference PB - Western Snow Conference CY - Lake Tahoe, Nevada UR - sites/westernsnowconference.org/PDFs/1968Warburton.pdf ER - TY - Generic T1 - Estimating depth-load values spring alpine snowpack T2 - 35th Annual Western Snow Conference Y1 - 1967 A1 - Alford, D.F. KW - Snow quality, Snow research AB - An empirical relationship found to exist between integrated ramm hardness number, Rj, in Joules and Load, L, in g-sq cm at the base of the pack at the USA CRREL Goose Lake Snow Study Site is presented. It is suggested that the Rammsonde may offer a practical approach to the study of the snow water equivalent in areas where other techniques are not feasible. Considerable discussion is presented relative to highly technical difficulties of obtaining suitable snow samples in the study of snow loads of low density snow at below Zero ºC temperatures. Instrument procedures are discussed and the Rammsonde process data are plotted and tabulated. Similar data collected in Greenland studies are compared with those made in Southwestern Montana at Goose Lake. The so-called ‘PIT’ technique, where a large number of samples are taken from the walls of a pit dug to soil surface, is described. The average of a large number of samples are used. JF - 35th Annual Western Snow Conference T3 - Proceedings of the 35th Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho UR - sites/westernsnowconference.org/PDFs/1967Alford.pdf ER - TY - Generic T1 - Effect of temperature on winter runoff T2 - 35th Annual Western Snow Conference Y1 - 1967 A1 - Simons, W.D. KW - Hydrology flow analysis, Low flows AB - The effect of temperature on the October through March runoff of the Clark Fork River at St. Regis, Montana was examined in a preliminary manner. The runoff potential for each winter season of water years 1930 through 1963, was evaluated and compared to historical records. Temperature records for the October through March period of water years 1931 through 1960 for East Anaconda, Montana were used to develop two simple indices: (1) the minimum monthly mean temperature and (2) the number of consecutive days the maximum daily temperature was 32 deg F or lower. The critical flow of the 1936-37 year resulted from a runoff potential in the lower quartile in combination with the occurrence of record-breaking cold temperatures. JF - 35th Annual Western Snow Conference T3 - Proceedings of the 35th Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho UR - sites/westernsnowconference.org/PDFs/1967Simons.pdf ER - TY - Generic T1 - Estimating precipitation on a remote headwater area of western Alberta T2 - 33rd Annual Western Snow Conference Y1 - 1965 A1 - Curry, G.E. A1 - Mann, A.S. KW - Precipitation data analysis, Precipitation gage network AB - An extensive network of storage precipitation gages covering the upper reaches of the Saskatchewan river system is described in detail. Recent developments have increased the network to include snow survey courses in the higher elevations. Analysis of existing records has made possible the adjustment of data for under-catch at the storage gages, due to wind effects. Normal isohyetal maps covering the area have been constructed. Double mass diagrams and statistical methods were employed for this adjustment of data. Precipitation elevation relationships were also taken into account. JF - 33rd Annual Western Snow Conference T3 - Proceedings of the 33rd Annual Western Snow Conference PB - Western Snow Conference CY - Colorado Springs, Colorado UR - sites/westernsnowconference.org/PDFs/1965Curry.pdf ER - TY - Generic T1 - Evaluation of weather modification T2 - 33rd Annual Western Snow Conference Y1 - 1965 A1 - Kahan, A.M. KW - Evaluations, Weather modification AB - A review of various procedures of evaluating the effects of weather modification operations used in past years is presented. Indications are the operators have made elaborate claims by simple comparisons of precipitation data from the target area after seeding and the average precipitation from past years of record. In some cases average isohyetal maps have been used. Such tests are thought to be extremely insensitive to show the desired effects. Statistical methods using multiple regression analysis and based on resulting inflow to reservoirs or streamflow is more practicable and protects against bias. With all evaluations certain assumptions must be made, either statistical, or physical processes. Seven necessary assumptions are listed for consideration. Reference is made to reports by the advisory Committee on Weather Modification and the National Science Foundation Reports on weather modification, of which 195 references on the subject are listed. JF - 33rd Annual Western Snow Conference T3 - Proceedings of the 33rd Annual Western Snow Conference PB - Western Snow Conference CY - Colorado Springs, Colorado UR - sites/westernsnowconference.org/PDFs/1965Kahan.pdf ER - TY - Generic T1 - Engineering aspects of weather modification T2 - 33rd Annual Western Snow Conference Y1 - 1965 A1 - Zoff, D.O. KW - Engineering aspects, Weather modification AB - Engineering problems associated with the conception, design, field operations and data processing of weather modification programs. Examples taken from the Bureau of Reclamation program at Steamboat Springs, Colorado, with particular emphasis on snowrate sensor and diffusion instrumentation. JF - 33rd Annual Western Snow Conference T3 - Proceedings of the 33rd Annual Western Snow Conference PB - Western Snow Conference CY - Colorado Springs, Colorado UR - sites/westernsnowconference.org/PDFs/1965Zoff.pdf ER - TY - Generic T1 - Evaporation from a winter show cover in the Rocky Mountain Forest zone T2 - 32nd Annual Western Snow Conference Y1 - 1964 A1 - Bergen, J.D. A1 - Swanson, R.H. KW - Evporation, Research, Sublimation AB - Evaporation from a snowpack during winter temperatures is measured in an attempt to satisfy a theoretical energy balance formula of factors involved. Field laboratory equipment is used to test the theoretical computations. Formula derivation and data from field tests are shown. Explanations of the methods and procedures are discussed together with an analysis of the problems.A discussion by Mr. David M. Rockwood substantiates the theory involved and suggestions are offered. JF - 32nd Annual Western Snow Conference T3 - Proceedings of the 32nd Annual Western Snow Conference PB - Western Snow Conference CY - Nelson, British Columbia UR - sites/westernsnowconference.org/PDFs/1964Bergen.pdf ER - TY - Generic T1 - An economical total precipitation telemetering system T2 - 32nd Annual Western Snow Conference Y1 - 1964 A1 - Chadwick, D.G. A1 - Pearson, G.L. KW - Precipitation gages, Telemetry AB - A progress report is presented dealing with a telemetering system for collecting precipitation data from remotely located shielded storage precipitation gages in Utah. The system consists of a large capacity rain gage, charged with anti-freeze solution and mounted on a tower with shield. The gage is supported on a central spring support with potentiometer attached for varying the frequency of a battery operated transistor radio transmitting system. The radio is read by over-flight airplane 5000 to 7000 feet above the instruments. The present system is in continuous operation; however an 'On Call' system is being developed and would be triggered by operation from the airplane. Successful operation data are exhibited in three graphs. Cost estimates are included with pictures and schematic diagrams of the system are shown.Discussion by Glenn H. Castle. JF - 32nd Annual Western Snow Conference T3 - Proceedings of the 32nd Annual Western Snow Conference PB - Western Snow Conference CY - Nelson, British Columbia UR - sites/westernsnowconference.org/PDFs/1964Chadwick.pdf ER - TY - Generic T1 - Economic consideration of water yield forecasting for the Salt River Valley, Arizona T2 - 30th Annual Western Snow Conference Y1 - 1962 A1 - Moore, R.E. KW - Economics, Water supply forecasting AB - Snowmelt water provides the major portion of the annual runoff to the Salt River Project System. The worth of this runoff, equated to the basic snow survey data and resulting water yield forecast, is discussed in terms of some economic considerations. These considerations are emphasized from the standpoint of the application by a water user of such forecast information.In discussion Mr. Jesse D. Ellis describes his application of Mr. Moore's economic theories to the savings possible in power development by having advance knowledge of a possible 10 percent plus or minus average potential runoff into reservoirs by forecasting. JF - 30th Annual Western Snow Conference T3 - Proceedings of the 30th Annual Western Snow Conference PB - Western Snow Conference CY - Cheyenne, Wyoming UR - sites/westernsnowconference.org/PDFs/1962Moore.pdf ER - TY - Generic T1 - Effect upon irrigation of critical low-flow of the Rogue River T2 - 29th Annual Western Snow Conference Y1 - 1961 A1 - Shaffer, N.F. KW - Critical flows, Water rights, Water supply forecasting AB - Problems presented to an irrigation district manager when a critically low flow of water is forecast for the stream from which his district's supply is derived are discussed in detail. Economical problems arise either to obtain additional supplies from pumping or conserving the existing supply by rotation of demands and sometimes a loss of certain crops. The necessity of obtaining an accurate forecast of flows to the district supply point prior to occurrence so that plans can be made in advance is brought out in the discussion. JF - 29th Annual Western Snow Conference T3 - Proceedings of the 29th Annual Western Snow Conference PB - Western Snow Conference CY - Spokane, Washington UR - sites/westernsnowconference.org/PDFs/1961Shaffer.pdf ER - TY - Generic T1 - Economics of early season snow surveys T2 - 27th Annual Western Snow Conference Y1 - 1959 A1 - Hannaford, J.F. KW - Snow survey normals, Water supply forecasting AB - Snow surveys made prior to the optimum date of April first are shown to be economical in value to water users, depending upon the use made of the early season forecast. although snow surveys are expensive to make in some cases, the accuracy of the forecasts prepared from these data as compared to alternative forecasts based on other data is outstanding and well worth the expenditure. Purely graphical methods are used and illustrated by using the flows of the Kings River inflow to Pine Flat Reservoir, California. JF - 27th Annual Western Snow Conference T3 - Proceedings of the 27th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1959Hannaford.pdf ER - TY - Generic T1 - Evaluation of cloud seeding efforts in the southern Oregon Cascades, 1952-1957 T2 - 26th Annual Western Snow Conference Y1 - 1958 A1 - Barton, M. A1 - Calvin, L.D. KW - Forecasting, Water supply, Weather modification AB - Cloud seeding operations for The California Oregon Power company have been conducted by North American Weather Consultants for the past 7 years in the Southern Oregon Cascades. The purpose was to increase the mountain snowfall and consequently, the summer streamflow for the production of hydroelectric power. The seeding methods and the climate of the areas are discussed. Based on regression and isopercentile analyses of the data for the first 6 years of seeding, the following conclusions were reached. (1) the average April 1 snow water content for 1952-1957 showed a 3% increase over the expected amount. (2) The average November-March precipitation for the 6 seeding years showed a 2% increase over the expected amount, a nonsignificant increase. (3) The average April-July streamflow for 1952-57 was 4% higher than expected, a nonsignificant increase. (4) for 4 of the 6 seeded years, the highest percent of normal precipitation in the State has occurred in the Fremont-Paisley area, lending strong support to the thesis that a downwind effect exists beyond the target area. JF - 26th Annual Western Snow Conference T3 - Proceedings of the 26th Annual Western Snow Conference PB - Western Snow Conference CY - Bozeman, Montana UR - sites/westernsnowconference.org/PDFs/1958Barton.pdf ER - TY - Generic T1 - The economics of water supply forecasting T2 - 26th Annual Western Snow Conference Y1 - 1958 A1 - Dwyer, C.H. KW - Economics, Forecasting, Water supply AB - A discussion of the economic value of water supply forecasting is presented dealing with monetary values. It is pointed out that if 'Economics is the science concerning the production, management, and distribution of wealth', then truly water to the farmer, in irrigated areas, is true wealth. This depending entirely on the possibility of furnishing reliable information as to data relating to: too much water or too little, together with time of delivery. It is pointed out that floods can be a liability without the foreknowledge of occurrence, and a credit if proper facilities are available for water management and planning through accurate information. An actual shortage season is described on one irrigation district where a savings of $378,850 was saved by adhering to the water supply forecasts and applying good water management to produce good crops despite the water shortage and the season was not a total loss. JF - 26th Annual Western Snow Conference T3 - Proceedings of the 26th Annual Western Snow Conference PB - Western Snow Conference CY - Bozeman, Montana UR - sites/westernsnowconference.org/PDFs/1958Dwyer.pdf ER - TY - Generic T1 - Evolution in derivation of seasonal streamflow forecast procedures T2 - 26th Annual Western Snow Conference Y1 - 1958 A1 - Van Horn, O.B. KW - Electronic computers, Forecasting, Water supply AB - A streamflow forecast procedure for the Missouri River Basin, to meet the needs of the Corps of Army Engineers Division office at Omaha, Nebraska is described in detail. Snow survey and precipitation data were analyzed by automatic data processing system (ADPS). Problems encountered during the electronic computer developing the multiple regression equations are discussed, primarily the coding and decoding and negative values of multiple correlation coefficients. Tests were made for minimizing the effect of 'local Anomaly' and negative values are described. A system of dividing the Missouri Basin into snowmelt basins from predominantly rainfall basins proved satisfactory values for coefficients. The resulting scheme provided results well within the 20% limits. JF - 26th Annual Western Snow Conference T3 - Proceedings of the 26th Annual Western Snow Conference PB - Western Snow Conference CY - Bozeman, Montana UR - sites/westernsnowconference.org/PDFs/1958Van Horn.pdf ER - TY - Generic T1 - Establishing snow survey networks and snow courses for water supply forecasting T2 - 23rd Annual Western Snow Conference Y1 - 1955 A1 - Codd, A.R. A1 - Work, R.A. KW - Networks, Snow Courses, Water Supply Forecasting AB - The purpose of snow surveys and the planning of survey networks are discussed. Factors determining the type of snow course network, the number of snow courses, and measurement schedules are outlined. Criteria for the selection of the snow course location are examined, including; elevation, water production of the area, relation to other snow courses, accessibility, and the physical characteristics of the site. Conditions influencing the accuracy of snow, the number of snow samples taken, the relation between the snow course and its environment, and the marking of sampling points are considered.Discussion by J.H. Doughty-Davies and F.M. Veatch. JF - 23rd Annual Western Snow Conference T3 - Proceedings of the 23rd Annual Western Snow Conference PB - Western Snow Conference CY - Portland, Oregon UR - sites/westernsnowconference.org/PDFs/1955Codd.pdf ER - TY - Generic T1 - Effect upon seasonal runoff forecasts of measurement errors in basic data T2 - 22nd Annual Western Snow Conference Y1 - 1954 A1 - Dean, W.W. A1 - Frost, W.T. A1 - Kuehl, D.W. KW - Statistical analysis, Water supply forecasting AB - A study was made of random sampling errors inherent to hydrologic data used for statistical development of multiple-linear regression formula to forecast the probable season water supply. Random errors were induced into basic data of both the dependent and independent variables and multiple linear equations were developed. The usual statistical parameters of correlation coefficient and standard error were compared with those formulas developed where the obvious random errors were NOT induced. These tests indicated that the introduction of errors in the magnitude chosen did not cause any large effects in the regression equation. It is suggested that every effort be made to gather and use data without errors in measurement and keep hydrologic data up to standard. JF - 22nd Annual Western Snow Conference T3 - Proceedings of the 22nd Annual Western Snow Conference PB - Western Snow Conference CY - Salt Lake City, Utah ER - TY - Generic T1 - Evaluation of rain making experiments in Utah T2 - 22nd Annual Western Snow Conference Y1 - 1954 A1 - Hales, J.V. A1 - Hoffer, T.E. A1 - Peck, E.L. KW - Weather modification evaluation AB - After three years of operations a weather modification project is studied and an evaluation is made over an area covering 200 square miles in Southern Utah. Use is made of Electronic Data Processing equipment to evaluate precipitation data from 120,000 Weather Bureau observations of daily rainfall amounts from the state. The process involved a statistical comparison of data from within and without the target area, also the inter-relationship between stations. Many problems complicate the study: the changing of location of silver iodide generators, the addition of more generators, the silver iodide drifting out of the target area and effecting station records in remote areas. It became difficult to establish a constant set of guidelines for evaluation. The studies are continuing for reporting, provided funds are available.In discussion Mr. Boyd E. Quate pointed out the difficulties of evaluating cloud-seeding operations by virtue of so many projects in operation over the arid states that the long distance effect of silver iodide particles may affect precipitation on an inter-state basis. JF - 22nd Annual Western Snow Conference T3 - Proceedings of the 22nd Annual Western Snow Conference PB - Western Snow Conference CY - Salt Lake City, Utah ER - TY - Generic T1 - Evidence of man-made climate change T2 - 21st Annual Western Snow Conference Y1 - 1953 A1 - Krick, I.P. KW - Weather modification evaluation, Weather modification methods AB - Cloud seeding to produce additional snow water content in the snowpack of the Upper South Platte and Arkansas River Basins in Colorado is explained. Detailed meteorological and physics of cloud characteristics for cloud seeding are descried. Evaluation is based on statistical methods, using a 10 year period of snow surveys water content data prior to seeding and comparing the 3 years of seeding data of snow surveys conducted during this period. Claims are made that seeding increased the snowpack by 200% over the basic 10 years, while other basins to the south along the Rocky Mountains did not show this increase during the seeding of the last 3 years. Charts illustrate the 3 years of seeding operations and location of river basin target areas. In discussion Milton S. Sachs points out that good results are shown in increasing the snowpack by cloud seeding in the northwest along the Cascades and Rockies. He states that large scale operations are more affective and not so difficult to evaluate. JF - 21st Annual Western Snow Conference T3 - Proceedings of the 21st Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho ER - TY - Generic T1 - Estimating precipitation at San Francisco from concurrent meteorological variables T2 - 20th Annual Western Snow Conference Y1 - 1952 A1 - Jorgensen, D.L. KW - Evaluation of weather modification, Methods of weather modification, Weather modification AB - A study of meteorological factors responsible for producing rainfall is presented, and especially designed to develop a procedure for evaluating weather modification by the use of silver iodide generators. The main objective being to determine if rainfall would have occurred from a given set of atmospherical conditions without cloud seeding and if so, how much more was due to the artificial triggering. Upper-air masses at 400 and 700 mb. With open and closed low storm centers are plotted on scatter diagrams. Results are computed by probability theories and amounts of rainfall are snow. These data are compared to 12 and 24 hour amounts and monthly totals were computed by observed data.In discussion Dr. J. Neyman confines his remarks to the statistical probabilities and the procedures used in the paper and states that advance work will be forthcoming. JF - 20th Annual Western Snow Conference T3 - Proceedings of the 20th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California ER - TY - Generic T1 - The economic aspects of snow T2 - 17th Annual Western Snow Conference Y1 - 1949 A1 - Burdick, R.T. KW - Economics, Runoff, Snowmelt AB - Irrigation in many areas depends largely on water stored in the form of snow. The average precipitation during May to August at Montrose, Colorado is 37% during which period the flow in the Gunnison River is 67.4%. The delay of nearly 33% of the streamflow is attributed to snow accumulation. The result of experimental timber cutting at the Rocky Mountain Forest & Range Experiment Station at Fort Collins indicate that moisture stored can be increased approximately 25% by planned cutting on dense, high altitude forest lands. The Forest Service anticipates that timber cutting experiments may change the early snow melt and increase the streamflow through fall. Snow is an important economic consideration in the generation of power by streams. JF - 17th Annual Western Snow Conference T3 - Proceedings of the 17th Annual Western Snow Conference PB - Western Snow Conference CY - Denver, Colorado ER - TY - Generic T1 - Empirical methods for estimating snow melt rates T2 - 16th Annual Western Snow Conference Y1 - 1948 A1 - Wilson, W.T. KW - Runoff, Snowmelt, Statistical analysis, Water supply forecasting AB - A simple formula for predicting daily runoff from snow has been developed. The basis of the formula is that streamflow form melting snow is largely a function of antecedent streamflow, heat supply and time of year. These factors are obtained statistically from meteorological data. The formula gave results accurate within 9% when used in predicting daily flow from snow at the Central Sierra Snow Laboratory for the Castle Creek drainage basin during April and May, 1945. The time of year factor was omitted in this calculation.Discussion by Walter U. Garstka. JF - 16th Annual Western Snow Conference T3 - Proceedings of the 16th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada ER - TY - Generic T1 - Effect of high water table in exaggerating streamflow: 1942-44 Humboldt River Nevada T2 - 12th Annual Western Interstate Snow Survey Conference Y1 - 1944 A1 - Church, J.E. A1 - Boardman, H.P. KW - Forecast accuracy AB - An analysis of the 1942-43-44 seasonal streamflow forecasts in relation to obscure factors that upset the usual forecast accuracy. Considerable more streamflow occurred than forecast by about 120% above the normal flow, when snow survey measurements indicated only 70 to 90% snowpack. The percentage system of forecasting appears to have difficulty in aligning such factors as soil moisture and apparently high ground-water table. Ground-water levels measured in wells did not show a large percentage above normal The preceding fall rainfall and the rainfall during the runoff season were quite high and probably account for the high flows.Discussion is presented by W. G. Hoyt who forwards some analysis of the discrepancy. Reference is made to a previous analysis of the same situation in WSC Paper No. 159-43. JF - 12th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 12th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Berkeley, California ER - TY - Generic T1 - The effect of timber cutting in a lodgepole pine forest on the storage and melting of snow T2 - 12th Annual Western Interstate Snow Survey Conference Y1 - 1944 A1 - Wilm, H.G. KW - Forest management optimum water yield, Forest management timber cutting, Snowmelt AB - Experiments conducted in mature forest of lodgepole pine at Rocky Mountain Forest & Range Experiment Station in Colorado, show that planned cutting will increase the snow cover during the accumulation period. A total of 17.5 inches of water passed through the forest canopy on heavily cut-over plots, as compared with 13.33 inches in the un-cut forest. The accelerated melting rates of the cut-over plots were compensated by the excess snow stored initially. All experimental plots became bare at approximately the same time. Cutting is not advised in areas where floods and erosion are problems. (See also SIP U1839) JF - 12th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 12th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Berkeley, California ER - TY - Generic T1 - Effect of soil priming to spring runoff by fall precipitation on the upper Snake River T2 - 7th Annual Western Interstate Snow Survey Conference Y1 - 1939 A1 - Marr, J.C. KW - Antecedent precipitation, Fall precipitation, Snow data, Soil moisture, Water supply forecasting AB - The effect of fall precipitation as a soil priming factor in predicting irrigation water supply from April first snow survey data is presented. Graphical analysis are illustrated and discussed. Snow survey data at nine courses, and precipitation data for April, May and October at Moran, Wyoming, are tabulated and used in the analysis. Forecasts are determined from the graphs illustrated. Discussion by H.T. Gisborn, Lynn Crandle, O.W. Monson and J.E. Church are included. JF - 7th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 7th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Spokane, Washington ER - TY - Generic T1 - The expanded program of the United States Weather Bureau in snow work T2 - 5th Annual Western Interstate Snow Survey Conference Y1 - 1937 A1 - Bernard, M. KW - Network, Precipitation gage AB - Mountain snow surveys for the benefit of irrigation were suggested in 1909 and have been made annually since 1911 on an increasing number of watersheds. The influence of elevation on snowfall is discussed. Precipitation stations will be equipped with storage snow gages and their present number supplemented to give a well distributed network in which elevation, aspect and individual needs of the various basins will be considered. The development of the storage gage is presented. The advantage of the snow storage gage s basin snowfall samplers are enumerated. Streamflow forecasting from snow surveys is discussed. Recommendations are made to overcome the deficiencies of hydrologic research and include improvements of snowfall and snow depth measurements, determination of relations between factors causing snow to melt, and evaluation of surface conditions controlling the losses to runoff from melting snow. JF - 5th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 5th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Davis, California ER - TY - Generic T1 - Establishing snow courses for representativeness, permanence, and continuity of record T2 - 5th Annual Western Interstate Snow Survey Conference Y1 - 1937 A1 - Clyde, G.D. KW - Snow course location AB - Snow courses should be located in uniform and fairly well protected areas such as, level open forests, parks, or closed basins above winter melting lines. The ground surface should not show signs of standing water and far enough from creeks or stream banks that there is no chance of early flooding. Sample intervals are usually 50 to 100 feet apart. The number of samples usually 10 or 20 are sufficient. Better to have several courses of 10 samples at intervals of altitude than one long course in a basin. It is recommended that courses be accurately mapped, marked cleared, and described on data sheets. Snow survey record sheets should be kept up to date. Consistent records can be obtained more readily if courses are accessible, or if suitable shelter cabins are available. Pictures and sketch maps of courses are shown; also an assortment of data collections sheets, and marker signs for courses. JF - 5th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 5th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Denver, Colorado ER - TY - Generic T1 - Eastern Sierra snow sports T2 - 5th Annual Western Interstate Snow Survey Conference Y1 - 1937 A1 - Diebert, G. KW - Winter sports areas AB - A description of the winter sports areas along the Eastern slopes of the Sierra in the neighborhood of Bishop, California. Ski slopes with tows are operating at Bishop Pass, Mt. Tom, Denderberg Mt., Conway Summit and at the Mammoth Lakes and Pass area. Accommodations are available. New areas are being contemplated with chair lifts. JF - 5th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 5th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Davis, California ER - TY - Generic T1 - Establishing first year-normals on the basis of accumulated showfall snd some forecasts from runoff ratios T2 - 5th Annual Western Interstate Snow Survey Conference Y1 - 1937 A1 - Farrow, R.C. KW - Statistical analysis, Water supply forecasting AB - Three snow courses (one in each area) were laid out in 1937 at Glacier in the Selkirks, at Field in the Rockies, and at Fernie in the Southern Canadian Rockies. The location are near various precipitation stations whose data can be related to runoff at higher elevations. Sampling data from the 3 courses, the method used in obtaining a tentative first year normal, the mechanics of forecasting used, and the application of the forecast to points further downstream by use of runoff ratio factors are discussed. The percentage method is compared with the density method in establishing first-year snow course normals. It is concluded that a relationship between snowfall data and runoff is evident and that precipitation during runoff does not affect runoff. A refutation by Carl Elges of the density method is contained in the discussion. (See also SIP U1695 and WSC 35-37). JF - 5th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 5th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Davis, California ER - TY - Generic T1 - Economic value of snow surveying for the Los Angeles aqueduct T2 - 5th Annual Western Interstate Snow Survey Conference Y1 - 1937 A1 - Phillips, J.E. KW - Economics of municipal water supply, Economics of snow surveys AB - The benefits derived from snow surveys are often difficult to evaluate financially. The City of Los Angeles, Department of Water and Power, shows well planned operations by using snow survey data for reservoir regulation for municipal water supply from the Owens River aqueduct; for requirements of possible pumping operations for supplementary water needs, also for water-spreading operations to build up ground water supplies through irrigation on city owned lands leased to farmers along the upper reaches of the Owens River. Plans for lease rentals and crops to be planted are based on knowledge gained from snow survey data. JF - 5th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 5th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Davis, California ER - TY - Generic T1 - The effect ot soil-absorption on snow survey forecasting of streamflow T2 - 4th Annual Western Interstate Snow Survey Conference Y1 - 1936 A1 - Boardman, H.P. KW - Soil absorption, Statistical analysis, Water supply forecasting AB - Snow precipitation producing run-off on the eastern slope of the Central Sierra is described. The total precipitation or absorption losses cannot be quantitatively determined, and soil absorption losses as well as evaporation loss must be considered for large basins. It is believed that soil absorption and other losses are constant under otherwise equal conditions and that the run-off is directly proportional to the amount of winter precipitation. Snow survey and runoff of the Truckee and Tahoe basins are tabulated and discussed for 1921-33. The insertion of pipes in the ground, the recording of fluctuations of the ground water level, and intensified precipitation and temperature studies in high altitudes are recommended. JF - 4th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 4th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Pasadena, California ER - TY - Generic T1 - Extension of normals by precipitation-data and by comparison with another stream T2 - 4th Annual Western Interstate Snow Survey Conference Y1 - 1936 A1 - Parker, G.L. KW - Normals - streamflow, Water supply forecasting AB - A narrative is presented describing possible procedures for estimating the streamflow NORMALS, (Monthly, Seasonal), for gaging stations with short periods of record. By virtue of the great variation of precipitation in the high altitudes and the valley stations and various orographic effects from basin to basin aspect, there seems to be very little correlation in this procedure of extending runoff normals. There is apparently sound procedures to correlate stream gage stations where characteristics are similar. The soundest procedure is to establish precipitation stations and snow course surveys in the basin and create a reliable record of streamflow and be patient. JF - 4th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 4th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part II: CY - Pasadena, California ER - TY - Generic T1 - Evaporation at high altitudes and latitudes T2 - 2nd Annual Western Interstate Snow Survey Conference Y1 - 1934 A1 - Church, J.E. KW - Evaporation from snow surface, Evaporation from tree accumulation AB -

A report of a study dealing with evaporation from snow-fields and tree accumulation beginning in 1910 on Mt. Rose, Nevada, (10,800) and in the Lake Tahoe Basin, 6225 altitude. A description of field equipment and procedures of measurement is presented. Tabulations of hourly and daily data are shown in the 24 tables. Comparisons of data are discussed in the text, together with discussion of troubles and solutions to improve the measurements. The author has included data collected while on the Hobbs Exposition to the Ice Cap of Greenland in 1926. Evaporation from snow surfaces were made at that time and data with discussion of resulting information is also included.

JF - 2nd Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 2nd Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions 15: CY - Berkeley, California ER -