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 - Variation of snow water equivalent and streamflow in relation to the El Nino/southern oscillation T2 - 59th Annual Western Snow Conference Y1 - 1991 A1 - Koch, R.W. A1 - Buzzard, C.F. A1 - Johnson, D.M. KW - El Nino, SOI, Water supply forecasting AB - Snow water equivalent (SWE), precipitation and seasonal streamflow for selected locations throughout the western United States were related to an index of the El niño/Southern Oscillation (ENSO). The strongest relations were observed when either the summer or fall averaged Southern Oscillation Index (SOI) was correlated with the maximum SWE, winter season precipitation and streamflow during the subsequent runoff season. These results suggest that the SOI can be used as a predictor of both SWE and streamflow as early as October each year with varying degrees of confidence. The magnitude of the correlations were quite variable throughout the western U.S. with the strongest associations observed in the Pacific Northwest. During El niño events, SWE, precipitation and streamflow tend to be below normal. When the opposite condition, often called La Nina, occurs SWE, precipitation and streamflow tend to be above average. These results have some important implication in water supply forecasting. 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/1991Koch.pdf ER -