Implementation of the Snow Estimation and Updating System (SEUS) in the Clearwater River Basin, Idaho

The Snow Estimation and Updating System (SEUS) was developed by the National Weather Service (NWS) to generate real-time gridded snow water equivalent estimates using ground-based and airborne snow data collected over the western United States. These gridded snow water equivalent estimates incorporate the spatial variability of the snowpack induced by orographic effects in the West. The estimates of snow water equivalent are used for hydrologic forecasting. In previous years, the SEUS has been implemented in portions of the Colorado River Basis and the results used for water supply forecasting.The 1995 snow season included some enhancements to the way the SEUS methodology was implemented to continue to improve the snow water equivalent estimates generated. Some improved data layers were added including seasonal precipitation layers developed using Precipitation-elevation Regressions on Independent Slopes Model (PRISM). This paper examines the effect of including airborne data on the snow water equivalent estimates. The impact of using satellite areal extent of snow cover to estimate the location of the snow line and its effect on the snow water equivalent is also examined. The NWS is interested in implementing the SEUS under a variety of physiographic and hydrologic regimes. The SEUS was implemented in the Clearwater River basin of Idaho where a more maritime climate provides a significant amount of moisture and where the elevations are not as extreme as they are in other portions of the Colorado Basin.