Western snowpack melts early, little remains

West-wide snowpack has mostly melted, according to data from the fifth 2015 forecast by the United States Department of Agriculture’s Natural Resources Conservation Service. “Across most of the West, snowpack isn’t just low—it’s gone,” NRCS hydrologist David Garen said. “With some exceptions, this year’s snowmelt streamflow has already occurred.” Garen said that for much of the western US, the snowpack at many of the stations is at or near the lowest on record. Months of unusually warm temperatures hindered snowpack growth and accelerated its melt. “It’s been a dry year for the Colorado River,” NRCS hydrologist Cara McCarthy said. “Snowmelt inflow into the Lake Powell Reservoir is forecast at 34 percent of normal.” The Lake Powell Reservoir supplies water to much of the Southwest, including Las Vegas, Los Angeles and southern Arizona. “We only forecast streamflow from current conditions,” McCarthy said. “Spring and summer rains might relieve areas that are dry.” In Western states where snowmelt accounts for the majority of seasonal water supply, information about snowpack serves as an indicator of future water availability. Streamflow in the West consists largely of accumulated mountain snow that melts and flows into streams as temperatures warm in spring and summer. National Water and Climate Center scientists analyze the snowpack, precipitation, air temperature and other measurements taken from remote sites to develop the water supply forecasts...more