Warm temperatures in February contributed to further snowpack decline in the Cascades and Sierra Nevada, according to data from the third 2015 forecast by the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS). Snowpack in Nevada, Utah and Idaho also fell further behind normal.
"Nearly a third of our SNOTEL sites in the Cascades and Sierra Nevada are reporting the lowest snowpack ever measured," NRCS hydrologist Cara McCarthy said. "For the first time, some sites were snow-free on March 1. These areas can expect reduced summer streamflow."
Recent storms helped relieve dry conditions in the Southwest, NRCS said. However, drought conditions persist in California, Nevada and Utah, as well as in parts of Arizona, New Mexico and Colorado. Areas in Washington and Oregon also remain in drought.
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.
The Cascades of Oregon and Washington have received near normal levels of precipitation this water year, but it's mostly fallen as rain instead of snow. Rainfall captured by reservoirs in those states will help mitigate dry spring and summer months, NRCS said.
NRCS monitors conditions year-round and will continue to issue monthly forecasts until June. The water supply forecast is part of several USDA efforts to improve public awareness and mitigate the impacts of drought and other extreme weather events.
Since 1939, USDA has conducted snow surveys and issued regular water supply forecasts. Other resources on drought include the U.S. Drought Monitor. For information on USDA's drought efforts, visit the USDA Disaster and Drought Information webpage.
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