Precipitation
2015, an unusually warm year...
Most of this winter, temperatures have persistently remained above to much above normal across much of the West. This has had a dramatic effect on the snowpack. This was well-noted in the Cascades and Sierra Nevada where the snowpack was much below normal for most of the winter. The Sierra Nevada precipitation for the water year (Oct. 1 - today) has remained well below normal. A few cool storms in the Cascades have resulted in small improvements in the snowpack conditions in this region. The overriding influence in these unusual circumstances of having a low snowpack but near normal precipitation is the persistent warm temperatures that have dominated the snowpack processes.

Freezing levels for most storm events have remained well above the elevation of many SNOTEL sites. The near to slightly below average water year precipitation (see map on page 5), especially in the Cascades of Oregon and Washington, has helped to improve any soil moisture, groundwater, and reservoir deficits. Warm temperatures and very little precipitation in the Sierra Nevada have provided for an extreme record-breaking snow season. Any precipitation that has fallen across the region has helped to offset the current effects of the low snow conditions that these areas have experienced but may not be enough to offset future deficits in snowmelt runoff for spring and summer streamflow.

In the West, the SNOTEL precipitation percent of normal map shows declining conditions from last week for most basins, with only a few areas in the normal range for this time of year. The exceptions are southern Wyoming, northeastern Utah and most of Colorado, where recent storms have improved the conditions for April.

For a more comprehensive report, visit this site:
http://www.wcc.nrcs.usda.gov/ftpref/support/drought/dmrpt-20150423.pdf