The western U.S. snowpack is melting earlier than usual, according to data from the fourth 2015 forecast compiled by the USDA’s Natural Resources Conservation Service (NRCS).
NRCS Hydrologist David Garen said, “Almost all of the West Coast continues to have record low snowpack. March was warm and dry in most of the West. As a result, snow is melting earlier than usual."
Historically, April 1 is the peak snowpack. This year, NASS says the peak came earlier. Little snow accumulated in March, and much of the existing snow has already melted.
“The only holdouts are higher elevations in the Rockies,” said Garen. “Look at the map and you'll see that almost everywhere else is red.”
Red indicates less than half of the normal snowpack remains.
A consequence of the early snowmelt is that western states will have reduced stream flow later this spring and summer.
In western states where snowmelt accounts for the majority of seasonal water supply, NASS says information about snowpack serves as an indicator of future water availability.
Stream flow 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.
Since 1939, USDA has conducted snow surveys and issued regular water supply forecasts.
Other resources on drought include the U.S. Drought Monitor.