Above-normal temperatures combined with paltry precipitation levels have led to rapid snowmelts across the U.S. West — reducing water supplies for the spring and summer, federal meteorologists are warning.
Nearly all Western basins are now experiencing a late season “snow drought,” or a period of unusually minimal snow accumulation for a given point in the year, according to reports released by the National Integrated Drought Information System on Tuesday.
These dismal conditions are affecting almost the entire region, despite the fact that many monitoring stations showed above-average snow water equivalent — the amount of water contained in snow — during the accumulation season, the authors noted.
The meteorologists attributed that downturn to record early “melt out” in areas of Nevada, Colorado, Utah and New Mexico.
The rapid disappearance of snow and subsequent evaporation, dubbed the “thirst of the atmosphere,” has also been drying out soil and vegetation — creating prime conditions for an early start to fire season, the report warned.
“Snowmelt this time of year is common, but such rapid melt rates are not normal,” the meteorologists stated.
In some cases, they explained, above-normal temperatures can also cause snow to sublimate — transform from a solid to a gas — and hamper the amount of runoff available in streams and reservoirs.
The Intermountain West in particular is enduring a continued expansion and intensification of drought, with the U.S. Drought Monitor indicating that 27 percent of the region is in “extreme or exceptional drought,” as opposed to just 20 percent two months ago.
Water supply forecasts for both the Colorado River and Rio Grande basins have plummeted since previous projections issued on April 1, due to a dearth in April showers, the report authors explained.
“Existing drought conditions are likely to persist through summer, along with warmer-than-normal temperatures,” the meteorologists added.
