Sparse monsoon rainfall last summer and spotty snowfall this winter have combined to dramatically worsen the drought across the West in the past year, and spring snowmelt won’t bring much relief.
Critical April 1 measurements of snow accumulations from mountain ranges across the region show that most streams and rivers will once again flow well below average levels this year, stressing ecosystems and farms and depleting key reservoirs that are already at dangerously low levels.
As the climate warms, it’s likely that drought conditions will worsen and persist across much of the West. Dry spells between downpours and blizzards are getting longer, and snowpack in the mountains is starting to melt during winter, new research shows. The warming atmosphere may also be suppressing critical summer rains from the western monsoon, a seasonal shift in wind direction often accompanied by precipitation.
A year ago, when California and Colorado experienced their worst fire seasons on record, drought conditions spanned about half the West, and no areas categorized as “extreme” or “exceptional.” But going into this year’s dry season, about 90% of the region is now in drought, with 40% in those two most severe categories.
At the end of March, the U.S. Drought Monitor showed exceptional drought spreading across roughly half of Nevada, Arizona, Utah and New Mexico, and extending up to northern Colorado. Utah was persistently dry from January 2020 through January 2021, with some welcome snow piling up in just the past few weeks, but too little and too late to stop the state’s steady drying. California’s snowpack is about half of average, according to that state’s April 1 snow survey.
“Everything is looking below to much below average,” said Cody Moser, senior hydrologist for the Colorado Basin River Forecast Center. Although everyone is hoping for a wet spring, he said, “we’re not holding our breath for something like that.”
Forecasters expect this year’s annual flow into Lake Powell, a key Colorado River reservoir that helps distribute water to 40 million people and vast croplands in the Southwest, will only be around 45% of normal.
New studies show lengthening dry spells, earlier snowmelt
This year’s parched conditions aren’t surprising to…