Rains that break droughts more rare in U.S. West
BILLINGS, Mont. — Rainstorms grew more erratic and droughts much longer across most of the U.S. West over the past halfcentury as climate change warmed the planet, according to a sweeping government study released this week that concludes the situation is worsening.
The most dramatic changes were recorded in the desert Southwest, where the average dry period between rainstorms grew from about 30 days in the 1970s to 45 days between storms now, said Joel Biederman, a research hydrologist with the U.S. Department of Agriculture Southwest Watershed Research Center in Tucson, Ariz.
The consequences of the intense dry periods that pummeled areas of the West in recent years were severe — more intense and dangerous wildfires, parched croplands and not enough vegetation to support livestock and wildlife. And the problem appears to be accelerating, with rainstorms becoming increasingly unpredictable, and more areas showing longer intervals between storms since the turn of the century compared to prior decades, the study concludes.
The study comes with almost twothirds of the contiguous U.S. beset by abnormally dry conditions. Warm temperatures forecast for the next several months could make it the worst spring drought in almost a decade, affecting roughly 74 million people across the U.S., the National Oceanic and Atmospheric Administration said.
Water use cutbacks, damaged wheat crops, more fires and lower reservoirs in California and the Southwest are possible, weather service and agriculture officials have warned. Climate scientists are calling what’s happening in the West a continuation of a “megadrought” that started in 1999.
Northwestern states were largely spared from the accelerating cycles of drought. The researchers observed higher annual rainfall totals and shorter drought intervals in Washington, Oregon, Idaho and portions of Montana, Wyoming and the Dakotas.