Rapid Snow Melt-Off In American West Stuns Scientists

Scientists say extreme March heat caused an unusually rapid collapse of snowpack across the American West that’s leaving major basins at record or near-record lows. “This year is on a whole other level,” said Dr Russ Schumacher, a Colorado State University climatologist. “Seeing this year so far below any of the other years we have data for is very concerning.” The Guardian reports: […] The issue is extremely widespread. Data from a branch of the US Department of Agriculture (USDA), which logs averages based on levels between 1991 and 2020, shows states across the south-west and intermountain west with eye-popping lows. The Great Basin had only 16% of average on Monday and the lower Colorado region, which includes most of Arizona and parts of Nevada, was at 10%. The Rio Grande, which covers parts of New Mexico, Texas and Colorado, was at 8%. “This year has the potential of being way worse than any of the years we have analogues for in the past,” Schumacher said.

Even with near-normal precipitation across most of the west, every major river basin across the region was grappling with snow drought when March began, according to federal analysts. Roughly 91% of stations reported below-median snow water equivalent, according to the last federal snow drought update compiled on March 8. Water managers and climate experts had been hopeful for a March miracle — a strong cold storm that could set the region on the right track. Instead, a blistering heatwave unlike any recorded for this time of year baked the region and spurred a rapid melt-off. “March is often a big month for snowstorms,” Schumacher said. “Instead of getting snow we would normally expect we got this unprecedented, way-off-the-scale warmth.”

More than 1,500 monthly high temperature records were broken in March and hundreds more tied. The event was “likely among the most statistically anomalous extreme heat events ever observed in the American south-west,” climate scientist Daniel Swain said in an analysis posted this week. “Beyond the conspicuous ‘weirdness’ of it all,” Swain added, “the most consequential impact of our record-shattering March heat will likely be the decimation of the water year 2025-26 snowpack across nearly all of the American west.” Calling the toll left by the heat “nothing short of shocking,” Swain noted that California was tied for its worst mountain snowpack value on record. While the highest elevations are still coated in white, “lower slopes are now completely bare nearly statewide.”