That’s raising early questions about water supplies across the West, which rely heavily on mountain snow to slowly melt and replenish rivers, reservoirs and groundwater through spring and summer.
Federal data shows that snow cover across the West is at a record low for this time of year. In parts of Arizona, Colorado, New Mexico, Utah, Idaho, Nevada and Wyoming, snowpacks are holding less than half the water they typically would.
“They have extremely low snowpacks,” said Dan McEvoy, a climatologist at the Desert Research Institute. “And that's primarily due to the extremely warm temperatures we've had so far this winter, which isn't isolated, really, anywhere — it's spread across the entire Western U.S.”
Those warm conditions have also shifted precipitation away from snow and toward rain.
“Rain during the middle of the winter isn't uncommon, that happens all the time,” McEvoy said. “But having it be this warm and this much rain is not common.”
McEvoy said the dry start is especially critical for the Colorado River Basin, which supplies water to tens of millions of people across the West.
Snowpack in the basin’s headwaters acts as a natural reservoir, releasing water gradually as temperatures warm. When more winter precipitation falls as rain instead of snow, that water tends to run off quickly, leaving less available later in the year.
McEvoy said it’s still early in the snow season, and late-winter storms could help improve conditions.
This story was produced by the Mountain West News Bureau, a collaboration between KUNR, Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio, KJZZ in Arizona and NPR, with additional support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
