SPOKANE — About 14 percent of the Spokane River basin’s mountain snowpack has melted away in recent weeks because of unseasonably warm nighttime temperatures.
The Spokesman-Review reports that temperatures in the mountains have been 10 to 15 degrees warmer than usual at night.
Researchers say warmer nights are a trend consistent with climate change, and one that could have serious long-term ramifications for Northwest snowpack and summer water supplies.
On Friday, the low temperature at Mullan Pass was 46 degrees, a full 20 degrees warmer than normal for the 6,000-foot-elevation mountain pass near the Idaho-Montana line.
Mountain snowpack is an important source of water in the summer as it slowly melts. But a fast melt can lead to drought conditions.
On Monday, snowpack for the Spokane River basin was about 81 percent of normal for this time.
In addition to less snow, “we just never got the cold snaps that deep freeze the snowpack,” said water scientist Scott Pattee of the Natural Resources Conservation Service.
According to the National Weather Service, recent weather patterns are likely to continue into June. The three-month forecast calls for an increased chance of warmer-than-normal temperatures, with a slight increase in the chance of below-normal precipitation.
Last summer’s drought was a wake-up call for the Northwest in understanding how temperature affects water supply, said state climatologist Nick Bonds.
“It wasn’t a drought caused by lack of precipitation,” Bonds said. “It was a temperature-caused drought. It rained a lot more than usual in the mountains, and we didn’t have the snow.”
“We’d never seen anything quite like last year, and we’re grateful we’re not getting a repeat,” Bonds said. But, “it’s perhaps a taste of what will be happening more often in future decades.”
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