Methow River streamflow expected to be 91%
With spring just a few days away, the high-elevation mountains around the Methow Valley are holding a respectable snowpack, despite an unusually dry February throughout Washington state.
At Harts Pass above the Methow Valley, elevation 6,490 feet, snowpack is about 113% of normal as of mid-March. But it’s a different story at lower elevations around the valley, said Scott Pattee, water supply specialist at the Natural Resources Conservation Service (NRCS).
“Manual snow surveys in and around the Methow for the first of March weren’t as promising as Harts Pass,” Pattee said.
“The Mazama snow course [multiples sites where snow is measured manually] was reported to be almost bare in spots and only sported 51% of normal. The Loup Loup campground course was 62% and Starvation Mountain was 85%. Most conditions were also reported to be in a near spring-like state. Elevation is certainly a large factor this year,” Pattee said.
Snowpack readings at the beginning of March showed the Methow River basin at 93% of normal, according to a monthly water-supply report issued by the NRCS. That compares to a snowpack of about 130% of normal at the same time last year.
Mountain snowpack is important, especially in dry regions like central and eastern Washington, because it stores large amounts of water that is released as snow melts, providing essential water for agriculture, rivers and fish through the summer and fall. Snowpack is measured in snow-water equivalent, which reflects the amount of water contained in the snow.
“February was an extremely dry month,” said Pattee. That meant little growth in the mountain snowpack, despite temperatures that were lower than normal throughout most of the state.
However, an “atmospheric river” flowed into Washington on Feb. 27-28, soaking the state with record rain and adding to the snowpack in some mountain areas, particularly in the colder, higher-elevation North Cascades.
Rain affected snowpack
Heavy snow at higher elevations forced closures of mountain passes during the first part of the storm. But precipitation turned to rain on the second day, resulting in river flooding and road closures due to landslides and avalanches, the Washington State Meteorologist’s office reported.
Some lower-elevation mountains lost snowpack when the precipitation turned to rain. However, many watersheds have close to normal snowpack, “thanks to the head start received in late December and early January,” according to the state meteorologist’s monthly report.
Most of the snow this year was delivered in three storms in December, January and February. Between those storms were long dry spells, and “the lower-elevation stuff didn’t stick around. We got warm weather that melted it off,” Pattee said.
“It’s been one of those odd winters. We haven’t received the lower-elevation snow we usually do. We were dry as a bone through the month of February,” he said. “If you look at the historic numbers… for January and February and most of March, we should be getting snow every day. We’re starting off the month of March already dry.”
However, the ample snowpack at higher elevations is “what’s important” in providing water during the dry summer and fall months, Pattee said. Streamflow in the Methow River, fed by melting snow, is forecast to be about 91% of normal from April through September, according to NRCS. “That’s in the normal range,” Pattee said.
Due to the generally dry February, moderate to extreme drought continues in eastern Washington, reflecting long-term precipitation deficits that have yet to fully recover, according to the state meteorologist. On the state’s drought map, most of the Methow Valley lies within an area classified as “abnormally dry” that borders an area of “moderate drought” extending east.