By Ann McCreary
The hefty mountain snowpack that blanketed mountains around the Methow Valley at the beginning of April has rapidly melted away during the warm weather of recent weeks.
On April 1, the snowpack in the upper Columbia River basin, which includes the Methow Valley, was 134 percent of normal. As of Monday (April 25), the snowpack — in terms of the water contained in the snow — had dropped to only 63 percent of normal.
“We lost more than half of what we had” at the beginning of the month, said Scott Pattee, water supply specialist for the National Resources Conservation Service.
“The majority of Snotel [snowpack measurement] sites in the upper Columbia have melted out,” Pattee said Monday. “Two weeks ago when we had that heat wave it really tipped the bucket over.”
As of Monday, temperatures have been 70 degrees or higher on more than half the days during April, reaching into the mid-80s on a few days.
Temperatures measured at the National Weather Service (NWS) station in Winthrop were running 7.4 degrees higher than average for the month as of April 25, said John Livingston, NWS meteorologist in Spokane.
The warm temperatures and resulting rapid snowmelt filled rivers and streams throughout the region. The Methow River measured at Pateros was running at 11,200 cubic feet per second (cfs) on April 25, compared to a mere 3,600 cfs on the same date last year, Pattee said.
The Methow River probably hit its peak steam flow for the year on April 22, following several days of 70-plus temperatures. The river was running at 16,300 cfs on that date at Pateros, about 2,000 cfs below flood stage, Pattee said. The record high measurement for the Methow River at Pateros is 28,800 cfs on May 31, 1972, he said.
After two years of drought in Washington, state water supply watchers were encouraged by last winter’s healthy snowpack. The state Department of Ecology forecasts the volume of runoff between April and September to be near or above normal levels.
Short supply again
The rapid snowpack melt-off, however, could mean that water will again be in short supply by the end of summer, Pattee said. If most of the normal volume of runoff occurs between now and June, water for agriculture, recreation, fish and wildlife could once again be scarce, he said.
“I have a little bit of concern for streamflows for the tail-end of the season — late August and September,” Pattee said.
“I don’t know that we’re going to be dealing with drought. It really depends on how hot and dry the summer is. We’re not completely out of the woods, especially for basins like the Methow where you have no reservoir storage,” Pattee said.
“It [the snowpack] is coming off faster than normal and we’re going to run out of snow before the summer is over,” he said.
Only a couple of Snotel sites in the upper Columbia basin still have snow, Pattee said. One is at Hart’s Pass, which measured 85 inches on Monday — 92 percent of normal for the date.
The faster-than-normal snowpack melt is due in large part to the warmer-than-normal winter temperatures last winter, which were about 2.5 degrees above normal, Pattee said.
“We normally get those deep freezes” that solidify and preserve the mountain snowpack, but that wasn’t the case last winter, he said. The warmer winter temperatures meant the snowpack remained very wet and was easier to melt.
“It doesn’t take as much energy to get the melt started. We’re over the hump really, as fast as it is coming off.”
The NWS long-range outlook for Washington predicts above-normal temperatures this summer, said meteorologist Livingston. The weather service drought monitor currently projects no drought in Washington this year except minor drought around the Tri-Cities area, said.
The National Interagency Fire Center predicts wildfire activity to be normal for Washington and Oregon through July, which is as far as the forecast extends.