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February Snow, Cold Helps Make Up For January; Basin Water Supply Forecast 111 Percent Of Normal
Posted on Friday, March 02, 2018 (PST)

After a January meltdown across much of the Columbia Basin, February delivered a surge in cooler temperatures and precipitation, supplementing the snowpack and improving the streamflow forecast for the region.


February “did bring us some relief in our snowpack numbers,” said Kevin Berghoff, a hydrologist with the Northwest River Forecast Center in Portland. However, Berghoff added during a briefing on Thursday that snowpack in the southern parts of Oregon and Idaho “is well below normal.”


There is a considerable contrast in seasonal precipitation this year compared to last year. In the Upper Columbia, precipitation was at 109 percent compared to 115 percent at this time last year; in the Snake River Basin, it’s 91 percent of normal compared to 136 percent; and in the Columbia River above The Dalles Dam, it’s 100 percent compared to 119 percent.


On the temperature side, Berghoff showed slides depicting a remarkable transition from well above-average temperatures across the Columbia Basin states in January to a much cooler than-average February, with the exception of southern Idaho.


“So there is hope in the forecast for the snowpack to rebound,” Berghoff said, pointing out how snowpack numbers have been restored to above-average conditions in the northern Cascades and in the northern parts of Idaho and northwest Montana as of March 1.


The Daily Inter Lake in Kalispell reported this week that northwest Montana’s Flathead Valley received 25.6 inches of snowfall in February, bringing the seasonal snowfall to 78.1 inches, well above the historic average of 44.8 inches for the end of the month.


The Whitefish Mountain Resort is boasting that it officially surpassed 300 inches of snowfall on The Big Mountain Feb. 24, bringing the settled base at the summit to 149 inches, or about 12.5 feet. It is the deepest base depth recorded at the summit in the ski area’s history.


But the snow came with cold, sometimes sub-zero temperatures during February.


Berghoff cited information from NOAA’s Climate Prediction Center showing a one-month outlook for wetter-than-average weather across the entire Columbia Basin; and a three-month outlook that is the same, excluding Oregon and Idaho.


Temperatures, meanwhile, are projected to be cooler-than-average across the entire basin over the next month, with much cooler weather anticipated in southeast Oregon; and over the next three months, cooler-than-average weather with the exception of southern Oregon and Idaho.


The water supply forecast, April through September, puts the Columbia River at Mica Dam at 109 percent of the 30-year average; the Kootenai River at Libby Dam, 107 percent; the Coeur d’ Alene River at Lake Coeur d’ Alene, 119 percent; the South Fork Flathead River at Hungry Horse Dam, 140 percent; the Clark Fork River upstream from Missoula, 178 percent; the Bitterroot River at Missoula, 132 percent; the Pend Oreille River, 128 percent; the Columbia River at Grand Coulee Dam, 115 percent.


The North Fork Clearwater River is expected to be at 119 percent; the Lower Snake River at Lower Granite Dam, 106 percent; the Lower Columbia River at The Dalles, 111 percent.


Water supply continues to taper down in the Cascades, from north to south. The April through September water supply forecast is 108 on the Skagit River, 95 percent on the Green River near Hanson Reservoir, 104 percent on the Cowlitz River, 83 percent on the North Santiam at Mehama, 75 percent on the Willamette River near Salem, and 66 percent of the historic average on the Rogue River.


Berghoff said water supply forecasts in Montana’s Clark Fork, Bitterroot and Flathead basins are ranked in the top 10 for the 1971 to 2017 period of record.


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The Columbia Basin Bulletin, Bend, Oregon. For information or comments call 541-312-8860.
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