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
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.