Snowpack, water supply near normal

Despite the influences of an El Nino weather pattern that was expected to lead to a warmer, drier winter in the Pacific Northwest, this year is shaping up to be better than last year in terms of water supply forecasts.

“This year we have seen pretty warm temperatures but not as bad as last year,” said Kevin Burghoff, a forecaster with the Northwest River Forecast Center in Portland during a Thursday teleconference.

Last year at this time, there were “excessively warm temps that did a number on our snowpacks,” he said, adding that snowpacks this year are looking much better in Oregon and Washington. And that has led to promising streamflow forecasts through August.

Seasonal precipitation from last October through March 1 comes in at 104 percent of the 30-year average in Columbia River Basin above Grand Coulee Dam; 101 percent of average in the Snake River Basin above Ice Harbor Dam; 111 percent of average in the Columbia Rivers lower tributaries; 105 percent of average in the Columbia Basin above The Dalles Dam; 120 percent of average in western Washington; and 117 percent of average in western Oregon.

That contrasts with last year’s precipitation for the same period and same watersheds that were mostly in the 80 percentile range.

Snowpacks throughout the Columbia Basin are considerably higher than they were at this time last year, according to the Natural Resources Conservation Service.

As of March 2, water supply forecasts from April through September are 97 percent of average for the Columbia River at Mica Dam; 90 percent of average for the Kootenai River below Montana’s Libby Dam; 90 percent of average for the Flathead River at Hungry Horse Dam; 94 percent of average for the Spokane River; 101 percent of average for the Columbia River at Grand Coulee Dam; 94 percent of average on the Snake River at Irwin; 83 percent of average for the Snake River at American Falls; 99 percent of average for the Snake River at Lower Granite Dam; and 96 percent of average for the Clearwater River at Dworshak Dam.

The big bell weather for basin-wide streamflows is on the Columbia River at The Dalles Dam — currently projected to be at 100 percent of the 30-year average.