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La Nina still augurs snow and rain, but drought returns to parts of NW

A new seasonal forecast favors above-average precipitation in Northwest, but for now drought is creeping in.
Don Jenkins

Capital Press

Published on January 23, 2018 8:25AM

Federal climate forecasters said Thursday that the rest of winter most likely will be cool and wet in the Northwest, even as other federal weather watchers reported that dry and even drought conditions have crept back into Oregon, Idaho and Washington.

The Climate Prediction Center cited La Nina’s grip on the Tropical Pacific in forecasting that the next three months will be cooler and wetter than normal in Washington, the Idaho panhandle and most of Oregon.

Meanwhile, the U.S. Drought Monitor, produced by a separate agency, released a weekly update that showed parts of the Northwest was drying out, most notably in Oregon.

Some 11 percent of the state, spread across parts of 10 Eastern Oregon counties, is in a “moderate drought,” the lowest classification. It’s the first official sign of drought in Oregon since October. The swath of drought extends slightly into Idaho, taking in a little more than 1 percent of that state.

The new three-month outlook is similar to previous seasonal forecasts. La Nina, a cooling of ocean surface temperatures along the equator, generally brings below-average temperatures and above-normal precipitation to the northern U.S.

A weak to moderate La Nina formed last fall. Although this La Nina’s strength may have peaked, the ocean almost certainly won’t warm to normal temperatures until the spring, according to the National Oceanic and Atmospheric Administration.

La Nina has yet to produce large amounts of snow in the mountains.

Oregon snowpacks are well below normal for mid-January, according to the Natural Resources Conservation Service. Snowpacks in 11 basins monitored daily by NRCS ranged Thursday from a high of 56 percent in northeast Oregon to a low of 23 percent in the Klamath Basin in Southern Oregon.

Snowpacks in Washington, Idaho and Northern California are generally better, though some basins are well below normal.

A basin that feeds the Lower Columbia in southwest Washington was 65 percent of normal on Thursday, according to NRCS. The Owyhee Basin in the southwest corner of Idaho was at 37 percent. Snowpacks in Northern California basins were 65 percent or higher.

The percentage of Oregon that is abnormally dry increased to 65 percent from 22 percent the week before, according to the Drought Monitor.

Portions of southwest and south-central Washington, making up 9 percent of the state, are abnormally dry.


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