21-10-27 Baldy Fall 3 Roland.jpg

An “atmospheric river” gave the central Idaho mountains—including Baldy—a taste of winter over the weekend.

South-central Idaho is on track to experience a wet winter with above-normal precipitation, bringing the region some relief from ongoing exceptional drought conditions, according to the National Oceanic and Atmospheric Administration’s long-range U.S. Winter Outlook released on Thursday morning.

That’s thanks to a “double-dip,” or second-consecutive La Niña year. The weather phenomenon, marked by cooler sea temperatures near the equator of the Pacific Ocean, tends to push the jet stream farther north and steer storm systems from the Pacific into higher-latitude states like Oregon, Idaho and Montana. (El Niño, La Niña’s counterpart, warms large areas of the Pacific and tends to push storm tracks farther south.)

To make its forecast, NOAA’s Climate Prediction Center starts a neutral forecast, featuring equal probability of above average, below average and average outcomes—33% each. From there, it shifts the probability based on what it expects to play out.

From December 2021 through February 2022, the southern half of Idaho, northern half of Oregon and western half of Wyoming is forecast to have 33-40% chance of seeing more precipitation than usual, according to the Center, a division of the National Weather Service. Residents in the Idaho Panhandle, western Montana and most of Washington, meanwhile, can expect to see a 40-50% chance of above average precipitation through February.

According to NOAA predictions, south-central Idaho and the Wood River Valley have equal chances of experiencing below-normal or above-normal temperatures. Regions in Idaho between Stanley and Wallace are 33-40% likely to see temperatures below normal; regions north of Coeur d’Alene have a 40-50% chance

“Consistent with typical La Nina conditions during winter months, we anticipate below-normal temperatures along portions of the northern tier of the U.S. while much of the South experiences above-normal temperatures,” said Jon Gottschalck, chief of NOAA’s Climate Prediction Center Operational Prediction Branch. “The Southwest will certainly remain a region of concern as we anticipate below-normal precipitation where drought conditions continue in most areas.”

As part of its annual winter outlook, NOAA also released a U.S. Drought Outlook map for November 2021 through January 2022. That map shows “persistent or worsening” severe-to-exceptional drought across the entire states of Nevada and Utah and most of Arizona, Wyoming, California and North and South Dakota. Drought improvement is predicted in Washington, Oregon, Idaho and Montana, as well as the upper Midwest and Hawaii, NOAA stated.

The agency’s Climate Prediction Center updates the three-month outlook each month; the next forecast update will be available on November 19.

NOAA’s 2021-2022 U.S. Winter Outlook map for precipitation shows that wetter-than-average conditions are favored in the Pacific Northwest and northern Rockies. With another La Niña locking in this winter, above-normal precipitation should lay down healthy snowpack in Idaho.

Email the writer: ejones@mtexpress.com

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