La Niña to keep Colorado drier and warmer than normal
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National Weather Service

While smoke darkens Front Range skies and the Gunnison Valley turns to shades of brown, it may be hard to believe that it’s getting deep somewhere in the Western U.S. But the mountains of Western Montana have already received feet of snow, and more is forecast for the region this week.

It is part of a pattern that the National Weather Service predicts will continue all winter: ample snow in the Northern Rockies and worsening drought in Colorado.

If the forecast holds true, the effects would be “exponential” for Gunnison Valley ranchers already hard hit by a dry summer that reduced hay production and rangeland forage by 30%, said Dan Olson with the Natural Resource Conservation Service field office in Gunnison.

“One year of this drought is crippling,” Olson said. It would be “a real challenge if we had multiple years like this one.”

The weather service issued its winter outlook for the U.S. on Oct. 15 and pinned many of its predictions for the western part of the country on the continuation of a La Niña, a band of cooler-than-normal sea surface temperatures in the Central Pacific. Those cool waters began showing up on satellite images in August, and the service forecasts the pattern to continue through the winter.

La Niña years favor precipitation and cooler temperatures in the Northern U.S. Winter storms from the southwest, which tend to dump snow on the San Juans and can produce powder days in Gunnison County, are less likely to occur during La Niña. This is linked to the Pacific Jet Stream staying north of the Southwest U.S. during La Niña winters.

This jet stream pattern has been in effect for most of October, and is a main reason why Colorado has stayed mostly dry and Montana has been consistently snowy this fall.

The weather service splits Colorado in half with regards to its winter precipitation predictions. The northern half of the state is forecast to have equal chances of above-average or below-average snowfall. The southern portion of the state, however, is favored to have drier-than-average weather. Gunnison County sits on the dividing line.

Worsening drought and warmer-than-average temperatures are predicted for all of Colorado this winter. Drought in Wyoming, Utah, New Mexico, Arizona, Nevada, California and Texas will continue, worsen or develop, according to the winter outlook.

Blue Mesa Reservoir did not fill to capacity this summer, and unregulated flows into the reservoir were 64 percent of average this year. The water level in Blue Mesa dropped to 50% of capacity this month. The major water sources for the reservoir — the Gunnison River and the Lake Fork of the Gunnison — were flowing at about 53% of average as of Monday.

Sonja Chavez, general manager of the Upper Gunnison River Water Conservancy District said the dry outlook means ranchers will have conversations with their neighbors on how to share water, and recreationists will be planning on another short river season.

“If the drought persists, our reservoirs will not fill. We'll need another ‘Miracle May’ like that of 2019 and/or a snowpack well above average to save us from what looks to be a very tough year in 2021,” Chavez said.

 

(Sam Liebl can be contacted at 970.641.1414 or editor@gunnisontimes.com)