Strong, early monsoon season predicted for western Colorado

Jason Auslander
The Aspen Times
Models from the National Weather Service's Climate Prediction Center suggest a greater chance for rain in the next three months.
Courtesy National Weather Service

While the next week to 10 days will continue to be warm and dry around Aspen, climate models indicate the upcoming monsoon season could start early and bring more rain than usual this summer, a forecaster said Wednesday.

That outlook is the opinion of experts at the Climate Prediction Center in Maryland who have come up with a precipitation outlook for the United States over the next three months, said Tom Renwick, a forecaster with the National Weather Service in Grand Junction.

Indeed, a map on the CPC website shows a green bull’s-eye hovering over the Colorado-Utah border and extending across the western half of Colorado, most of Utah, northern Arizona and the northwestern corner of New Mexico. It indicates a 40 percent to 50 percent probability of above-average precipitation for that area.

The map also indicates probable above-average precipitation for the eastern United States and Alaska, while the Pacific Northwest has a 40 percent to 50 percent chance of below-average precipitation. The rest of the West and Midwest have equal chances for below average, normal or above average rain, forecasters predict.

Renwick said that after the next 10 days or so, there’s a chance the high pressure now keeping things warm and dry in the Roaring Fork Valley and Western Slope could shift east, which would allow moisture from the Gulf of Mexico to move into the area.

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“That’s exactly what they’re thinking,” he said. “They think the monsoons might kick in earlier than usual.”

A phone message left Wednesday for a forecaster at the CPC was not returned.

Renwick, however, was careful to qualify the models as “not an exact science” and said the CPC “has been wrong and they’ve been right.”

Interestingly, the agency also has an opinion already about next winter, Renwick said, and skiers are going to like it.

A prediction released Monday indicates that last winter’s La Nina system has dissipated and that temperatures in the Pacific Ocean, which tend to control those winter conditions, have returned to “near average.” La Nina occurs when ocean temperatures cool and high pressure deflects storms north of Colorado, Renwick said.

Those Pacific Ocean temperatures are predicted to remain neutral or average through November, “with the possibility of El Nino nearing 50 percent by Northern Hemisphere winter 2018-2019,” according to a summary

El Nino occurs when ocean temperatures warm and the jet stream drops south, allowing storms to move south as well, he said.

“They’re thinking El Nino next year,” Renwick said.

Meanwhile, fire conditions in the Upper Roaring Fork Valley are not yet dry enough to merit restrictions, Parker Lathrop, Aspen Fire Protection District deputy chief, said Wednesday.

“We’re looking pretty good still,” he said, noting that fire restrictions are already in place in Mesa and Garfield counties. “(Restrictions) are creeping up in elevation, but we’re lucky because we kind of see it last.”

Fuel moisture in the upper valley remains normal, Lathrop said. If conditions remain warm and dry, fire restrictions may begin to be imposed in another 10 days to two weeks, he said. Regional fire authorities conduct a weekly conference call to review conditions, Lathrop said.

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