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Rare weather phenomenon casts strange light over Southwest Colorado

‘Pyrocumulous’ cloud collapses at wildfire, sending ash and smoke toward Durango

No, the skies above Southwest Colorado on Wednesday aren’t a sign of a coming armageddon, though given everything that’s happened in 2020, perhaps it wouldn’t be all that surprising.

Instead, the strange light over the region is the result of a unique and rare weather phenomenon set off after a series of events associated with the Pine Gulch Fire burning north of Grand Junction.

Erin Walter, a meteorologist with the National Weather Service in Grand Junction, said a storm in northeast Utah late Tuesday night brought a burst of cold air and strong wind crashing into the Pine Gulch Fire.

That collision caused what’s known as a “pyrocumulous” cloud, basically a thunderstorm driven by smoke and hot fumes from a fire, to collapse.

“When that storm collapsed, it pushed a lot of hot and dry air down into the Grand Valley, along with a lot of debris and smoke,” Walter said.

As a result, temperatures in Grand Junction spiked around midnight from 78 degrees to 90 degrees within just a few minutes, Walter said.

As ash and soot continued to fall, winds started to bring the plume south, hitting Durango with smoke and haze by late morning.

“That’s really why today has been so different and drastic,” Walter said.

Walter said the whole series of events that happened Tuesday night is not a common occurrence.

“It’s a unique event,” she said. “It was fascinating to see.”

The next few days don’t appear to offer any relief from smoke or haze. Walter said there should be an uptick in thunderstorm activity, but little chance of rain.

Four large wildfires are burning in Colorado, leading Gov. Jared Polis to enact a 30-day statewide fire ban. As of Wednesday, the Pine Gulch Fire had consumed more than 125,000 acres.

The San Juan National Forest also announced Stage 1 fire restrictions on all forest lands, effective Thursday.

A request for comment from San Juan Basin Public Health about air quality was not immediately returned Wednesday afternoon.

jromeo@durangoherald.com



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