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Snowfall slams mountains but weakens at lower elevations

‘Southwest flow’ and banding limited accumulations
A Colorado Department of Transportation snowplow clears U.S. Highway 550 on Shalona Hill on Wednesday. Lizard Head Pass along Colorado Highway 145 and Coal Bank, Molas and Red Mountain passes on U.S. Highway 550 closed at various points as a result of severe weather conditions during two back-to-back storms that swept through Southwest Colorado from Monday afternoon to Thursday morning. (Jerry McBride/Durango Herald file)

Snowstorms forecast to hammer Southwest Colorado buried the mountains and higher elevations but missed other cities.

Durango, Hesperus and Pagosa Springs received less snow than the National Weather Service projected, while the mountains and Cortez and areas farther west approached projected snow totals. According to the Weather Service, the “southwest flow” and banding of the storm drove the discrepancies.

“It’s certainly coming in on the lower side of things,” said Mark Miller, a meteorologist with the Weather Service in Grand Junction. “We get plagued by southwest flow events where it stays milder and holds off a lot of the precipitation to the north and really hammers the San Juans. The lower elevations in the foothills tend to do a little bit worse off in those situations.”

At the beginning of the week, the Weather Service forecast significant snow totals across the region as two storms moved through back-to-back.

From Monday through Thursday, projections showed 6 to 10 inches in Cortez, 8 to 14 inches in Durango, 18 to 22 inches in Pagosa Springs and up to 2 feet in the Hesperus area.

The Weather Service issued a winter weather advisory Monday afternoon through 5 p.m. Tuesday for the cities of Cortez, Dove Creek, Mancos, Durango, Bayfield, Ignacio and Pagosa Springs calling for 3 to 6 inches of snow, and a winter storm warning from Tuesday night through 5 a.m. Thursday with an additional 5 to 10 inches of snow.

Feet of snow were forecast for the mountains over the four days. Projections showed up to 50 inches on Wolf Creek Pass and 30 to 35 inches on Red Mountain, Molas and Coal Bank passes.

Predictions largely held true in the mountains.

“The mountains did really well,” Miller said.

Snotel data collection sites in the San Juan Mountains showed 2 to 4 feet of snow in spots, and Ouray received a total of 25 inches from the two storms, he said.

Wolf Creek Ski Area reported 43 inches of fresh snow from the storm and Telluride Ski Resort on Thursday reported 30 inches of snow in the last three days.

Purgatory Resort received 45 inches over the last three days and the Durango Nordic Center near Purgatory announced 30 inches of snow in 36 hours Wednesday on Twitter.

Elsewhere, snow totals came in well below forecasts. In Durango, 5 inches of snow fell, and in Pagosa Springs, 9 inches fell – about half of projected accumulations, Miller said.

The Hesperus area received about 7 inches of snow.

Daniel Gallegos, right, and Amador Gallegos, both with Albuquerque Moving and Storage, put chains on their truck Wednesday along U.S. Highway 550 north of Durango. While lower elevations did not get much snow, travel along the Highway 550 corridor was difficult with blowing snow and limited visibility. (Jerry McBride/Durango Herald file)

Places farther to the west did better. About 11.5 inches of snow were reported near Dove Creek and 10 inches in Monticello, Utah. In Cortez, one monitoring station showed 5 inches of snowfall while another station just southeast of town collected about 9 inches, Miller said.

Again, the variability across Southwest Colorado was a result of banding and southwest flow.

Banding occurs when ribbons form within storm systems with some areas experiencing higher snowfall rates and others lighter accumulation, according to the Weather Service.

“There was some banding going on especially out west,” Miller said. “... Durango itself missed out on a lot of that banding, which hurt their totals in the long run.”

Southwest flow occurs when a storm system moves south across Nevada into Utah and then into Southwest Colorado. As the system moves, winds come from the south and southwest, bringing up warmer air. The warmer air pushes the boundaries of the storm and any snow bands farther to the north, dumping snow on the San Juan Mountains but leaving lower elevations such as Durango with less snowfall that does not stick as well.

“Colder air eventually got in to at least give some snow (to lower elevations), but certainly not as much as what we were kind of hoping for,” Miller said. “That southwest flow really keeps the storm a little bit milder for longer.”

Anticipated travel disruptions did not pan out in Durango, where roads remained mostly clear throughout both storms, but in the high country snow wreaked havoc on travel.

At various points during the storms, Lizard Head Pass along Colorado Highway 145 and Coal Bank, Molas and Red Mountain passes along U.S. Highway 550 closed as a result of severe weather conditions with blowing snow and reduced visibility.

The Colorado Department of Transportation kept all three passes along the Highway 550 mountain corridor closed Wednesday night into Thursday.

The streets Wednesday morning in Durango had little snow as accumulations veered from forecasts by the National Weather Service. (Jerry McBride/Durango Herald file)

CDOT crews repeatedly carried out avalanche mitigation on mountain passes in Southwest Colorado, but in a news release Wednesday afternoon, CDOT announced that avalanche crews had been called off mountain passes on Highway 550 for safety.

As of Thursday morning, CDOT completed avalanche mitigation on Wolf Creek Pass and U.S. Highway 160 was open.

Three crews were working on avalanche mitigation Thursday along Highway 550 and an additional crew was working on highway snow removal. Coal Bank and Molas passes reopened Thursday afternoon, but and Red Mountain Pass remained closed, according to a CDOT news release. Crews could continue working on Red Mountain Pass into Friday, the news release said.

After a dry January and early part of February, the storms were a positive development.

“The mountains really did well, which is good news for the water outlook going into the spring,” Miller said.

But the snow season is already nearing its end. Miller said snowstorms in Southwest Colorado can continue into April, but they begin to phase out at the end of March entering April – about a month away.

Southwest Colorado does not have any snow on the immediate horizon.

“The outlook isn’t great. We’re still in a La Niña pattern,” Miller said. “We’ll have to wait and see if we can get some additional snow in there, but typically as you go deeper into March and especially into April it becomes a lot less likely.”

ahannon@durangoherald.com

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