Backcountry travelers warned about high avalanche danger
Backcountry travelers were warned by the Colorado Avalanche Information Center (CAIC) to be extremely careful this week in the Aspen area after a storm dumped up to four feet of wet, heavy snow in the mountains by Tuesday morning.
CAIC forecaster Brian McCall upgraded an avalanche watch to a warning on Tuesday. He said a high danger of slides over a widespread area warranted the upgrade. He said the avalanche danger was nearly certain to remain high at least through Wednesday.
“Mild temperatures are creating an unstable snowpack where dense snow rests on top of lighter snow,” McCall wrote on the CAIC website. “Natural and human-triggered slides are likely across the warning area. Backcountry travelers should stay well clear of any avalanche terrain.”
The avalanche rating in the Aspen zone was “high,” or a four on a scale of one through five. McCall said Tuesday he tried to emphasize in his forecast that anyone considering backcountry travel must be careful.
“Hopefully there’s enough on the website to get their attention,” he said.
The latest storm cycle, which started last Wednesday, dumped a high volume of snow above 9,000 feet. Warm temperatures have created an unusually high moisture content in the snow.
New snowfall exceeded four feet in the upper Crystal River Valley by Tuesday morning, McCall said. The snowpack on Schofield Pass increased from 80 percent of normal to 133 percent of normal in just a week.
Persistent winds out of the southwest have transported the new snow to form slabs on easterly aspects of peaks.
The slide danger has skyrocketed because the heavy, wet new snow is resting on weak layers of old snow. The stress creates the risk of large avalanches transporting all the snow that has accumulated.
“We could see them running full track,” McCall said, explaining that all the snow from the start of an avalanche to the valley floors could run.
“Natural and triggered avalanches are occurring in the backcountry,” CAIC’s forecast said. “Some of these avalanches will be large and destructive, running far down their tracks towards the valley bottoms.”
Forecasters advised avoiding travel on or below any steep terrain on Tuesday. Anyone venturing into the backcountry was advised to stick to low-angled slopes out of range of avalanche run-out paths.
Several avalanches in the Aspen area were reported to the CAIC’s Aspen office Monday. A “large and destructive” natural avalanche was observed in Maroon Bowl from Highland Ridge. Observers in the Marble area saw natural activity on north through east aspects near treeline. A backcountry group on Monday evening saw an avalanche 75 yards wide pile up 18 inches of debris on the road to the Tagert Hut in the Castle Creek Valley.
Aspen’s ski areas received nine to 12 inches of snow in a 24-hour period as of Tuesday morning. There was a steady boom of dynamite charges at Aspen Highlands and Snowmass at around 8 a.m. as the patrol triggered slides on some of the in-bounds terrain.
There hasn’t been good visibility since last weekend, so McCall said the CAIC hasn’t been able to gauge how many avalanches have occurred in the backcountry.
The avalanche warning was extended Tuesday in the southern San Juan and Gunnison zones. The Grand Mesa and Steamboat zones as well as Aspen were added to the avalanche warning.
CAIC said the weather “looks to fully dry out by Christmas.”
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