Colorado, Utah, Montana, and Washington ski areas saw cold temperatures last week followed by new snow, currently creating snowpack instabilities. Avalanche warnings remain at high for mountain locations in these states.
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A weak early season snowpack plagues parts of Colorado, Utah, Montana, and Washington. Recent storms deposited new snow and subsequent wind loading of many aspects, on top of faceted layers lower in the snowpack, creating high avalanche danger. Early season instabilities were marked by the death of an ice climber, December 10 in southwestern Montana, when two climbers from above triggered a wind slab that rushed down a gully the climber was ascending. Forecast centers across the west are trying to caution skiers of the weak snowpack.
The Northwest Avalanche Center report explains the volatility of the conditions, “The past week of cold weather generally created surface hoar frost, recrystallized surface snow, and faceted surface and upper snow pack layers in most areas. The last of the cooler weather systems crossed the Northwest on Sunday. This will have generally begun to build heavier new layers over hoar frost or previous weakened snow.” Similarly in Utah, Colorado, and Montana, older, weaker layers are now trying to support the weight of the new snow. In Utah, where storm totals of 48 inches occurred, avalanche forecasters are worried, advising even experts to stay within resort boundaries. Less concerned with the new snow sliding, Utah forecasters are worried about persistent slab danger with the addition of the new snow. In today’s report the Utah Avalanche Center says, “The new snow has likely gained strength, but it’s like rebuilding a nice house over a rotten foundation. It’s bound to come crashing down again.”
The Colorado Department of Transportation spent a majority of Sunday, December 13, working on the 550 corridor, a two-lane mountainous stretch of highway running through Colorado’s San Juans. Describing the avalanches, the Colorado Avalanche Information Center report says, “Recent observations told of wide spread natural activity and lots of debris across the Highway 550 corridor. Even paths that are very rare runners hit the highway in the 12 to 18 hours of intense snow and wind.” Other areas of Colorado, such as the Front Range and Summit County, also exhibit dicey conditions. The CAIC simply states, “It is a tender and reactive snowpack.”