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Avalanche Forecast

Archived

Dec 24th, 2019–Dec 25th, 2019

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

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Happy Holidays! While taking your new toys out in the mountains, keep in mind that avalanches are possible to trigger at middle and upper elevations, where the snow is drier and deeper. In the Crystal region, very large and destructive avalanches have been observed and require an added layer of caution.

Discussion

The snowpack and resulting avalanche hazard change by location and elevation around the West South region. You may experience locally lower avalanche danger in areas that did not receive the massive water numbers of Crystal and Paradise (7.45” and 6.57” respectively). Throughout the zone, wind loading and newly formed cornices have been reported. Look for evidence of recent avalanches, whumpfing, and shooting cracks as red flag indicators of instability. At lower elevations, there just isn’t enough soft snow to form an avalanche hazard. Instead, expect difficult travel conditions with refreezing snow, exposed objects, and open creeks. 

In the Crystal area, reports of recent large avalanches continue to be reported, letting us know that instability is clearly present. 

One example of the many natural avalanches from the storm Jeremy Allyn observed on Tuesday in the Lakes Basin area of Crystal. Photo: Jeremy Allyn 12/24/19

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

 

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.