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Avalanche Forecast

Archived

Nov 20th, 2012–Nov 21st, 2012

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

Regions

Glacier.

The winter permit system is NOT yet in effect but is scheduled to come into effect on Friday November 23. Click here for information on how to obtain annual and daily winter permits. 

Weather Forecast

Continued southwesterly flow will bring mild temps, moderate to heavy precipiation, and moderate to strong southwesterly winds. The system is tracking slightly south of Rogers Pass; areas south of the highway will likely get more new snow.

Snowpack Summary

24cm of snow is adding to the load on the Nov 6 crust, down 60-80cm. It appears to be more reactive in the Asulkan Drainage where tests are easy sudden planar.  A cohesive storm slab has formed and is reactive where is overlies the Nov 16 sun crust down 40.

Avalanche Summary

Recent avalanche activity has been linked to spikes in wind speeds at ridgetop, loading lee slopes. This mornings avalanche patrol observed 6 size 3 and 4 size 2.5 slab avalanches from steep north and south facing slopes, running into fans.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.