Avalanche Forecast

Issued: Nov 30th, 2013 8:20AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs and Persistent Slabs.

Avalanche Canada triley, Avalanche Canada

Avalanche danger is increasing with the added load of new storm snow. The cooling trend with this storm is expected to bring enough snow to below treeline elevations to produce avalanches.

Summary

Confidence

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

Weather Forecast

Overnight and Sunday: Moderate to locally heavy precipitation overnight as the arctic front collides with Pacific moisture. Expect strong westerly winds ahead of the arctic air, and moderate northerly winds after the passage of the cold front.Monday: Precipitation should end during the day. Expect clearing skies and cold valley temperatures.Tuesday: Clear and cold with moderate Northeast winds.

Avalanche Summary

We have received no new reports of avalanche activity, but observations have been limited. Avalanche activity is expected to increase throughout the weekend with forecast snow and wind. If you have been out in the mountains and observed recent avalanche activity, please report it to forecaster@avalanche.ca

Snowpack Summary

Snow depth is typically 80-110cm at treeline with 60 to 70cm of well settled snow sitting on the October crust located just above the ground. Little is known about the bond to this crust; however, limited reports suggest that it is currently well bonded. The snow surface on sun exposed alpine slopes, and all slopes below treeline, has been subject to daily melt-freeze cycles. Large surface hoar has also formed on all aspects. Although it has been melting on south aspects during the day, it has likely been regrowing overnight. If you are traveling in the mountains, now is a good time to make note of these surface conditions which may become persistent weak layers once buried by a sufficiently cohesive slab.

Problems

Storm Slabs

An icon showing Storm Slabs
The forecast new snow and wind is expected to develop storm slabs. These storm slabs may not bond well to buried weak layers.
The new snow will require several days to settle and stabilize.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Areas that have a deeply buried early season crust may become reactive due to the increased load from the storm snow.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Dec 1st, 2013 2:00PM