Avalanche Forecast

Issued: Feb 22nd, 2013 8:29AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Cornices.

Avalanche Canada pmarshall, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: There is a brief break between weather systems on Saturday before the next frontal system arrives late Saturday and into Sunday.  Saturday: Cloudy with light snow and possible sunny breaks. The freezing level is around 400 m and winds ease to moderate from the southwest. Sunday: Moderate snowfall – 10-20 cm. The freezing level is around 500 m and winds are moderate to strong from the southwest.Monday: Cloudy but drier. The freezing level remains around 500 m and winds are light from the southwest.

Avalanche Summary

A natural avalanche cycle was likely on Friday in response to heavy snow and strong winds. Observations from Thursday were limited due to poor weather, but there were a few reports of easily triggered slab avalanches up to size 1.5 failing within the storm snow. Most of these slides were from below treeline elevations.

Snowpack Summary

30-60 cm of new snow had fallen by Friday morning, accompanied by strong southwest winds. Deep and dense wind slabs have formed in exposed lee terrain. This new snow fell on a crust, old wind slab, and/or surface hoar depending on aspect and elevation, and may not bond well initially. Cornices that now loom over many features may become weak with continued growth and/or daytime warming. The mid and lower snowpack layers are generally well settled and strong.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow may not bond well to the previous snow surface (surface hoar, wind slab, crust) and may be easily triggered by additional loading. Be especially wary of exposed north through east facing slopes where wind loading is likely.
The new snow will require several days to settle and stabilize.>Avoid lee and cross-loaded terrain near ridge crests.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 6

Cornices

An icon showing Cornices
The recent snow and wind have been building cornices on lee features. These cornices are likely weak and may fail at anytime. Cornice failure has the potential to trigger large avalanches.
Give cornices a wide berth when travelling on or below ridges.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Feb 23rd, 2013 2:00PM