Avalanche Forecast

Issued: Dec 2nd, 2011 8:22AM

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

pmarshall, Avalanche Canada

Sea To Sky.

The current snowpack requires discipline and conservative terrain choices. Large avalanches are still possible.

Summary

Confidence

Fair - -1

Weather Forecast

A strong ridge of high pressure persists through Monday bringing a mix of sun and cloud, light-moderate N-NW winds, and daytime freezing levels as high as 2500m.

Avalanche Summary

Avalanche activity has tapered off in the past couple days. Although the likelihood of triggering avalanches is lower, the potential consequences are still very high.

Snowpack Summary

We are dealing with a complex and somewhat unusual snowpack for the South Coast. Around Whistler there are several different persistent weak layer deep in the snowpack including a layer of depth hoar right near the base of the snowpack and at least two distinct crust/facet combinations between 50-100cm above the ground. Recent storms have dumped up to 200cm of snow on top of the weak underlying snowpack. All this new snow is making it less likely to trigger the deeper weaknesses, but if you do hit the sweet spot the resulting avalanche could have very serious consequences. The greatest concern is with complex, rocky slopes above 1900m that have not recently avalanched.

Problems

Wind Slabs

Gusty N-NW winds have formed stiff or hard wind slabs on south through east facing terrain (reverse loading pattern). Old buried wind slabs are still lurking on exposed northerly aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

Be particularly cautious in shallow or variable snowpack areas and on slopes that did not recently release. I'm thinking rocky alpine start zones and slopes that vary from thick pillows of snow to thin wind scoured areas in a short distance.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Dec 3rd, 2011 8:00AM