Avalanche Forecast

Issued: Nov 23rd, 2015 8:00AM

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

chris gooliaff, Parks Canada

Glacier.

Today is the start of the Winter Permit System. A valid winter permit is required to enter Winter Restricted Areas. Know before you go!

Summary

Weather Forecast

A brief storm is rolling through the region today, bringing 15-20cm of snow, with freezing levels remaining in the valley bottom and moderate SW winds at ridge top. By Tuesday afternoon, cold Arctic air will have slid into the Columbia's, bringing northerly winds, clear skies, and cold temp's. The Arctic air will stick around for few days.

Snowpack Summary

Recent observations suggest that the ~1m of storm snow is settling and bonding. Surface hoar layers down ~1m and 1.5m are still a concern but becoming more stubborn and hard to find. On high elevation N/NE aspects, there is a weak facetted base.

Avalanche Summary

Several large (size 3) avalanches were observed on Rogers Peak, Swiss Peak, and Hermit Mtn. They appear to be deep releases (80-100cm), but the crowns were filled in slightly, so the exact timing of their release is possibly Saturday. Isolated soft slabs to size 2 were observed from steep, north-facing terrain on Mt MacDonald yesterday.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Strong SW winds in the last 24 hours have transported the recent storm snow and created wind slabs and significant loading in lee areas. Extra caution should be used when transitioning into wind affected terrain.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Deep Persistent Slabs

On northerly alpine slopes, snow from early Sept was preserved and facetted forming a basal weakness. This may have been the failure plane on Swiss and Hermit Peak on the weekend.

Avoid shallow snowpack areas where triggering is more likely.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

3 - 4

Valid until: Nov 24th, 2015 8:00AM