Avalanche Forecast

Issued: Jan 18th, 2013 4:32PM

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

A.L. Horton, Parks Canada

Jasper.

The declining avalanche danger ratings depend on the cooler temperatures in this weekend's weather forecast. Danger ratings will rise on Monday with predicted rain and warming temperatures.

Summary

Weather Forecast

Temperatures will begin a slight cool down on Saturday. Moderate to strong ridge top winds will continue. Light precipitation can be expected with broken skies.

Snowpack Summary

Extreme NW winds have stripped alpine and tree line fetch zones. Hard to soft wind slabs are present on all lee slopes, predominately tree line and above. In thin areas, these slabs are sitting on weak basal facets. Below tree line, the old storm snow is moist and will consolidate with cooling temperatures, over a rotten base of facets.

Avalanche Summary

In the area around Whistler's, numerous full depth natural slab avalanches have been observed on thin, steep, lee slopes in the alpine. We are seeing wide propagation to size 3 from continued NW wind loading. These avalanches are running far in paths with steep run outs.

Confidence

Freezing levels are uncertain on Saturday

Problems

Wind Slabs

Hard to soft wind slabs have developed on lee aspects. Numerous full depth natural slab avalanches have been observed on thin, steep, lee slopes in the alpine. Wide propagations can be expected.

Carefully evaluate and use caution around thin snowpack areas.Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Wind slab avalanches primarily in the alpine, have triggered this weakness. These avalanches have gained significant mass as a result. This situation will more likely occur in shallow snowpack areas.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Valid until: Jan 19th, 2013 4:00PM