Avalanche Forecast

Issued: Dec 28th, 2011 9:23AM

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

swerner, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Friday

Weather Forecast

Overnight Wednesday: Snow amounts 5-8cms. Winds 40-50km/hr from the SW. Thursday: A ridge of high pressure will likely build. This will bring dryer conditions with sunny breaks. Extreme Southerly winds expected. Friday: Light snow amounts 5-10cms. Winds will be moderate from the southwest. A light Chinook will rise freezing levels above zero in the valley.

Avalanche Summary

Some natural low density sluffing in steep, rocky terrain features. Cornice fall on N-NE aspects initiating avalanches up to size 2.

Snowpack Summary

Strong westerly winds and warmer temperatures continue forming wind slabs on lee locations. Windward aspects are being stripped, and scoured in the alpine and open treeline. A buried layer of surface hoar lies approximately 20 cm below the snow surface. This layer is not widespread; it's quite spotty through the region. This layer may be found in isolated, sheltered locations at and below treeline. The total snowpack depth around 1800m is 70cm. We're still dealing with a variable thin snowpack. Thin spot triggering down to the basal facets and depth hoar is still a concern. A well settled mid pack bridges over the basal weaknesses at the ground in thicker snowpack areas.

Problems

Wind Slabs

Wind slabs can be found on North-Southeast aspects. Cross-loading is possible on open slopes oriented parallel to the wind. You may find wind slabs further down the slope or on open wind exposed areas below treeline.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

More of an issue in the northern parts of the region where the snowpack is deeper. The mid-December surface hoar layer was destroyed in wind exposed areas. I'd be suspicious of sheltered treeline locations where it may be more preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Dec 29th, 2011 8:00AM