Avalanche Forecast

Issued: Dec 5th, 2012 10:16AM

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.

jlammers, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

Overnight and Thursday: Light snowfall / strong west winds decreasing to moderate and northwest by Thursday / Freezing level at surfaceFriday: Light snowfall / moderate to strong northwest winds / Freezing level at surface (note: models are in disagreement regarding snowfall amounts for Friday. Amounts may be closer to 15cm)Saturday: Trace amounts of snow / Light west winds / Freezing level at surface

Avalanche Summary

I expect fairly widespread windslab activity in the wake of the strong winds and snowfall on Tuesday night.

Snowpack Summary

Recent storm accumulations have been highly variable throughout the region; however, some ares have seen moderate to heavy snowfall over the past few days. In general winds have been strong creating widespread windslabs at higher elevations. Warmer temperatures and rain at lower elevations have created moist surfaces that will most likely form a temperature crust with dropping freezing levels.At the base of the snowpack you may find the early November crust which is associated with a layer of facets either directly above or below.In general, snowpack data is sparse in this region and significant variations likely exist from one drainage to another. Digging down and making your own observations will be critical to safe slope selection. Any observations from the field are welcome at forecaster@avalanche.ca.

Problems

Wind Slabs

Light to locally heavy snowfall and strong winds will have created new wind slabs and potentially add to the size and reactivity of existing storm slabs. With high wind values, loading may take place lower on the slope than normal.

The new snow may require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

We have not heard of any new releases on this early season rain crust; however, an avalanche at this interface could be surprisingly large and destructive. This layer may become reactive with increased loading.

Be alert to conditions that change with elevation.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 6th, 2012 2:00PM