Avalanche Forecast

Issued: Dec 5th, 2012 3:00PM

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

mike.koppang, Alberta Parks

Kananaskis.

LOTS of new snow is available for transport and winds have been moderate to strong out of the SW over the past few days! Avoid open wind affected terrain right now. Things are improving but we are still in a very touchy period.

Summary

Confidence

Fair - Wind speed or direction are uncertain on Thursday

Weather Forecast

Snowfalls are expected to diminish on Friday with only a few cms of new snow expected overnight. The Moderate to strong SW winds will continue overnight and then begin to ease on Thursday morning. Tempertures are beginning to become more seasonal with -13C forecast for 3000m.

Avalanche Summary

Numerous loose dry avalanches up to sz 1.5 were observed throughout the forecast region. Upper snowpack is sluffing easily with skier traffic. A suprising lack of slab avalanche activity was observed. Also, we recieved a 3rd hand report of a skier accidental avalanche in the area surrounding Murray Moraines. The slide was a sz2 with one person partially buried loosing some gear. Details are sketchy and we have not had the stability to investigate the area.

Snowpack Summary

20-25cm new snow overnight by Wednesday morning with moderate to strong SW winds at treeline elevations and above. Pockets of wind slabs are being encountered in the upper snowpack up to 40cm thick that are reactive to ski cutting in steeper unsupported features. Midpack is well settled with the 1106CR down 100cm on average throughout the forecast region. Hard results are being encountered underneath the crust in a layer of FC sz 203.

Problems

Storm Slabs

20cm of new snow overnight along with moderate to strong SW winds are creating widespread storm slabs in alpine areas and isolated windslabs at treeline. Recent storm snow total are close to 50cm so lots of snow is currently available for transport.

Assess start zones carefully and use safe travel techniques.>Avoid freshly wind loaded features.>Travel on ridgetops to avoid wind slabs on slopes below.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Loose Dry

Loose dry avalanches from steep unskiable terrain on all aspects, but more prominent on lee aspects.

Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 4

Persistent Slabs

The Nov rain crust persists about 30+cm off the ground throughout the forecast area and is reactive to stability tests in the hard range. Avalanches in the upper snowpack may step down to this weakness.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be aware of thin areas that may propagate to deeper instabilites.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

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