Avalanche Forecast

Issued: Nov 24th, 2012 9:49AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Storm Slabs and Persistent Slabs.

Avalanche Canada jlammers, Avalanche Canada

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the forecasters blog for further details on interpreting early season bulletins.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Sunday: A few clouds with the possibility of light flurries / Light to moderate northwest winds / Freezing level at 800mMonday: Mainly sunny / Light to moderate northwest winds / Freezing level at 900mTuesday: Mainly sunny / Light to moderate northwest winds / Freezing level at 1200m

Avalanche Summary

Just before the weekend we received a report from the Valemount area of  a snowmobile triggering a size 2.0 avalanche that was about 70 cm deep and about 80 metres wide. The avalanche was triggered from a shallow weak area, and suspect that the weak layer was either the November crust or buried surface hoar. Please send us an email if you have any observations.

Snowpack Summary

Snow accumulations from Friday were highly variable in the region with some areas receiving over 30cms over the 24hr period. Although alpine wind data has been sparse, velocities in neighboring regions have been in the upper end of moderate. That said, I'd be highly curious about the possibility of windslabs in exposed areas. The recent snowfall adds to the healthy amounts that have fallen over the past few days. There may be a thin buried surface hoar layer down about 85 cm in the alpine. As well, the November rain crust now exists over 100cm down in some locations and may exist in combination with facets. Buried persistent weak layers may become reactive with the recent storm loading.

Problems

Storm Slabs

An icon showing Storm Slabs
Moderate accumulations have added to a building storm slab problem that most likely exists as a wind slab in exposed areas. Although storm slabs should strengthen over the next few days, an avalanche may trigger deeper persistent weaknesses.
Be cautious as you transition into wind affected terrain.>If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
There is a variable crust that exists in the lower snowpack. Watch for triggering on unsupported terrain at higher elevations or within start zones with smooth ground cover (scree fields, glacier headwalls, slopes with snow from last year).
Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Nov 25th, 2012 2:00PM