Avalanche Forecast

Issued: Dec 3rd, 2014 8:17AM

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.

ghelgeson, Avalanche Canada

South Rockies.

Forecast confidence is very poor, we desperately need your observations right now. Please email them to forecaster@avalanche.ca

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: Dry and cold northwest flow is giving way to rather mild southwest flow. Cold will likely remain entrenched in the valley bottoms for until Saturday when there is potential for a strong inversion. The weak flow should deliver a small amount of precip over the weekend with a healthy dose of strong SW winds. Thursday: Freezing Level: Valley Bottom; Precipitation: 0-2mm | trace-4cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SW/WFriday: Freezing Level: Valley Bottom; Precipitation: 0-1mm | trace; Wind: Treeline: Moderate, SW | Ridgetop: Strong, WSaturday: Freezing Level: 500 - 1500m; Precipitation: 0-1mm | trace; Wind: Treeline: Strong, SW | Ridgetop: Extreme, SW

Avalanche Summary

The last activity I heard tell of was an explosive trigged size 2 storm slab on a high elevation N-NE aspect. (read: old news) Seen anything more recent?

Snowpack Summary

As we begin our forecasting season, we are working with almost no field data. If you have been out in the mountains, we'd love to hear from you. There is at least one, maybe more, problematic layers in the South Rockies snowpack. Last weekends 30 - 60cm of storm snow buried a weak layer of facets over a crust which formed during November's dry spell. That interface is probably around a meter down now. Not much us known about the reactivity of this layer, nor the slab above it. But, it doesn't take much of a leap of faith to understand that a meter deep slab sitting on a persistent weak layer is a potentially bad thing.This forecast isn't going to get much better until we get some field observations. If you've got some, please send them in. Eventually you'll be able to use the Mountain Information Network, but for now please email your obs to: forecaster@avalanche.ca THANKS!

Problems

Wind Slabs

Moderate winds out of the W, NW and SW likely redistributed at least some of the weekends big snowfall into wind slabs which are probably still prone to human triggering.

Avoid freshly wind loaded features.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Be cautious as you transition into potentially wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A weak layer of facets buried a meter deep may fail when overloaded by a skier, sledder or even wind transported snow. Avalanches on this layer could be surprisingly large.

Be aware of the potential for large, deep avalanches.>Be aware of thin areas that may propogate to deeper instabilites.>Avoid convexities or areas with a thin or variable snowpack.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Valid until: Dec 4th, 2014 2:00PM