Avalanche Forecast

Issued: Dec 4th, 2014 7:47AM

The alpine rating is moderate, 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: A pattern shift is underway as dry and cold northwest flow gives way to rather mild southwest flow. Storm totals through the weekend look pretty bleak for the Rockies, but the door appears to be open to a succession of storms through the middle of next week.Friday: Freezing Level: Valley Bottom; Precipitation: Nil Trace; Wind: Treeline: Moderate, SW | Ridgetop: Strong, SWSaturday: Freezing Level: 500m with potential for above freezing temps between 1000m and 2000m; Precipitation: 0-1mm | trace; Wind: Treeline: Strong, SW | Ridgetop: Extreme, SW Sunday: Freezing Level: 1500m; Precipitation: 0-2mm | trace-2cm; Wind: Treeline: Moderate, SW | Ridgetop: Moderate, W/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

Wind slabs are probably getting harder to trigger on Friday. But, warm temps and big shot of SW wind on Saturday may wake them up a bit. We may even see fresh new wind slabs developing in the alpine this weekend.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

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. Forecasted warming may increase sensitivity to human triggering. Avalanches on this layer could be surprisingly large.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches.>Be prepared to back off and restrict your travel to simple terrain if you encounter above freezing temperatures.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Valid until: Dec 5th, 2014 2:00PM