Avalanche Forecast
Issued: Nov 30th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Storm Slabs.
cgarritty,
Avalanche Canada
Heavy rain followed by alpine snowfall is Wednesday's recipe for rapidly changing and dangerous avalanche conditions.
Summary
Confidence
Weather Forecast
Tuesday night: Heavy rain; 30-40mm. Strong to extreme south or southwest winds.
Wednesday: Heavy rain; 40 mm accumulation. Strong south or southwest winds. Treeline high temperatures around +4.
Thursday: Mainly sunny. Light variable winds. Treeline temperatures of -1 to -4, dropping over the day.
Friday: Mainly sunny, clouding over in the afternoon. Light variable winds. Treeline high temperatures around -1.
Avalanche Summary
Wednesday's forecast suggests we may see another day of rapidly evolving avalanche conditions. If daytime freezing levels fall low enough we could see substantial storm slabs form in the region's upper elevations before the end of the day, particularly in alpine areas. A rapid transition from active wet loose avalanche conditions to a touchier new storm slab problem should be on your mind as new snow begins to accumulate.
Snowpack Summary
Heavy rain has affected the snowpack at all elevations. Significant new snow (15-30 cm) may accumulate at high elevations during the final hours of the storm on Wednesday. This could set up a scenario where unstable new storm slabs become a serious concern before the end of the day.
Average treeline snow depths are around 80-100 cm with much of treeline and all but the uppermost below treeline elevations still below threshold depths for avalanches.
Terrain and Travel
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- Keep in mind that wet avalanches can be destructive due to their high density.
- Dial back your terrain choices if you are seeing more than 20 cm of new snow.
Problems
Loose Wet
Wednesday will be the second day of heavy rain saturating the snowpack. Steep slopes will remain likely places for wet loose avalanches to occur - especially with a human trigger.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
Forecast weather suggests a substantial storm slab problem could form as rain switches to snowfall on Wednesday, particularly in the alpine. The greater the new snow accumulation, the more serious this problem will be.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 1st, 2021 4:00PM
