Avalanche Forecast
Issued: Dec 1st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Wind Slabs.
zryan,
Avalanche Canada
Continued precipitation overnight may create fresh wind slabs in the alpine and loose wet avalanches in the alpine and treeline. Approach avalanche terrain cautiously as we assess the impacts of several large storms.
Summary
Confidence
Weather Forecast
Wednesday overnight: 2500m freezing levels will begin to descend reaching ~1800m by morning. Another 20-40mm can be expected, initially falling as rain, and eventually falling as snow at higher elevations. Winds will continue to be strong to extreme from the southwest.
Thursday: A clearing trend! Up to 10mm of mixed precipitation can be expected in the early morning, with freezing levels sitting around 1700m. Throughout the day we will see clearing skies, gradually lowering freezing levels and winds steadily decreasing into the moderate to strong range from the west.
Friday: A brief period of high pressure prevails. A mainly sunny day with light winds from the southwest and freezing levels at valley bottom. High cloud may develop in the afternoon with another front approaching.
Saturday: Another system is upon us. 10-30cm of snow is expected throughout the day accompanied by strong westerly ridgetop winds. Freezing levels starting the day at near valley bottom rising up to 1300m.
Avalanche Summary
There have been very few reports in the past 24 hours. On Wednesday, Island Lake Lodge reported several size 1.5 wet loose avalanches out of steep alpine terrain and a Size 2 Natural Storm Slab on at NE aspect at 1900m. I suspect a widespread natural avalanche cycle has occurred in the region in conjunction with Wednesday's storm.
Reports in the region remain limited. If you go out in the mountains, please share your observations and/or photos on the Mountain Information Network!
Snowpack Summary
Heavy rain has soaked the snowpack to mountaintop in most areas. In the high alpine (above 2300m) up to 50cm of wet snow accumulation is possible. Until temperatures cool, this will result in a wet, heavy, and unstable upper snowpack.
Below 40cm of saturated storm snow lies a thick mid-November rain crust which has been the suspected bed surface of a few recent step-down avalanches. Moist snow is still found below the crust and to the ground.
Snowpack depths range from 20-50cm at treeline elevations. Expect to find a deeper snowpack at higher elevations and in previously wind-loaded areas. Snowpack decreases rapidly below 1900m.
Terrain and Travel
- The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
- Be alert to conditions that change with elevation and wind exposure.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Loose Wet
Wednesday's storm brought significant rainfall that saturated the snowpack. Cooling temperatures will help to decrease the likelihood of loose wet avalanches, but steep slopes will remain likely places for wet loose avalanches to occur - especially with a human trigger.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Heavy precipitation on Wednesday night may turn to snow up high and create a wind slab problem in the alpine. If dry snow exists in the alpine, watch out for cracking, whoomphing and wind transportation.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 2nd, 2021 4:00PM
