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 Storm Slabs and Wet Slabs.
TRettie,
Avalanche Canada
A large, widespread natural avalanche cycle will begin tonight and continue into Wednesday. Avoid all avalanche terrain.
Summary
Confidence
Weather Forecast
Tuesday night: Another warm wet storm will hit the range tonight. Freezing levels will rise to 1600m with up to 20mm of precipitation and strong winds from the Southwest.
Wednesday: Freezing levels will remain around 1600m for the day. Moderate to heavy precipitation with the highest amounts expected in the South of the range. Up to 50mm. Winds will continue to be strong from the Southwest.
Thursday: A weak ridge of high pressure will build over the range bringing dry conditions. Freezing levels will fall to valley bottom or near valley bottom. Alpine winds will be moderate from the West.
Friday: -10 at 1500m, no precipitation expected and alpine winds light from the West.
Avalanche Summary
A consistent storm pattern has given the snowpack little time to stabilize between snowfalls. Heavy snowfall, strong winds, and rising freezing levels will layer increasingly large and reactive storm slabs across the region over the coming days. Both the new snow interface and other recent (deeper) storm interfaces have potential to act as failure planes in forecast avalanche activity.
Several wet slab avalanches up to size 2.5 were observed on Monday. We expect to see more of these type of avalanches in the treeline and below treeline as freezing levels once again rise and rain is expected at lower elevations.
Snowpack Summary
The incoming storm will form touchy storm slabs in the treeline and alpine. Large and destructive avalanches are expected.
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The mid and lower snowpack contains multiple crusts that seem to be holding strong. Forecast snowfall and associated natural avalanche activity will test them.
Snowpack depths are currently around 100 cm below treeline, but shrink rapidly below 1600 m. Alpine snowpacks are expected to be around 150 cm deep, but could be 230 cm or more in areas with more snowfall or wind-transported snow. The deepest snowpacks this season have been reported near Blue River and Valemount.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
- Keep in mind that wet avalanches can be destructive due to their high density.
Problems
Storm Slabs
Yet another powerful storm will bring moderate to heavy snowfall to the region along with strong winds and rising freezing levels. Storm slabs and wind slabs will grow in size and in sensitivity to triggering.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wet Slabs
As the storm progresses and falling precipitation turns from snow to rain wet slab avalanches can be expected at lower elevations.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 1st, 2021 4:00PM
