Avalanche Forecast
Issued: Dec 19th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
jcoulter,
Avalanche Canada
New snow, strong wind and rising freezing levels will combine to make dangerous avalanche conditions. Staying out of avalanche terrain and away from overhead hazards is recommended.
Summary
Confidence
Weather Forecast
SATURDAY NIGHT - Snow, heavy at times 12-25 cm / southwest wind moderate, gusting to strong / alpine low temperature near -2 / freezing level 1200-1500 m
SUNDAY - Chance of flurries with sunny breaks / gusty southwest winds / alpine high temperature near 0 / freezing level 2000 m
MONDAY - Snow/Rain 10-20 cm / southwest wind, 30-40 km/h gusting to 85 km/h / alpine high temperature near 0 / freezing level up to 1700 m
TUESDAY - Periods of of snow, possibly heavy at times / moderate east winds / freezing levels initially high, but dropping at tail end of storm
Avalanche Summary
On Saturday explosives produced results up to size 2 on the early December crust. On Friday there were a few natural size 2 wind slab avalanches reported in the alpine.
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Snowpack Summary
Strong wind from the southwest and fresh snow has likely formed new reactive storm slabs. Depending on aspect and elevation 60-100 cm now sits on the early December crust. This crust may have persistent weak, and facetted crystals above and below it.
Deeper in the snowpack are two hard melt-freeze crusts that formed in November that may have some weak crystals around them. There is uncertainty if and where in the region this may be a problem. Without any recent avalanche activity, it appears that this layer is dormant for the time being.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Don't let the desire for deep powder pull you into high consequence terrain.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
New storm snow has likely formed reactive slabs. Strong southwest wind will create deeper slabs on leeward slopes that could produce larger avalanches. Avalanches may entrain moist snow if the runouts extend into below treeline elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Depending on elevation and aspect, 50-100 cm of snow currently sits above a buried crust from early December. Sugary, facets above and/or below the crust may weaken the bond and the persistent slab may become reactive, especially to human triggers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 20th, 2020 4:00PM
