Avalanche Forecast
Issued: Dec 16th, 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.
swerner,
Avalanche Canada
Storm slabs are likely reaching threshold and reactive to human triggers. Choose conservative terrain and watch for signs of instability such as whumphing, cracking and recent avalanches.
Summary
Confidence
Weather Forecast
Wednesday Night: Snow amounts 10-15 cm with ridgetop wind strong from the southwest. Freezing levels 1000 m.
Thursday: Cloudy with some sunny periods. Snow amounts 5-10 cm through the day. Freezing levels 1200 m and ridgetop wind strong from the southwest.
Friday: Light to moderate snow amounts developing through the day and overnight. Moderate gusting strong southwest wind.
Saturday: Light snow through the day with more snow and rising freezing levels to 1400 m overnight.
Avalanche Summary
On Wednesday, numerous avalanches were seen in the alpine up to size 2. With continued snow and wind, storm slabs and persistent slabs will likely remain reactive on Wednesday. Loose-dry sluffing may exist from steeper terrain features.
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Snowpack Summary
Strong wind from the southwest coupled with the new snow will likely build reactive storm slabs. The recent storm snow accumulations bring 40-60 cm above the early December crust. To date, this layer has not been an avalanche concern but by Thursday it may reach its tipping point and that concern and hazard will likely increase with snow/wind load and rising freezing levels. Use caution if you find cohesive snow above the crust, particularly if there are weak, sugary faceted grains immediately above or below the crust.
Deeper in the snowpack are two hard melt-freeze crusts that formed in November. The concern would be if there were weak faceted grains around the crust, but 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.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Avoid areas where the snow feels stiff and/or slabby.
Problems
Storm Slabs
The new storm snow is building reactive storm slabs. Strong southwest wind is forming deeper slabs on leeward slopes that could produce larger avalanches. Loose-dry sluffing will likely occur from steep terrain features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
40-60 cm of snow currently sits above a buried crust from early December. A cohesive slab will likely exist with forecast snow, strong wind, and warming. 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: All elevations.
Likelihood
Expected Size
Valid until: Dec 17th, 2020 4:00PM
