Avalanche Forecast
Issued: Dec 15th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
swerner,
Avalanche Canada
New snow and wind has built fresh and reactive storm slabs. If you see an additional 20 cm overnight bump the avalanche danger to HIGH at treeline and in the alpine.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
A series of frontal systems push inland bringing light to moderate precipitation amounts and strong southwest winds.
Tuesday Night: 10-15 cm of new snow with moderate southwest wind.
Wednesday: Snow 3-10 cm with moderate- strong southwest wind. Alpine temperatures -4 and freezing levels 1000m.
Thursday: Snow 5 cm. Alpine temperatures near -5 and freezing levels valley bottom.
Friday: Cloudy with a few sunny periods. Alpine temperatures near -7 and freezing levels valley bottom. Ridgetop winds strong from the southwest.
Avalanche Summary
On Tuesday, the recent storm snow was reactive to human triggers up to size 1.5. With continued snow and wind, storm slabs will likely remain reactive on Wednesday. Loose-dry sluffing may exist from steeper terrain features.Â
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Snowpack Summary
New storm snow accumulations from Tuesday to Wednesday afternoon are forecast 30-40 cm. This will bring 50-60 cm above the early December crust. To date, this layer has not been an avalanche concern but that concern and hazard will likely increase with additional snow/wind load. Use caution if you find cohesive snow above the crust, particularly if there are weak, sugary faceted grains immediately above the crust. Strong wind from the southwest coupled with the new snow may build new wind and reactive wind slabs above this 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
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Watch for fresh storm slabs building throughout the day.
- 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, especially where a buried crust exists. Loose-dry sluffing will likely occur from steep terrain features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 16th, 2020 4:00PM
