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 Wind Slabs.
swerner,
Avalanche Canada
There is a lot of recent snow available for transport and a lot of wind in the forecast. A bit of new snow, accompanied by strong southwest winds will likely build reactive wind slabs at treeline and in the alpine on Wednesday. Use as conservative approach to terrain selection.
Summary
Confidence
Low - Uncertainty is due to the track & intensity of the incoming weather system. Uncertainty is due to limitations in the field data.
Weather Forecast
A series of frontal systems push inland bringing light precipitation amounts and strong southwest wind.
Tuesday Night: Trace of new snow with strong southwest wind.
Wednesday: Trace of new snow and strong southwest wind. Alpine temperatures -6 and freezing levels valley bottom.
Thursday: Snow 10-15 cm and strong southwest wind continue. Alpine temperatures near -5 and freezing levels valley bottom.
Friday: Cloudy with a few sunny periods. Snow 5 cm. Alpine temperatures near -7 and freezing levels valley bottom. Ridgetop wind strong from the southwest.
Avalanche Summary
No new avalanches reported on Tuesday.
Small (size 1 to 1.5) wind slab avalanches were observed out of steep terrain on Sunday and Monday, being triggered naturally and by riders.
Please consider sharing your observations on the Mountain Information Network. Thank you to those that have already submitted this winter.
Snowpack Summary
Up to 30 cm of snow from last week overlies a hard melt-freeze crust formed in early December at least up to 2000 m. To date, this layer has not been an avalanche concern but use caution if you find cohesive snow above the crust, particularly if there are weak, sugary faceted grains or feathery surface hoar crystals above the crust. Strong wind from the southwest is forecast for the rest of the week along with a bit of new snow, which may form new wind slabs above this crust.
The snowpack depth varies substantially in the region and has been described as thin, wind-hammered, variable, and tapering rapidly at lower elevations. The average snowpack depth at treeline is approximately 100 cm.
The middle of the snowpack has been reported as being well-consolidated and may host another hard melt-freeze crust.
The base of the snowpack consists of a hard melt-freeze crust from early-November that may have faceted grains around it. There has not been recent avalanche activity on this layer but it remains on our radar. The most likely spot to trigger it would be on thin and rocky slopes.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Avoid areas where the snow feels stiff and/or slabby.
Problems
Wind Slabs
Strong southwest wind is forecast for the rest of the week along with a bit of new snow. Use caution near ridges and avoid leeward slopes, particularly where you find stiff wind affected snow. Loose-dry sluffing from steep terrain features.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 16th, 2020 4:00PM
