Avalanche Forecast
Issued: Dec 21st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
mconlan,
Avalanche Canada
Snow, rain, and wind will hammer the region Monday night. Buried weak layers will need time to equilibrate to this substantial load. Travel in avalanche terrain is not recommended until we have evidence of a stabilizing snowpack.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Snow, accumulation 20 to 40 cm with the most in the west of the region, 40 to 80 km/h west wind, alpine temperature -1 C, freezing level 1800 m.
TUESDAY: Mix of sun and cloud, 40 km/h north wind, alpine temperature -10 C.
WEDNESDAY: Clear skies, 10 to 20 km/h west wind, alpine temperature -8 C.
THURSDAY: Clear skies, 20 km/h southwest wind, alpine temperature -2 C.
Avalanche Summary
It is anticipated that a natural avalanche cycle occurred during the storm on Monday night. Photos in this MIN show a close-up of how dangerous the snowpack is right now. Expect human-triggered avalanches to be very likely to occur on Tuesday as the snowpack equilibrates to the new load.
Snowpack Summary
A hefty storm impacted the region Monday and Monday night, with around 30 to 40 cm of snow accumulation expected by Tuesday morning. Some of the snow may fall as rain below 1800 m. Strong wind during the storm started from the south, shifted to the west, and finally to the north. Expect to find reactive storm and wind slabs across the region. The snow will likely take a few days to bond to the snowpack.
This snow is loading weak layers around 50 to 100 cm deep. The layers may be composed of feathery surface hoar and/or sugary faceted grains and they overly a hard melt-freeze crust. There has already been substantial avalanche activity on this layer from natural and human triggers. This layer remains a major concern, as humans may be able to trigger large and destructive avalanches on it.
Another crust with associated faceted grains may be found near the base of the snowpack. There have been no recent avalanches reported on this layer but it remains on our radar. The most likely place to trigger it would be from shallow, rocky terrain.
Terrain and Travel
- Travel in alpine terrain is not recommended.
- Be careful to keep storm day fever from luring you out into bigger terrain features.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Problems
Persistent Slabs
Weak layers of surface hoar and/or faceted grains overly a hard melt-freeze crust around 50 to 100 cm deep. The layers likely went through a natural avalanche cycle during Monday's storm. The likelihood of triggering these layers will remain very likely on Tuesday as it stabilizes with the load that was added to it.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
We are expecting to wake up to snow accumulations of around 30 to 40 cm by Tuesday morning. Strong wind from variable directions may produce even deeper pockets. This snow will be reactive to riders and need time to bond to the snowpack. Don't let good visibility lure you into dangerous avalanche terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 22nd, 2020 4:00PM
