Avalanche Forecast
Issued: Dec 18th, 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.
kdevine,
Avalanche Canada
The recent snow has added load to buried weak layers and may still be reactive to human triggers, especially in wind loaded areas. Conservative terrain selection is recommended.
Summary
Confidence
Weather Forecast
FRIDAY NIGHT - Mainly cloudy with flurries, 5-15 cm / southwest wind, 50-80 km/h, gusting to 100 km/h / alpine low temperature near -4 / freezing level 1100 m
SATURDAY - Mainly cloudy with scattered flurries, and 10-20 cm of snow on Saturday night / southwest wind, 40-80 km/h / alpine high temperature near -2 / freezing level 1500 m
SUNDAY - A mix of sun and cloud / southwest wind, 30-60 km/h / alpine high temperature near 0 / freezing level 2000 m
MONDAY - Flurries, 10-15 cm / southwest wind, 30-40 km/h gusting to 85 km/h / alpine high temperature near 0 / freezing level 2000 m
Avalanche Summary
On Friday there were a few natural size 2 wind slab avalanches reported in the alpine.
On Thursday, a natural size 2 storm slab from NE alpine terrain was reported. As per the report, this slab likely failed on Wednesday. On Thursday, explosives were able to trigger slabs up to size 2 in the alpine and a size 1.5 at treeline.
Please consider sharing your observations on the Mountain Information Network. Thank you to those that have already submitted this winter!
Snowpack Summary
Strong wind from the southwest and up to 30 cm of recent fresh snow has likely formed reactive storm slabs. The recent storm snow accumulations mean that 40-60 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. 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 areas where the snow feels stiff and/or slabby.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Choose relatively conservative lines and watch for clues of instability.
Problems
Storm Slabs
The recent new storm snow has formed reactive storm slabs. Strong southwest wind is creating deeper slabs on leeward slopes that could produce larger avalanches. Loose-dry sluffing will likely occur from steep terrain features in sheltered areas.
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. 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 19th, 2020 4:00PM
