Avalanche Forecast
Issued: Dec 20th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Dry and Deep Persistent Slabs.
Mark Herbison,
Parks Canada
An excellent day to check out the local ski area.
Avoid overhead hazard and avalanche terrain.
Summary
Weather Forecast
The infamous atmospheric river did not disappoint today and the storm continues on through Saturday night with another 30-40cm forecasted. Temps will remain mild on Saturday with an alpine high of -4 and a freezing level up to 1500m. Winds will be moderate, gusting to strong from the S-SW. Clearing trend on Sunday with cooler temps and light winds.
Snowpack Summary
20-35cm of storm snow in the past 24hrs accompanied by moderate Southerly winds is forming a storm slab in the alpine and at tree line. Below the new snow the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust is present up to 2500m and ~30 cm up from ground. Snowpack depths at treeline range from 90-160 cm.
Avalanche Summary
Poor visibility has obscured any avalanche observations, but a natural avalanche cycle is either happening or about to happen. Avoid avalanche terrain.
Confidence
Intensity of incoming weather systems is uncertain on Saturday
Problems
Storm Slabs
A touchy storm slab is forming and will become more sensitive to human triggering as the storm continues on Saturday.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
- Use caution in lee areas in the alpine and treeline. Storm snow is forming reactive slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
As the snow accumulates, expect sluffing and point releases from steep, rocky terrain and gullies.
- If triggered dry loose point releases can form deeper deposits in terrain traps.
- Be careful of loose dry power sluffing in steep terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The weak, faceted mid and lower pack is being stressed by the new storm snow and might be reaching threshold. Lots of uncertainty surrounds this layer, but if triggered it would result in a large avalanche.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 21st, 2019 4:00PM
