Avalanche Forecast
Issued: Nov 27th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
TRettie,
Avalanche Canada
Increasing temperatures, wind and precipitation embedded within this storm will test the snowpack. Avalanches could run far and step down to deeper layers.
Summary
Confidence
Weather Forecast
Saturday night: A storm will hit the region tonight bringing up to 10mm of precipitation. The North part of the region will see freezing levels rise to 1500m and moderate to strong Southwest winds. The Southern part of the region will see more intense weather, freezing levels will rise to 2000m and winds will be strong from the Southwest.
Sunday: Freezing levels will rise to 2000m throughout the range. 10mm of precipitation is expected for most of the region except for the Bugaboos where up to 35mm is expected. Winds will be strong from the Southwest.
Monday: Some light flurries throughout the day. Freezing level 1700m and light to moderate Southwest winds.
Tuesday: Some light flurries with light to moderate Southwest winds. Freezing levels around 1800m.
Avalanche Summary
Several storm slabs up to size 2 were reported in the Purcells on Friday. We suspect a natural cycle will take place early Sunday morning with the incoming storm.
Snowpack Summary
The incoming storm will form new storm slabs and wind slabs in the treeline and alpine. A surface hoar layer has been observed down 20cm in some parts of the range. A mid November rain crust is down 30 to 60cm and exists below 2100m.
Several early season crusts exist throughout the lower pack. A late October facet/crust layer sits at the bottom of the snowpack. it likely only exists above 1900m.
Terrain and Travel
- Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.
- Use increased caution at all elevations. Storm snow is forming touchy slabs.
Problems
Storm Slabs
Storm slabs will form with new snow and wind. The most reactive deposits will be around ridgelines and in lee-ward terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of Facets at the base of the snowpack from late October has been observed. We need more information on the distribution of this layer but we suspect it only exists at high treeline elevations and into the alpine. It is possible that the incoming storm could produce avalanches on this layer.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Nov 28th, 2021 4:00PM
