Avalanche Forecast
Issued: Nov 30th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
jpercival,
Avalanche Canada
Increasing and strong north winds are transporting a lot of light and dry snow, and wind slabs are building! The avalanche danger is heightened in the alpine.
Summary
Confidence
Moderate
Avalanche Summary
A helicopter explosive mission near Sukunka creek triggered a few size-one wind slab avalanches. One windslab size 2.5 (very large) was triggered with a large explosive on a south aspect at 2200 m. The avalanche was described as fast-moving, with the powder debris splitting onto two separate avalanches.
Reports from an observation flight on Monday over the Sentinel pass indicate that a past natural storm slab avalanche cycle occurred in steep rocky terrain only. Avalanches in this cycle were up to size 2.5 (very large).
Observation of windslabs naturally triggered have been reported on north aspect terrain between 1350 m and 1450 m, likely occurring on the reported melt-freeze crust.
Please consider sharing your observations via the Mountain Information Network to help us and fellow recreationists.
Snowpack Summary
The storm last week delivered to this region between 40 to 80 cm of new snow. Winds were strong from the southwest during this event, and terrain exposed to this wind has been stripped with new snow building into wind slabs on north aspects.
During the past storm event a period of warming brought rain up to nearly 1500 m and now a melt-freeze crust can be found down 70 cm.
During mid-November, a period of cooling temperatures created a weak layer above the 1200-meter mark and can be found down 80 cm.
Average snowfall depths are around 20 to 60 cm below the treeline and 100 to 120 cm in the alpine.
Weather Summary
Wednesday Night
Cloudy with very light flurries, accumulation 1 to 3 cm, 50 km/h northeast wind, treeline temperature -25 °C.
Thursday
Clear sky no forecast precipitation, 30 km/h northwest wind, treeline temperature -27 °C.
FridayClear sky no forecast precipitation, 10 km/h northwest wind, treeline temperature -27 °C.
SaturdayMostly cloudy with very light flurries, accumulation 1 cm, 20 km/h southwest wind, treeline temperature -19 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Make observations and assess conditions continually as you travel.
Problems
Wind Slabs
Intense wind transport of 70 cm of light and dry snow occurred from strong north through east winds. Wind slabs will be found on all aspects with growing hazards focused on south through west aspects.
Use caution when entering terrain below ridgelines and in areas that harbor deep pillows of wind-deposited snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
The past week's storm snow is forming a slab that may not bond well to the underlying snowpack. The layer of concern formed mid-November is composed of faceted grains, surface hoar, and a hard crust and can be found down 40 to 80 cm.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 1st, 2022 4:00PM
