Avalanche Forecast
Issued: Feb 25th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
CJ,
Avalanche Canada
Wind transport, new snow, and deeper buried weak layers will keep the avalanche hazard elevated on Sunday.
Conservative terrain choices with minimal overhead hazard are recommended until the winds diminish and the snowpack adjusts to the recent loading.
Summary
Confidence
Avalanche Summary
Natural avalanche activity slowed slightly on Saturday, but numerous natural wind slabs, persistent slabs and deep persistent slabs up to size 3+ have been observed over the past several days. Ski hills also continue to trigger wind slabs with explosives and ski cutting, with some avalanches stepping down to the deeper layers in the snowpack.
Snowpack Summary
20-50 cm of recent storm snow is now faceting and being redistributed by strong SW winds at alpine and treeline elevations. Wind effect and new wind slabs exist on most aspects above treeline. These windslabs overlie the various Jan PWL interfaces of sun crusts, facets and surface hoar down 70-110 cm. The weaker Nov 16 basal facet layer is down 100-180 cm and still produces mod-hard sudden collapse test results. Deeper snowpack areas west of the divide have a stronger and more supportive lower snowpack than areas to the east.
Weather Summary
Sunday will see light snow flurries for most of the region with a few cm's of new snow in eastern regions and perhaps as much as 5 to 10 cm in areas along the divide. Ridgetop winds remain in the moderate to strong range out of the SW. Alpine temperatures are expected to be between -10 to -15°C.
Terrain and Travel Advice
- Make conservative terrain choices and avoid overhead hazard.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Cornice failure may trigger large avalanches.
Problems
Wind Slabs
20 to 80 cm of storm snow fell in the past week with strong winds from muliple directions. This created extensive wind effect, fresh cornice growth, and new wind slabs at treeline and above. These wind slabs are slowly becoming more difficult to trigger, but if triggered they could step down to the deeper weak layers and create larger avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Three persistent weak layers formed in January are down 70-100 cm. The biggest concern is triggering these buried suncrusts on steep solar slopes, but weaker facets and isolated surface hoar can be found on the same interface on shaded aspects. Key an eye out for these layers in steeper terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak facets and depth hoar are present at the bottom of the snowpack in most places. Last week's storm overloaded this interface resulting in numerous large avalanches running long distances. The snowpack is slowly adjusting to the new load, but natural triggering is still a concern with ongoing wind loading and cornice failures, and human triggering is still possible especially in shallower snowpack or rocky areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 26th, 2023 4:00PM
