Avalanche Forecast
Issued: Feb 21st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
rgoddard,
Avalanche Canada
Northeast winds will have generated fresh wind slabs.
Triggering a deep persistent slab remains possible, especially in areas with a thin snowpack..
Summary
Confidence
Moderate
Avalanche Summary
No significant avalanches were reported in the past few days but observations have been limited.
Looking forward to Tuesday, we expect fresh, reactive wind slabs to form in a reverse loading pattern and at lower elevations than you might typically expect. These wind slabs may be particularly reactive where they overlie a crust.
On Thursday, there was a report of a natural deep persistent slab avalanche, size two,from the northern part of the region. It was on a northeast aspect in the alpine. Deep persistent slab avalanches like this one continue to be reported at least once a week in shallow snowpack areas.
Snowpack Summary
Monday saw 30 to 40 cm of new snow. This has likely been redistributed by northeast winds in exposed areas at most elevations.
Several layers of facets, crusts/surface hoar can be found in the top 1.5 meters of the snowpack. For the most part, the mid-pack is generally strong.
Weak layers of note from November and December are near the bottom of the snowpack, 150 to 200 cm from the surface.
The total height of snow at treeline is between 200 and 280 cm.
Weather Summary
Tuesday Night
Clear, no accumulation, winds northeast 35 km/h, treeline temperatures, -13 to -18 °C.
Wednesday
Sunny, no accumulation, winds northeast 35 km/h, treeline temperatures -20 °C.
Thursday
Sunny with some clouds, no accumulation, winds northeast 35 km/h gusting to 50, treeline temperatures -23 °C.
Friday
Mostly cloudy, up to 5 cm accumulation, winds west 50 km/h, treeline temperatures around -20 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Avoid areas with a thin or variable snowpack.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
Problems
Wind Slabs
Northeasterly winds will redistribute 20 to 40 cm of recent new snow into fresh, reactive wind slabs. These slabs will form in a reverse loading pattern and at lower elevations than expected. Wind slabs may be particularly reactive where they overlie a crust.
Aspects: North, South East, South, South West, West, North West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Over the past few weeks we have recieved reports of large deep persistent slab avalanches. Triggering an avalanche on deeply buried facets is unlikely but very consequential. Avoid shallow, steep and rocky start zones at treeline and above where triggering a deep persistent slab could be possible.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 22nd, 2023 4:00PM
