Avalanche Forecast
Issued: Feb 20th, 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.
zryan,
Avalanche Canada
Fresh reactive wind slabs are expected to form throughout the day as northeasterly winds redistribute yesterday's storm snow.
Avoid wind-loaded slopes and be especially cautious in shallow snowpack areas where triggering a deep persistent slab remains possible.
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.
One natural size two deep persistent slab was reported last Thursday in 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
Up to 30 cm of new snow arrived on Monday. Northeasterly winds are expected to redistribute this new snow into fresh, reactive wind slabs.
Several layers of facets, crusts or surface hoar can be found in the top 1.5 meters of the snowpack.
In shallow snowpack areas layers of facets from November and December are near the bottom of the snowpack and have likely been responsible for some large avalanches.
Weather Summary
Monday night
Mainly cloudy with scattered flurries, trace to 5 cm accumulation. Alpine temperatures drop to a low of -16 °C. Ridge wind northeast 25-50 km/h. Freezing level at valley bottom.
Tuesday
Sunny with cloudy periods. Alpine temperatures reach a high of -16 °C. Ridge wind northeast 20 km/h gusting to 45 km/h. Freezing level at valley bottom.
Wednesday
Sunny. Alpine temperatures reach a high of -20 °C. Ridge wind east 25 km/h gusting to 50 km/h. Freezing level at valley bottom.
Thursday
Sunny with cloudy periods. Alpine temperatures reach a high of -22 °C. Ridge wind east 25-40 km/h. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
- 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.
Problems
Wind Slabs
Northeasterly winds will redistribute 20-40 cm of recent new snow into fresh, reactive wind slabs. These slabs will form in a reverse loading pattern and at lower elevations than you might typically expect. 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 21st, 2023 4:00PM
