Avalanche Forecast
Issued: Feb 27th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Storm slabs may remain sensitive to human-triggering, particularly in wind-loaded areas.
Take a cautious approach and investigate the bond between the new snow and the old surface before comitting to your line.
Summary
Confidence
Moderate
Avalanche Summary
Observations have been limited throughout the storm last weekend. On Monday, one size 1.5 natural storm slab was observed from a distance on a steep treeline convex roll.
Looking forward to Tuesday, human-triggered storm slabs remain likely, especially in wind-loaded areas. Storm slab reactivity is expected to persist for longer than is typical due to the weak surface they are sitting on.
Please continue to post your reports and photos to the Mountain Information Network.
Snowpack Summary
An additional 5-10 cm will accumulate throughout the day. This overlies last weekend's 15-30 cm of new snow. In some areas, this new snow has bonded poorly to the underlying surface, consisting of stiff wind slabs and near-surface faceting formed by recent wind and cold temperatures.
A melt-freeze crust formed in mid-January is buried up to 90-140 cm deep. In some areas, small faceted crystals can be found above the crust. This layer has been reactive during the storm Tuesday night and Wednesday this week. The snow below this layer is well consolidated.
Snowpack depths are just below seasonal averages. Total amounts range from 150 to 300 cm at treeline, but decreases significantly below 1500 m.
Weather Summary
Monday night
Clear periods. Alpine temperatures drop to a low of -8 °C. Ridge wind light from the south. Freezing level at valley bottom.
Tuesday
Flurries in the afternoon, trace to 10 cm of accumulation. Alpine temperatures reach a high of -2 °C. Light variable ridge wind. Freezing level 600 meters.
Wednesday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -5 °C. Ridge wind southwest 15 km/h gusting to 45 km/h. Freezing level 500 meters.
Thursday
Cloudy with snowfall, 5-15 cm of accumulation. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 30 km/h to 60 km/h. Freezing level 800 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Give the new snow time to settle and stabilize before pushing into bigger terrain.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Carefully monitor the bond between the new snow and old surface.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Storm Slabs
An additional 5-10 cm will accumulate over last weekend's 15-30 cm of storm snow. In many areas, this new snow may be bonding poorly to the underlying surface and storm slab reactivity may persist for longer than is typical. Deeper and more reactive deposits will exist in wind-loaded areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A crust formed in mid-January can be found down 80 to 120 cm. In areas around the Coquihalla, facets can be found sitting on the crust. This layer is of greatest concern with large triggers, such as a cornice fall, or by first triggering a smaller avalanche that could step down to this interface.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 28th, 2023 4:00PM
