Avalanche Forecast
Issued: Mar 1st, 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.
swerner,
Avalanche Canada
6:30 AM PST UPDATE: 15 cm of new snow has blanketed the region overnight. Natural and human-triggered avalanche activity is expected on Thursday.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday, a few wet loose avalanches up to size 1 were reported below treeline.
On Monday, one size 1.5 natural storm slab was observed from a distance on a steep treeline convex roll, and a natural glide slab released size 2 from a south aspect at 1600 m and ran 300 m in length.
Looking forward to Thursday, natural and human-triggered storm slabs are likely. Storm slab reactivity is expected to persist for longer than is typical due to the weak surface they are sitting on.
Snowpack Summary
25 + cm of new snow and strong winds overnight Wednesday will add to the 30 cm of settling storm snow that fell last weekend. The new snow may have a poor bond to the underlying stiff wind slabs and faceted snow formed by recent 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 was reactive a week ago. 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 decrease significantly below 1500 m.
Weather Summary
Wednesday Night
New snow 10-20 cm. Alpine temperatures -7°C. Ridge wind southwest 30 to 70 km/h. Freezing level valley bottom.
Thursday
Snow up to 10-20 cm. Alpine temperatures -4 °C. Southwest wind 30 to 75 km/h. Freezing level 600 m.
Friday
Snow amounts 10 cm. Ridgetop wind 20 to 65 km/h from the southwest. Alpine temperatures -5°C. Freezing level 600 m.
Saturday
A mix of sun and cloud with isolated flurries. Alpine temperatures near -5 °C. Ridge wind northeast 15 km/h. Freezing level 700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy snowfall.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Closely monitor how the new snow is bonding to the crust.
Problems
Storm Slabs
Reactive storm slabs are likely on Thursday, especially on leeward slopes where wind/snow loading builds deeper slabs. 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.
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: Mar 2nd, 2023 4:00PM
