Avalanche Forecast
Issued: Mar 13th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
CG,
Avalanche Canada
A healthy snowfall at the Pass has reset the slopes, but the storm snow will take some time to properly bond to the underlying layers, especially where the snow landed on a crust.
Summary
Confidence
Avalanche Summary
A natural avalanche cycle is underway (Monday afternoon) in the highway corridor as the snow falls and the temps rise. Numerous slides in the sz 2-3 range have been detected from most aspects.
Natural activity should subside quickly with dropping temps on Tues.
Snowpack Summary
Warm storm snow has fallen on a variety of surfaces (wind crust, sun crust, or surface hoar), accompanied by gusty SW winds. This storm slab is presently widespread through the region.
The generally strong snowpack sits on a deep persistent basal weakness of rounding facets/decomposing crust near the ground. Uncertainty surrounds this layer; each major snowfall has the potential to finally overload this weakness, resulting in large avalanches.
Weather Summary
The main thrust of moisture has passed the region, with unsettled weather Tues and general clearing/cooling Wed/Thurs.
Tonight: Flurries, trace snow, Alp low -14*C, mod/strong SW winds, freezing level (FZL) valley bottom
Tues: mix of cloud/sun, Alp high -10*C, light/mod S winds, 900m FZL
Wed: mix of sun/cloud, isolated flurries, Alp high -10*C, light/mod W winds, 900m FZL
Terrain and Travel Advice
- Closely monitor how the new snow is bonding to the crust.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Cornice failures could trigger very large and destructive avalanches.
Problems
Storm Slabs
Storm slabs now dominate the upper snowpack, with ~30cm of warm snow sitting on a variety of old surfaces (wind crust, sun crust, surface hoar). Deeper storm slab exists in wind loaded areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Monday's storm brought ~30cm of heavy, warm snow at higher elevations, with a hint of rain below Treeline. This additional load will test the integrity of the deep persistent weak layer. An avalanche on this layer would be very destructive, likely run full path or further, and be of high consequence.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 14th, 2023 4:00PM
