Avalanche Forecast
Issued: Apr 30th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Cornices and Loose Wet.
AL,
Avalanche Canada
Avalanche control is scheduled for Monday, May 1st on Mt Whymper. No recreating in this area. A major avalanche cycle is underway. Avoid all avalanche terrain. Avalanches will run to the valley bottom as the day heats up. Hikers should pay attention to avalanche warning signs at locations like Emerald Lake, Lake Louise and Sulphur Mountain.
Summary
Confidence
High
Avalanche Summary
A widespread natural avalanche cycle to size 4 started Friday and has continued through the weekend. A mix of wet loose, wet slabs, and deep persistent slabs, have been running full path. Expect this natural avalanche cycle to continue through the week as the temperature remain elevated.
Snowpack Summary
The heat is on! After a light refreeze overnight, sky-high freezing levels will melt and destabilize the snowpack early in the day. Expect wet snow on all solar aspects and unsupportive isothermal snow (slush) at lower elevations. The weak basal facets are a significant concern in thinner snowpack areas.
Weather Summary
Valley bottoms may cool to near freezing on Sunday night, but expect above-freezing temperatures at treeline and above with only radiative cooling overnight. Freezing levels will climb quickly on Monday morning reaching ~3500 m. Alpine temperatures between +5 and +10°C are expected with strong solar input and light S winds.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of intense solar radiation.
- Avoid exposure to overhead avalanche terrain as temperatures increase.
Problems
Deep Persistent Slabs
We are seeing lots of avalanche activity on the weak facets and depth hoar at the bottom of the snowpack as the upper snowpack heats up and looses cohesion. These avalanches are easily triggered, often large and running long distances.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
With the high freezing levels and direct sun exposure, the mountains will begin to shed. Do not expose yourself to any corniced features or steep slopes below cornices as the day heats up.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
We expect wet slabs and wet loose avalanches on all aspects and elevations, especially when the sun cooks the slopes. Slush and wet snow will run like water down gullies and through rock bands: the spring melt is on.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: May 1st, 2023 4:00PM
