Issued: Apr 29th, 2023 4:00PM
The alpine rating is Deep Persistent Slabs, Cornices and Loose Wet., the treeline rating is , and the below treeline rating is Known problems include
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.
A widespread natural and explosive triggered avalanche cycle up to size 3 occurred later in the afternoon on Friday and Saturday along with a skier-triggered size 2.5. Avalanches were a mix of wet loose, wet slabs, and deep persistent slabs, with many large avalanches running to the bottom of the runout zones.
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.
Valley bottoms may cool to near freezing on Saturday night, but expect above-freezing temperatures at treeline and above with only radiative cooling overnight. Freezing levels will climb quickly on Sunday morning reaching ~3500 m. Alpine temperatures between +5 and +10°C are expected with strong solar input and light SW winds.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of intense solar radiation.
- Avoid exposure to overhead avalanche terrain as temperatures increase.
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.
Cornices will be falling off this weekend. With the high freezing levels and direct sun exposure, the mountains will begin to shed. Do not exposure yourself to any corniced features or steep slopes below cornices as the day heats up.
Aspects: North, North East, East, South East, North West.
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.
Valid until: Apr 30th, 2023 4:00PM