Avalanche Forecast
Issued: Apr 18th, 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.
LP,
Avalanche Canada
20-35 cm of new snow fell with strong SW winds as a cold front passed through Monday, resulting in increased avalanche hazard. Moderate terrain choices with limited overhead hazard are recommended until the storm snow settles and bonds.
Summary
Confidence
Moderate
Avalanche Summary
On Monday, Yoho and Lake Louise got 30-45 cm of new snow and saw natural avalanche activity out of steep terrain up to size 3 in the storm snow, On Tuesday, Lake Louise patrol reported explosive triggered avalanches to size 1.5, 25-30 cm deep, involving the storm snow.
Snowpack Summary
20-35 cm of storm snow arrived with strong SW winds on Monday. The storm snow sits over buried sun crusts that are present to ridge crests and faceted layers on shady aspects. Multiple buried crusts are present in the top 50-70 cm on solar aspects. The basal depth hoar is present but is only a concern in thin areas.
Lower elevations have a temperature crust on all aspects.
Weather Summary
5-10 cm expected Tuesday night, with the greater amounts between Banff and Highwood Pass.
Another 5-10 cm is expected on Wednesday. Amounts are variable given the convective nature of the snowfall, where some locations may receive greater than 10 cm.
Winds should remain light.
Terrain and Travel Advice
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Problems
Storm Slabs
Areas with 15+ cm of fresh snow will have a storm slab problem. The new snow may fail naturally and will be reactive to human triggering especially over buried sun crusts. Lee areas with newly formed wind slabs and fresh cornices are also a concern.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The November basal facets and depth hoar have been mainly dormant in this region and we have seen few avalanches on this layer. Watch for thin snowpack spots or places exposed to large loads like cornices where triggering this is more likely.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 19th, 2023 4:00PM
