Avalanche Forecast
Issued: Mar 17th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
jsmith,
Avalanche Canada
Storm slabs formed earlier in the week may continue to be reactive to human triggers at upper elevations; especially on sunny aspects.
Northerly aspects at upper elevations will offer the best riding conditions.
Summary
Confidence
Moderate
Avalanche Summary
Numerous explosive triggered storm slab avalanches up to size 2.5 were reported on primarily sunny aspects at treeline and above on Thursday. They were failing on a crust down 30-40 cm.
Additionally, two explosive triggered very large (size 2.5) persistent slab avalanches were reported on east and northwest aspects in the alpine southwest of Nelson. It is uncertain which layer these avalanches failed on, but they were suspected to be 100-200 cm deep.
Snowpack Summary
Expect to find sun crust on the surface of steep, sunny aspects.
Strong solar radiation has settled the 30-50 cm of recent snow into a storm slab which has been especially reactive to human triggers on sunny aspects where it overlies a crust.
Strong south wind during the storm earlier in the week have added to slab formation on lee aspects at treeline and above.
The recent snow is sitting on a variety of surfaces. These include sun crust on sunny aspects and surface hoar (3-5 mm) on some shady and sheltered slopes.
A layer of surface hoar or sun crust, aspect dependent, that was formed in mid-February can be found down 80 to 110 cm.
The lower snowpack includes a layer of weak sugary facets near the ground. These facets are slowly gaining strength and no recent avalanches have been reported on this layer. However, we continue to track the layer and watch for any signs of it becoming active.
Weather Summary
Friday Night
Clear skies / 10 km/h south ridgetop wind / Temperature at treeline around -7 C / Freezing level valley bottom
Saturday
Mostly sunny / 10 km/h south ridgetop wind / Temperature at treeline around -2 C / Freezing level 1800 m
Sunday
Increasing cloudiness / 20 km/h southeast ridgetop wind / Temperature at treeline around -1 C / Freezing level 1900 m
Monday
Cloudy with isolated flurries; 3-10 cm / 20 km/h southeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 1600 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Avoid exposure to slopes that have cornices overhead.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
Problems
Storm Slabs
Storm slabs formed earlier in the week may continue to be reactive to human triggers at upper elevations; especially on sunny aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 18th, 2023 4:00PM
