Avalanche Forecast
Issued: Mar 21st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Cornices, Deep Persistent Slabs and Wind Slabs.
zryan,
Avalanche Canada
Watch for isolated pockets of wind slab at upper elevation. Avoid overhead exposure to cornices, especially during the heat of the afternoon.
This MIN post has us concerned that a deep persistent slab problem is developing in the region with the warm temperatures. Use extra caution in thin, rocky terrain where triggering a deep weak layer is most likely.
Summary
Confidence
Avalanche Summary
On Sunday, a few natural size 1 loose wet avalanches were observed from steep terrain on solar aspects.
On Saturday, avalanches up to size 2.5 were reported in the Crowsnest South area which included some deep releases. This may be an indication that a deep persistent slab problem may be developing as warmer temperatures cause the upper snowpack to settle and form a slab over the weak layer at the base of the snowpack.
If you have any observations from this data sparse region, especially regarding a potential deep persistent slab problem, let us know what you are seeing by submitting a report to the Mountain Information Network.
Snowpack Summary
The snow surface consists of a sun crust on solar aspects, a rain crust below 1700 m, and wind-affected snow in exposed terrain at higher elevations. Small facets and/or surface hoar may also exist in shaded and wind-sheltered terrain.
A melt-freeze crust with facets above can be found 50 to 120 cm deep. The layer is currently dormant and has not produced any recent avalanche activity in the region but professionals are still tracking it to watch for signs of it waking up.
The weak layer at the base of the snowpack produced some large avalanches on the weekend and we are concerned that it might be becoming a more active problem with the current warm conditions. Caution is recommended in thin, rocky areas, mainly in the alpine but also possibly at treeline in some areas.
Weather Summary
Tuesday night
Clear. Alpine temperatures drop to a low of -7 °C. Light variable ridge wind. Freezing level at valley bottom.
Wednesday
Sunny. Alpine temperatures reach a high of 2 °C. Light variable ridge wind. Freezing level rises to 2200 metres.
Thursday
Sunny with cloudy periods. Alpine temperatures reach a high of -1 °C. Ridge wind southwest 15 to 40 km/h. Freezing level rises to 1900 metres.
Friday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -5 °C. Ridge wind 10 to 40 km/h from the southwest. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Cornice failures could trigger very large and destructive avalanches.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Cornices
Cornices may become weak during the heat of the afternoon. Use extra caution when traveling on ridges and avoid slopes with large cornices overhead during the heat of the afternoon.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
Some natural deep slab avalanche activity on Saturday has us concerned that the deep weak layer may be becoming a problem in the region. Check out this MIN post for an example of the type of avalanches that might be becoming a problem in the region. The concern is that the mild temperatures and sun may be causing the upper snowpack to settle into a reactive slab above the weak layer at the bottom of the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Isolated pockets of wind slabs may be found at higher elevations. Winds have recently shifted directions so wind slabs may exist on all aspects in exposed terrain.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 22nd, 2023 4:00PM
