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 Wind Slabs, Loose Wet and Deep Persistent Slabs.
jsmith,
Avalanche Canada
Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Summary
Confidence
High
Avalanche Summary
Numerous naturally triggered wet loose avalanches up to size 3 (very large) were reported on steep sunny aspects in the alpine on Monday.
A helicopter landing on a ridge triggered a size 2 wind slab on the steep slope below. It was a northerly aspect in the alpine.
A couple rider triggered size 1 wind slab avalanches were also reported on northerly aspects in the alpine.
Snowpack Summary
Expect to find a melt-freeze crust on the surface of all aspects at treeline and below and on sunny aspects in the alpine. Solar radiation will break down the crust on sunny slopes throughout the day.
Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.
30-50 cm down there is a sun crust on sunny aspects and surface hoar (3-10 mm) on isolated shady and sheltered slopes.
The mid-snowpack is generally strong but the lower snowpack is a different story..
The November facets are still prominent at the base of the snowpack. They are showing signs of improving but this layer remains a significant concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Weather Summary
Tuesday Night
Clear skies / 10 km/h northeast ridgetop wind / Temperature at treeline around -8 C / Freezing level valley bottom
Wednesday
Sunny / 10 km/h southwest ridgetop wind / Temperature at treeline around 0 C / Freezing level 2000 m
Thursday
Mix of sun and cloud / 10 km/h southwest ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 m
Friday
Mostly cloudy with isolated flurries; 0-5 cm / 10 km/h west ridgetop wind / Temperature at treeline around -8 C / Freezing level 1300 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Cornice failure may trigger large avalanches.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Wind Slabs
Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.
Aspects: North, North East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Strong solar radiation will increase the likelihood of wet loose avalanches on sunny aspects in the alpine.
Aspects: South East, South, South West, West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 22nd, 2023 4:00PM
