Avalanche Forecast
Issued: Mar 20th, 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
Two very large (size 2.5-3) naturally triggered wet loose avalanches were reported on steep southerly aspects in the alpine on Sunday.
Additionally, numerous natural size 1-1.5 wet loose avalanches were reported on sunny aspects at treeline and above.
A naturally triggered size 1.5 wind slab was also reported on a north aspect 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
Monday Night
Clear skies / 10 km/h northeast ridgetop wind / Temperature at treeline around -9 C / Freezing level valley bottom
Tuesday
Sunny / 10 km/h north ridgetop wind / Temperature at treeline around -1 C / Freezing level 1900 m
Wednesday
Sunny / 10 km/h southwest ridgetop wind / Temperature at treeline around 1 C / Freezing level 2100 m
Thursday
Mix of sun and cloud / 20 km/h south ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 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 21st, 2023 4:00PM
