Avalanche Forecast
Issued: Apr 12th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
jsmith,
Avalanche Canada
Lingering wind slabs may remain reactive to human triggers on lee aspects in the alpine.
Watch for recently formed and reactive wind slabs as you transition into wind affected terrain.
Summary
Confidence
Moderate
Avalanche Summary
A size 2, cornice triggered wind slab was reported on a north aspect in the alpine on Sunday. See MIN
On Saturday a rider triggered a cornice fall from a distance, which produced a size 3 persistent slab avalanche on a northeast aspect at 1750 m. The avalanche was 200 cm deep and was suspected of having failed on the layer of facets above a crust buried in January.
Observations are limited at this time of year, please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.
Snowpack Summary
20-30 cm of recent soft snow may have seen some redistribution by recent wind but above 1200 m, it remains largely available for wind transport. Below 1200 m, moist snow or a thin crust may exist at or near the surface.
The new snow sits over previously wind-affected snow on north and east facing slopes and a crust on south facing slopes.
A weak layer of surface hoar/crust/facets buried in early January is now buried over 1 m deep in most areas. This layer has produced recent avalanche activity and remains a concern in terrain where the snowpack is thin. The lower snowpack consists of basal facets, particularly in shallow areas.
Weather Summary
Wednesday night
Cloudy with isolated flurries; 0-5 cm / 20 km/h south ridgetop wind / Temperature at treeline around -8 C / Freezing level valley bottom
Thursday
Mostly cloudy with isolated flurries; 0-3 cm / 20 km/h southwest ridgetop wind / Temperature at treeline around -5 C / Freezing level 800 m
Friday
Mostly sunny / 10 km/h east ridgetop wind / Temperature at treeline around -5 C / Freezing level 900 m
Saturday
Cloudy with flurries; 3-10 cm / 15 km/h east ridgetop wind / Temperature at treeline around -4 C / Freezing level 1000 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Cornice failure may trigger large avalanches.
- Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.
Problems
Wind Slabs
Lingering wind slabs may remain reactive to human triggers on lee aspects in the alpine.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
A layer of facets sitting on a crust buried in January has recently been reactive. Triggering is most likely in areas where the snowpack is thin and weak, or with a heavy load like a cornice fall or the weight of a smaller avalanche in motion triggering this deeper layer.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 13th, 2023 4:00PM
