Avalanche Forecast
Issued: Apr 25th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Loose Wet.
jsmith,
Avalanche Canada
Forecast 25-35 cm of snow and strong southwesterly wind are expected to form reactive storm slabs.
Large, naturally triggered storm slab avalanches are likely on Wednesday.
Travel in avalanche terrain is not recommended.
Summary
Confidence
Avalanche Summary
A size 2.5 cornice fall was reported on a northerly aspect in the alpine on Monday. Additionally, a naturally triggered size 2 wind slab was observed on a northeast aspect in the alpine.
A fatal avalanche occurred north of Stewart on April 11th. It was a skier-triggered size 3 persistent slab avalanche that occurred on a northeast aspect in the alpine.
Most professional operations are now closed which means we have very little snowpack or avalanche observation data. Please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.
Snowpack Summary
Forecast 25-35 cm of snow and strong southwesterly wind are expected to form fresh storm slabs reactive to human triggers.
A crust exists up to ridgetop on south-facing slopes and on all aspects up to approximately 1300 m.
The primary concern is two buried weak layers down 40-140 cm deep in most areas. They include facets and surface hoar in shaded areas and a melt-freeze crust elsewhere. Numerous human-triggered persistent slab avalanches have occurred on these layers during the past week.
The mid and lower snowpack is considered generally strong and well-bonded. In the far northern reaches of the region, basal facets may exist which are currently considered inactive. This layer may become active with abrupt changes to the snowpack, such as rapid loading (heavy snowfall or rain) or prolonged warming.
Weather Summary
Tuesday Night
Snow; 15-30 cm / 60 km/h south ridgetop wind / Temperature at treeline around -3 C / Freezing level 1000 m
Wednesday
Snow ending mid-morning, then mostly cloudy; 10-15 cm / 50 km/h southwest ridgetop wind / Temperature at treeline around -3 C / Freezing level 1000 m
Thursday
Mix of sun and cloud / 40 km/h southwest ridgetop wind / Temperature at treeline around -1 C / Freezing level 1200 m
Friday
Sunny / 10 km/h west ridgetop wind / Temperature at treeline around 10 C / Freezing level rapidly rising to 3200 m!
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Use small low consequence slopes to test the bond of the new snow.
- Storm slabs in motion may step down to deeply buried weak layers resulting in very large avalanches.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
Problems
Storm Slabs
Forecast 25-35 cm of snow and strong southwesterly wind are expected to form fresh storm slabs reactive to human triggers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Numerous large persistent slab avalanches were triggered by riders in the alpine between April 10-12th. Most professional operations are now closed which means we have very little snowpack or avalanche observation data.
The primary concern is a layer of facets and surface hoar buried anywhere from 40-140 cm on shaded slopes. On other slopes, this layer is a crust with facets above. Avoid steep open slopes capable of producing large avalanches.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Even short periods of strong solar radiation may trigger wet loose avalanches on steep, sunny slopes.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Apr 26th, 2023 4:00PM
