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 Wind Slabs, Deep Persistent Slabs and Cornices.
jsmith,
Avalanche Canada
Forecast 10-15 cm of snow and moderate southerly wind may form reactive wind slabs on lee features in specific locations.
Concern for triggering very large deep persistent slab avalanches in the Haines Pass area remains. Avoid steep, rocky, and wind-affected areas where triggering slabs are more likely.
Summary
Confidence
Avalanche Summary
No avalanches were reported on Monday. However, observations in this region are currently very limited.
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
Forecast 10-15 cm of snow and moderate southerly wind may form reactive wind slabs on lee features in specific locations.
Cornices are very large and loom over slopes below like gargoyles. Cornice falls may trigger large avalanches on the slopes below.
A robust crust exists on all aspects up to approximately 1400 m and to ridgetop on sunny aspects.
A weak layer of surface hoar/crust/facets buried in early January is now around 100 cm down in most areas. A significant warming event or a large trigger (like a falling cornice) are the most likely things to activate this layer.
Weather Summary
Tuesday Night
Cloudy with isolated flurries; 0-5 cm / 40 km/h southeast ridgetop wind / Temperature at treeline around -5 C / Freezing level valley bottom
Wednesday
Cloudy with flurries; 5-15 cm / 35 km/h south ridgetop wind / Temperature at treeline around 1 C / Freezing level 1100 m
Thursday
Mostly cloudy with isolated flurries; 5-10 cm / 60 km/h south ridgetop wind / Temperature at treeline around 1 C / Freezing level 1100 m
Friday
Cloudy / 30 km/h south ridgetop wind / Temperature at treeline around 2 C / Freezing level 1300 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.
- Wind slabs may be poorly bonded to the underlying crust.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Cornice failure may trigger large avalanches.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Forecast 10-15 cm of snow and moderate southerly wind may form reactive wind slabs on lee features in specific locations.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of crust/facets down 100+ cm and/or weak facets at the bottom of the snowpack have recently become reactive.
Snowpack and avalanche observation data are currently very limited in this region which makes this kind of avalanche problem very difficult to forecast.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Cornices are very large and loom over slopes below like gargoyles. Cornice falls may trigger large avalanches on the slopes below.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 26th, 2023 4:00PM
