Avalanche Forecast
Issued: May 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Deep Persistent Slabs.
JH,
Avalanche Canada
With no overnight refreeze this week, the entire snowpack is isothermal in most locations and will loose cohesion quickly with daytime warming or rainfall.
Large destructive natural avalanches remain possible. If air temps are warm or it is raining, travel in avalanche terrain is not recommended.
Summary
Confidence
High
Avalanche Summary
Natural activity was ongoing on Friday, with several large wet loose avalanches observed in the highway corridor.
This is capping off a very active week of spring avalanche activity - there was a widespread cycle of natural and controlled, wet loose and deep slab avalanches with numerous sz 3, and isolated sz 4's. Many avalanche paths failed down to ground once the avalanches were in motion.
Snowpack Summary
Warm temps have penetrated the snowpack creating a moist, isothermal snowpack on all aspects into the alpine. Buried crusts in the upper 50 cm are breaking down. Shallow snowpack features have loose, weak snow to ground.
20-40cm above the ground the Nov 17 basal weakness can still be found in many areas.
Weather Summary
Warm and dry weather will come to an end Friday, as a trough of low pressure brings light precip and dropping freezing levels (FZL).
Tonight: Cloudy periods, Alpine Low 3°C, FZL 2500m, Moderate E ridgetop wind.
Sat: Isolated showers/wet flurries, High 5°C, FZL 2600m, light S winds.
Sun: Scattered flurries (4cm), Low -1°C, High 1°C. FZL 2200m.
Mon: Isolated flurries, Low -1°C, High 5°C, FZL 2600m.
Terrain and Travel Advice
- Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Loose Wet
With intense solar radiation and no overnight refreeze, the snowpack is moist and weak. Wet loose avalanches could be triggered in steep terrain. We have observed these loose avalanches stepping down to the basal weakness at Treeline elevations and lower.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Several hot days with no overnight refreeze has warmed and destabilized the snowpack. This early season basal weakness has woken up below 2000m and is producing very destructive avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: May 7th, 2023 4:00PM
