Avalanche Forecast
Issued: Mar 22nd, 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.
jpercival,
Avalanche Canada
Additional snow from the incoming storm is likely to increase reactivity on previously buried surface hoar. Be cognizant of increased hazard, especially on wind loaded features.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday, ongoing and continued widespread large (size 2) loose wet avalanches were observed and reported by all operations within the forecast area. These avalanches were at all elevations and confined to mostly south aspect terrain with a few noted cornice collapse occurring.
On Monday, a widespread natural loose wet avalanche cycle was observed, up to 2.5, below treeline. Numerous wet loose avalanches were observed size 1-1.5 on solar aspects at alpine and treeline. Three skier triggered, size 1, windslab avalanches were reported.
On Sunday, two, natural size 3 persistent slab avalanches were observed. Both these avalanches ran to valley bottom and are suspected to have released on a weak layer of surface hoar. Two, size 1.5 persistent slab avalanches were remotely triggered by a helicopter on the same layer.
Snowpack Summary
Upper snowpack continues to settle rapidly as warm temperatures have persisted. Below 1800m moist surface snow exists on all aspects, with a melt feeze crust present on south aspects that extends up to 2000 m.
At elevations treeline and below, a weak layer of surface hoar is found 20-50 cm down in sheltered terrain and continues to be reactive to skier traffic.
A second weak layer of surface hoar and/or faceted grains may be found about 60 cm deep, particularly on shaded aspects near treeline.
The lower snowpack presents as consolidated and strong.
Weather Summary
Wednesday Night
Mainly cloudy with isolated flurries, trace to 1 cm of accumulation. Moderate southwest winds at ridgetop. Treeline temperature -2°C. Freezing levels descend to 500 m.
Thursday
Mainly cloudy with snowfall, 5 to 10 cm of accumulation. Moderate southwest winds at ridgetop. Treeline temperature 0°C. Freezing levels 900 m.
Friday
Mainly cloudy with snowfall, 5 to 10 cm of accumulation. Light north winds at ridgetop. Treeline temperature -1°C. Freezing levels 800 m.
Saturday
Partly cloudy with isolated flurries, trace accumulation. Light north winds at ridgetop. Treeline temperature 0°C. Freezing levels 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be carefull around freshly wind loaded features.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Problems
Wind Slabs
Southwest winds will redistribute new and available snow into fresh wind slabs in exposed lees at higher elevations. A buried layer of surface hoar is increasing the reactivity and propagation of wind slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of large surface hoar is found down 20-50 cm. This layer has been most active in the Shames region however with additional load we may see wider spread reactivity on this layer. Use caution on sheltered and shaded slopes where surface hoar is more likely to be preserved.
Aspects: North, North East, East, West, North West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 23rd, 2023 4:00PM
