Avalanche Forecast
Issued: Feb 1st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Watch for wind-loaded pockets, especially just below ridgetops and in extreme and very steep terrain.
Avoid shallow, rocky snowpack areas where the snowpack transitions from thick to thin and triggering the deep persistent weak layer is still possible.
Summary
Confidence
Avalanche Summary
Reports from the past few days are limited to one small wind slab avalanche (size 1.5) from Monday. It occurred naturally on a reverse-loaded feature in the Hurley area. On Friday, a size 2.5 skier-triggered deep persistent slab occurred in the Birkenhead area. This avalanche was remotely triggered, meaning the skier was a distance away from the slab when it occurred (100 m above). It occurred on a wind-loaded slope in the alpine during a period of strong solar radiation. The crown was 150 cm deep.
Please continue to share any observations or photos on the Mountain Information Network.
Snowpack Summary
This week moderate winds varying in direction have affected all exposed areas at alpine and treeline, scouring slopes and creating pockets of stiff wind slabs. In sheltered areas, 10 to 20 cm of recent storm snow is faceting with cold temperatures. A surface crust can be found below 1800 m and all elevations steep solar aspects.
In the midpack, a weak layer can be found 50 to 100 cm deep, as a decomposing crust, or in many places, it's more of a soft and weak section of the snowpack. There is a widespread weak layer of facets and depth hoar at the bottom of the snowpack.
Generally, the snowpack in this region is weak and shallow. Snowpack depths around treeline are highly variable and range between 150 to 250 cm.
Weather Summary
Wednesday night
Mainly cloudy with isolated flurries, trace amounts accumulation. Southwesterly ridgetop winds 30 to 40 km/h. Treeline temperatures -5 ˚C. Freezing levels 600 m.
Thursday
Mix of sun and cloud. Southwesterly ridgetop winds 30 to 50 km/h. Treeline temperatures -2 ˚C. Freezing levels 1000 m.
FridayMainly cloudy with scattered flurries, 5 cm accumulation. Southwesterly ridgetop winds 40 to 60 km/h. Treeline temperatures -3 ˚C. Freezing levels 1000 m.
SaturdayMainly cloudy with scattered flurries, 5 cm accumulation. Southwesterly ridgetop winds 40 to 60 km/h. Treeline temperatures -1 ˚C. Freezing levels 1400 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be carefull around freshly wind loaded features.
- Carefully evaluate steep lines for wind slabs.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
Problems
Wind Slabs
Moderate gusting to strong southwesterly winds are forming new wind slabs on north and east facing slopes, while previous outflow winds have left stiff wind slabs on south and west facing slopes. Wind slabs may be particularly reactive where they overlie a hard crust layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, unsupported, wind-loaded terrain or by first triggering a layer in the upper snowpack. Evidence suggests this layer may be more problematic in the Hurley and Birkenhead areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2023 4:00PM
