Look for fresh pockets of wind slabs from southwesterly winds in the alpine and treeline lees. Wind slabs are most reactive during their formation so use extra caution around freshly wind-loaded features.
Avoid shallow, rocky snowpack areas where the snowpack transitions from thick to thin and triggering the deep persistent weak layer is still possible.
Strong southwesterly winds are forming new wind slabs on lee slopes in the alpine and at treeline. Avoid steep, rocky wind-affected areas where trigger slabs are more likely.
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.
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. Last 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.
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Strong southwest winds are redistributing available snow into fresh wind slabs at alpine and treeline lees. In the alpine fresh wind slabs cover scoured polar aspects. 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.
Thursday night
Mainly cloudy with clear periods and isolated flurries, trace accumulation. Southwesterly ridgetop winds 40 km/h. Treeline temperatures -2 ˚C. Freezing levels 1200 m.
Friday
Mainly cloudy with isolated flurries, 2-5 cm accumulation. Southwesterly ridgetop winds 40 km/h. Treeline temperatures -1 ˚C. Freezing levels 1400 m.
Overnight cloudy with isolated flurries, 10-15 cm accumulation.
SaturdayMainly cloudy with isolated flurries, 2 cm accumulation. Southwesterly ridgetop winds 20 to 40 km/h. Treeline temperatures -1 ˚C. Freezing levels 1500 m.
SundayCloudy with sunny periods and isolated flurries, 2 cm accumulation. Southwesterly ridgetop winds 20 km/h. Treeline temperatures -1 ˚C. Freezing levels 1500 m.
More details can be found in the Mountain Weather Forecast.
