Triggering the Feb 3 persistent weak layer remains the greatest concern. Use caution in areas with a snowpack depth lower than 200cm on shaded slopes above 2000m where several recent events have been triggered.
Expect to find developing new slabs with the incoming snow and winds.
On solar slopes expect thin new slabs to be found over sun crusts. On shaded slopes, the new snow buries spotty surface hoar and slabs may also incorporate the 10-30cm of dry snow from the last storm. In either case, check the bond to the old surfaces as these slabs develop into the weekend.
The Feb 3 crust/facet interface is down 50-100 cm and remains sensitive to skiers, with remote triggering observed in several instances, on northerly aspects in shallow snowpack areas. All of the recent avalanches that initiate on this layer step or gouge down to the basal facets / ground.
In the last week, there has been four size 2-3 avalanches that have all been remotely or accidentally triggered by skiers. All occurred on northerly aspects between 2000 - 2600m in thin snowpack areas.
These have all initiated on the Feb. 3rd crust/ facet interface and stepped down to basal facets / ground.
Be cautious on north slopes if there is no March 20 crust underfoot and the snowpack is less than 200cm. Infact: run away if the snowpack is less than 150cm!
Up to 15cm of storm snow covers sun crusts on solar aspects and up to 30 cm of dry snow on shaded slopes. Below this, the March 20th crust exists everywhere except north aspects above 1800.
Our main concern is thin snowpack areas (read: 200cm or less) on northerly aspects where there is no March 20 crust. Here the mid-pack Feb 3 facet / crust layer and the basal facets / depth hoar remain sensitive to triggering.
Deeper snowpack areas have fewer concerns.
Thursday evening: light snowfall will linger with freezing levels to valley bottom. Light to moderate SW winds at ridgetop.
The same light snowfall will continue Friday with freezing levels near 1500m and winds shifting NW.
Scattered flurries Saturday.
Skies clear and freezing levels rise to 2000m Sunday as winds increase: moderate to strong.
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