Avalanche Forecast
Issued: Feb 2nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
Take stock of new snow depths and wind effect as you gain elevation on Monday - these are the building blocks of the current avalanche danger and both will increase with elevation.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Sunday night: Clear. Light west winds.
Monday: A mix of sun and cloud with isolated flurries. Calm or light variable winds. Alpine high temperatures around -15.
Tuesday: Mainly sunny with cloud increasing over the day. Light to moderate southwest winds increasing over the day and overnight. Alpine high temperatures around -13.
Wednesday: A mix of sun and cloud with isolated flurries. Moderate to strong southwest winds. Alpine high temperatures around -8.
Avalanche Summary
Reports from Friday showed small (size 1) wind slabs able to be triggered with ski cutting in the Castle area. More intense snowfall and wind throughout Saturday are likely to have spurred a natural avalanche cycle, focused in high elevation, wind-exposed areas.
On Thursday a cornice fall released a size 2 slab avalanche on the slope below on an east aspect at 2150 m.Â
On January 16th, a natural, size 2 wind slab stepped down to the deep persistent basal facets below a rock band, details here.
While avalanche danger is now low in areas where a new crust has capped the snowpack, reactive wind slabs are likely to exist in the highest elevations as well as the east slope of the region where heavy snowfall combined with strong to extreme southwest winds during the storm.
Snowpack Summary
Significant variability in surface conditions is likely to be found in the region. In the Elk Valley and further west, a solid new surface melt freeze crust now likely caps the snowpack below about 2000 metres.Â
As a result of precipitation continuing as temperatures fell on Saturday night on the east slope of the range, roughly 20-30 cm of new snow, tapering with elevation, likely sits above a similar crust.Â
Above 2000 metres, suspected new snow amounts of 20-40 cm have been heavily impacted by strong to extreme southwest winds that affected the entire region. This new snow overlies previously wind affected surfaces.
A well consolidated mid-pack overlies a generally weak basal snowpack. The bottom 10-20 cm of the snowpack consists of facets and deteriorating crusts. While there has been little in the way of avalanche activity on this layer recently, it may be possible for a large load to trigger it in a shallow, rocky start zone.Â
Terrain and Travel
- Be alert to conditions that change with elevation, aspect and exposure to wind.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Problems
Wind Slabs
Our new snow at higher elevations has seen extensive wind redistribution as a result of strong to extreme southwest winds. Expect to find increasingly deep and reactive new wind slabs as you gain elevation on Sunday. More widespread (all aspects) storm slabs may be found in eastern parts of the region that saw snowfall continue as temperatures dropped on Saturday.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 3rd, 2020 5:00PM
