Avalanche Forecast
Issued: Jan 25th, 2020 4:30PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
astclair,
Avalanche Canada
Triggering avalanches remains possible where strong winds have drifted the recent snow into slabs at higher elevations. Stay alert and monitor for these conditions if travelling in these areas.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Saturday night: Partly cloudy, scattered flurries with trace accumulations, strong southwest winds, alpine temperature -5 C, freezing level dropping to 500 m.
Sunday: Mostly cloudy, a trace of new snow, moderate southwest winds, alpine high temperature -3 C, freezing level around 500 m.
Monday: A trace of new snow. Moderate south to southwesterly winds. Alpine high -4 C. Freezing level around 500 m.
Avalanche Summary
A few small, human-triggered wind slab avalanches were reported on Friday. Earlier in the week, there were reports of storm slabs releasing naturally (see this MIN report).
Last weekend, a natural storm cycle was observed at treeline and below. Slabs were soft and thin but propagated widely resulting in avalanches up to size 2. They ran on the faceted interface buried January 17th.
There have been reports trickling in over the past month of natural persistent slab avalanches up to size 3 in the Bulkley Valley. These are thought to have been failing on the November crust/facet layer near the ground. The last reported activity at this interface was Monday January 13th.
Snowpack Summary
Southerly winds have formed fresh wind slabs with the 15-30 cm (up to 50 cm in the Howson area) of recent snow. These slabs sit on previously scoured surfaces from the arctic outflow winds. In wind sheltered areas at treeline and below, the recent snow sits on a layer of facets.
A layer of surface hoar now buried up to 1 m below the surface may also be found at treeline. A deep crust/facet layer lurks at the base of the snowpack. A couple of large avalanches are suspected to have run on this interface in the last few weeks. These larger avalanches have been specific to lee and cross-loaded features in the alpine.
Terrain and Travel
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
Problems
Wind Slabs
15-30 cm of recent snow has been blown into wind slabs on north through east aspect slopes in exposed areas. In sheltered areas, the recent snow sits over weak, sugary facets and will likely continue to be reactive to human triggering on this interface.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 26th, 2020 5:00PM
