Avalanche Forecast
Issued: Dec 15th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
rbuhler,
Avalanche Canada
New wind slab formation is expected on Thursday as the wind shifts to a northwest direction. Given the recent shifting wind directions, reactive slabs should be expected on all aspects in exposed terrain.
Summary
Confidence
Weather Forecast
A weak upper trough is expected to cross the region on Wednesday night bringing light snowfall to the south of the region. The Arctic high pressure continues to influence the region on Thursday and Friday before a relative weak storm system reaches the region on Saturday.
Wednesday Overnight: Light snowfall 2-6 cm, moderate to strong NW winds, treeline temperature around -18 °C.
Thursday: Mostly sunny, moderate to strong NW winds, treeline high around -20 °C.
Friday: A mix of sun and cloud, moderate to strong SW-W winds, treeline high around -18 °C.
Saturday: Light snowfall, moderate to strong S-SW winds, treeline high around -12 °C.
Avalanche Summary
No new avalanches were reported on Tuesday. On Monday, a natural wind slab avalanche cycle up to size 2.5 was reported on SW-W aspects near Pine Pass in response to strong NE-E winds.
On Thursday, new wind slabs are expected to develop in response to the forecast strong NW winds. In the parts of the region which had strong outflow winds on Monday, lingering wind slabs are likely still reactive. Given the shifting wind directions, wind slabs should be expected on all aspects in exposed terrain.
Snowpack Summary
On Friday and Saturday, 20-30 cm of new snow was reported along with strong winds from the southwest which formed highly reactive slabs in wind exposed terrain, primarily on north and east aspects. On Monday, the wind switched directions and formed new wind slabs on south and west aspects. Forecast strong NW wind on Thursday is expected to develop new wind slabs.
The mid and lower snowpack likely contains of a series of early season crusts which may had undergone some faceting. In the deeper snowpack areas of the region, these layers generally appear to have stabilized and gone dormant but they still may be reactive in isolated areas, especially places with a shallow snowpack. Below around 1500 m elevation, the late-November crust is typically found down around 40 cm but generally appears to be unreactive.
Snowpack depth at treeline typically ranges from 50-250 cm, with the shallower value mainly on the eastern side of the range. The alpine snowpack typically ranges from 150-250 cm.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Wind Slabs
New wind slab formation is expected on Thursday as a result of the forecast strong winds from the NW. Reactive wind slabs from the strong outflow winds on Monday and Tuesday also remain a concern, especially on south and west aspects. Given the shifting nature of the recent winds, wind slabs should be expected on all aspects in exposed terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 16th, 2021 4:00PM
