Avalanche Forecast
Issued: Jan 24th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
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Avalanche Canada
A cooling trend will reduce avalanche danger, but remain suspect of steep open slopes where it could be possible to trigger an avalanche on a buried weak layer.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
MONDAY NIGHT: Increasing cloud overnight as freezing level drops from 2000 to 800 m, strong wind from the southwest.
TUESDAY: Cloudy skies with some isolated flurries bringing trace amounts of snow, moderate wind from the west, freezing level around 800 m with treeline temperatures around -2 C.
WEDNESDAY: Clear skies except for a possibility of valley cloud, light wind from the west, an inversion forms with above freezing temperatures between 1200 and 2200 m.
THURSDAY: Clear skies except for a possibility of valley cloud, moderate wind from the southwest, freezing level around 1500 m.
Avalanche Summary
Over the weekend, there were a few human-triggered slab avalanches in the southern part of the region around Terrace. A few of these include size 1-1.5 persistent slab avalanches that occurred on a 30-50 cm deep surface hoar layer at treeline elevations. The photos of avalanches in this MIN report at Clague are good examples of the type of terrain this problem was found.
There were also several reports of loose wet avalanches on Sunday as temperatures began to warm up, and we expect a period of heightened activity also occurred during peak warming on Monday.
The melt-freeze pattern that will result from cool cloudy weather on Tuesday should help stabilize the snowpack, although we are uncertain whether the persistent slab above the surface hoar layer will remain reactive.
Snowpack Summary
A dramatic melt-freeze pattern will leave the snowpack capped with a hard crust. The crust will likely exist at all elevations, except below 1000 m where it should stay warm overnight. This temperature trend will create a generally strong settled snowpack, although there is a chance a 30-50 cm deep surface hoar layer could survive and remain reactive. This layer has been reported at treeline elevations in the Terrace area.
Terrain and Travel
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Persistent Slabs
While the overnight freeze after a big warmup should resolve most avalanche problems, it could still be possible to trigger an avalanche on a 30-50 cm deep surface hoar layer that has recently been reactive at treeline elevations near Terrace.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 25th, 2022 4:00PM
