Avalanche Forecast
Issued: Jan 21st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
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Avalanche Canada
Watch for slopes where thick deposits of new snow have accumulated, especially in wind-affected terrain.
Summary
Confidence
Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region.
Weather Forecast
TUESDAY NIGHT: 20-30 cm of snow in the southern part of the region and 5-15 cm in the northern part of the region, moderate wind from the southwest, alpine temperatures drop to -5 C.
WEDNESDAY: Cloudy with isolated flurries and up to 10 cm of snow, light to moderate wind from the southwest, alpine high temperatures around -3 C.
THURSDAY: 5-15 cm of snow above 1600 m (rain below), strong wind from the southwest, alpine high temperatures around -1 C.
FRIDAY: Another 5-15 cm of snow, moderate wind from the southwest, alpine high temperatures around -3 C.
Avalanche Summary
Recent storms resulted in several small (size 1) naturally-triggered slab avalanches in the northern part of the region on Sunday and Monday. Wet loose avalanches were reported around the Coquihalla over the same period.
Snowpack Summary
New snow is accumulating above wet and crusty interfaces after warm temperatures reached treeline elevations on Sunday. With strong southwest wind, expect scoured windward slopes in the alpine and thick wind slab deposits in lee terrain.
There are currently no concerns about deep weaknesses in the snowpack near Coquihalla summit and elsewhere in the south of the region. In the northern half of the region (e.g. Duffey, Hurley), there are several layers of concern. One is a weak layer of surface hoar buried about 100 cm deep that professionals are tracking at treeline and below on shaded aspects in sheltered areas. The other is weak faceted grains and crusts near the bottom of the snowpack, that is most likely to be triggered in shallow rocky start zones.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Storm Slabs
Recent snow and wind has left storm slabs sensitive to human triggering. Expect the depth and reactivity of slabs to greatly increase with elevation and exposure to wind.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Two layers that cause concern in the northern part of the region include:
- A 100 cm deep weak layer of surface hoar layer found around treeline elevations in sheltered areas. It may still be triggered by a person in steep, sheltered openings around treeline.
- A weak layer near the bottom of the snowpack which continues to produce sporadic very large avalanches. This layer is most likely to be triggered in steep, thin, rocky areas in the alpine or upper treeline.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 22nd, 2020 4:00PM
