Avalanche Forecast
Issued: Feb 11th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Cornices and Loose Wet.
rbuhler,
Avalanche Canada
Warm and sunny conditions are keeping the danger elevated. Weak cornices and loose wet avalanches should expected during the heat of the afternoon.
The biggest concern remains a weak layer down 30-70 cm which is still capable of producing very large and destructive avalanches.
Summary
Confidence
Weather Forecast
A ridge of high pressure brings very warm and sunny conditions which are expected to persist until the end of Sunday. A temperature inversion is expected with cooler temperatures in the valleys.
Friday night: Clear, light N wind, freezing levels around 3000 m.
Saturday: Sunny, light variable wind, freezing levels around 3000 m.
Sunday: A mix of sun and cloud, light to moderate SW wind, freezing levels dropping to around 2500 m.
Monday: Light snow overnight and morning, sunny breaks in the afternoon, moderate variable wind, freezing levels 1000-1500 m.
Avalanche Summary
On Thursday, a natural cornice release was reported on a SE slope at 2100 m which triggered a small slab on the slope below. Some natural wind slab activity was also reported which likely occurred Wednesday night. Another natural cornice release was also reported as well as two loose wet avalanches.
Last weekend, several very large human-triggered avalanches occurred on the late-January persistent weak layer. This layer is now sitting dormant but there is serious concern that it is going to wake up with sun and very warm temperatures this weekend. The layer is down 30-70 cm so it is still in the prime depth for human-triggering. Cornice releases are also a major concern for triggering persistent slabs so give extra caution to overhead slopes which are exposed to cornices.
Snowpack Summary
A widespread surface crust was reported on Friday which appears to have broken down on steep sun-exposed slopes during the afternoon. Crust formation is expected to continue Friday night with clear skies in the forecast but will likely break down again on steep sun-exposed slopes on Saturday afternoon. Prior to the warming and sun, strong winds had caused extensive wind effect and wind slab formation in exposed terrain at higher elevations.
The problematic late-January crust/facet interface is now buried down 30 to 70 cm. This layer is most reactive between 1700 m and 2000 m, but is present above and below this elevation band and may still be reactive. It had produced several human and remote triggered avalanches last weekend. Although this layer is widespread, its exact composition and reactivity has significant spatial variability. In sheltered terrain at treeline and just above, surface hoar may sit on the crust which has the potential to further increase the reactivity of this interface.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of buried weak layers.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
- Extra caution is needed around cornices under the current conditions.
- Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
Problems
Persistent Slabs
30-70 cm of snow sits over a crust/facet weak layer combination that is still possible to human trigger. Recent observations demonstrate the potential for this problem to be triggered remotely and to propagate far and wide if triggered. This layer is most reactive between 1700 and 2000 m but should be expected above and below this elevation band.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are expected to become weak with daytime warming and solar radiation.
There may still be old wind slabs lingering in the alpine but the likelihood of triggering these old slabs continues to diminish with each day of the ongoing warming.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
Loose wet avalanches should be expected on steep, sun exposed slopes during the heat of the afternoon.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 12th, 2022 4:00PM
