Avalanche Forecast
Issued: Jan 13th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Cornices and Persistent Slabs.
jfloyer,
Avalanche Canada
Warm temperatures and solar radiation produced very large avalanches on Thursday. Cooler temps and low elevation cloud on Friday should improve things at treeline and below, but in the alpine, warm temperatures and more sunshine will prolong the danger.
Summary
Confidence
Moderate - Uncertainty is due to rapidly fluctuating freezing levels. Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.
Weather Forecast
Thursday night: Gradually increasing cloud. Freezing level falling to around 1200 m. Â
Friday: Cloudy up to around 2500 m elevation, which may be thick enough to give some very light precipitation. A layer of warm air (possibly above freezing) will exist above around 2500 m. winds light in the morning, increasing to moderate southwesterly in the afternoon.
Saturday: Mostly cloudy, up to 3 cm new snow, moderate southwesterly winds, treeline high around -2 °C, freezing level around 1400 m.
Sunday: Mostly dry with some clear spells. Moderate southwesterly winds. Freezing level around 1200 m.Â
Avalanche Summary
Three very large avalanches were reported from this region on Thursday. The avalanches appear to have failed on the early December crust and showed wide propagation. They occurred on southwest to southeast aspects and were naturally triggered in response to rising temperatures and solar radiation.
These avalanches follow a previous sporadic pattern of very large avalanches that have been reported from this region and neighbouring regions over the last couple of weeks.Â
Snowpack Summary
Recent new snow has settled fast and become dense due to warm temperatures. This snow sits on a variety of old surfaces, including soft snow in sheltered areas and wind slabs in exposed and open areas which formed over the past few days.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 100-270 cm. This layer appeared to "wake up" in response to warm temperatures and solar radiation on Thursday Jan 13, when at least three very large avalanches were reported on this layer. This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Avoid freshly wind loaded terrain features.
Problems
Wind Slabs
Exposed slopes at higher elevations may harbour wind slabs that could be reactive in exposed areas.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Cornices are reactive to human traffic with the warm temperatures and natural cornice falls become more likely. Large cornice falls are dangerous on their own.
A failed cornice can trigger buried persistent weak layers and result in very large and destructive avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A persistent slab problem formed by a crust down 100-270 cm has created a low likelihood, high consequence scenario that is difficult to forecast. There has been an increase of avalanche reports on this layer recently. It is uncertain how the forecast warm temperatures will affect the snowpack and if we will see more activity on this layer during the warm period.
Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack. Large additional loads like small avalanches or cornice falls can trigger deeper weak layers. The same feature or path can slide repeatedly when the persistent weak layer is reloaded with new snow.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 14th, 2022 4:00PM
