Avalanche Forecast
Issued: Jan 7th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
dsaly,
Avalanche Canada
Storm stabs may continue to be reactive to skiers. The most reactive deposits will be around steep and convex features in open terrain, or anywhere wind encourages slabs to form.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather. Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.
Weather Forecast
Friday night: Snowfall tapering overnight, 5-10 cm with the far south of the region possibly accumulating upwards of 20 cm overnight. Strong SW wind. Treeline high around -16 °C.
Saturday: Mostly cloudy with isolated flurries, up to 5 cm. Moderate SW wind. Treeline high around -8 °C.
Sunday: A mix of sun and cloud. Moderate W wind. Increasing temperatures with a treeline high around -4 °C.
Monday: Cloudy with sunny breaks. Moderate SW wind. Treeline high around -4 °C.
Avalanche Summary
On Friday, explosives triggered storm slabs to size 2.5, and skiers triggered avalanches to size 2.
Evidence of a natural storm slab avalanche cycle size 2-2.5 was observed on NE aspects Wednesday and Thursday, likely having run during the storm earlier in the week.Â
On Monday and Tuesday, storm slabs were reactive to explosive up to size 2 and ski cuts produced storm slabs and loose dry avalanches up to size 1. By Wednesday, explosive results were limited to size 1 loose dry.
On Sunday, a size 2.5 persistent slab avalanche was triggered on an E aspect at treeline. This avalanche is detailed in a MIN post and features in our latest blog post, Photos of recent persistent slab avalanches in the southern interior.
Snowpack Summary
Upwards of 40 cm new snow accumulated by the end of Friday with warming temperatures. In open terrain and upper elevations, wind developed more reactive deposits formed around lee and convex features.
An accumulated total of 40-70 cm of new and recent snow now sits over variable and potentially weak snow surfaces including widespread facets, wind affected snow, and/or surface hoar in sheltered areas, which may make for a weak bond at this interface.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 90-200 cm. Activity on this layer has been sporadic, the most recent persistent slab avalanche in the region was on January 2. 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
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- 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.
Problems
Storm Slabs
Strong SW winds Friday with snowfall built fresh storm with more reactive and deeper deposits in leeward terrain. The new and recent snow may overlie a weak interface which could result in deeper and touchier than expected storm slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A persistent slab problem formed by a crust down 90-200 cm has created a low likelihood, high consequence scenario that is difficult to forecast. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 8th, 2022 4:00PM
