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
Expect to find deeper and more reactive deposits in lee terrain. Be especially mindful around steep, convex openings and ridge features.
Summary
Confidence
Weather Forecast
Friday night: Tapering flurries, up to 10 cm overnight. Strong decreasing to moderate W wind. Treeline low around -20 °C.
Saturday: Mostly cloudy with isolated flurries, up to 5 cm. Moderate to strong SW wind. Treeline high around -8 °C.
Sunday: A mix of sun and cloud. Moderate SW wind. Treeline high around -4 °C.
Monday: Sunny. Moderate SW wind switching NW. Treeline high around -3 °C.
Avalanche Summary
Few avalanches were reported on Thursday, however a natural avalanche cycle likely occurred sometime between Thursday and Friday with rapid loading of new snow.
On Wednesday, evidence of a natural storm slab avalanche cycle size 1-2 was observed, likely having run during the storm earlier in the week. Wind slabs continued to be reactive near Invermere into Tuesday, up to size 2. By Wednesday, avalanche activity was predominantly loose dry entraining mass to size 1.5-2.
On Tuesday just east of the region in the Rockies near Invermere, a size 3.5 (very large) persistent slab avalanche was triggered remotely by a skier on an alpine ridgetop. The resulting crown was 2-3 m deep and the avalanche ran about 1 km to the valley bottom. More details in this MIN report. This and other notable persistent slab avalanches in neighboring regions feature in our latest blog, Photos of recent persistent slab avalanches in the southern interior.
Snowpack Summary
20-50 cm of new snow accumulated by the end of Friday was accompanied by southwesterly wind and warming temperatures. An accumulated total of 40-80 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 up to 3 mm in sheltered areas.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 70-150 cm. Activity on this layer has been sporadic. It has generally been triggered on steep, rocky slopes, with a shallow or thin-to-thick snowpack. 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 deep persistent slab.
Problems
Storm Slabs
Southeasterly wind during the most recent storm produced deeper and more reactive deposits in lee features. Be especially mindful around steep and convex openings in the trees and ridge features in the alpine. The new and recent snow may overlie a weak interface which could result in deeper and touchier than expected slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A persistent slab problem formed by a crust down 70-150 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. Smaller storm slabs or wind slabs have the potential to step down to a deeper weak layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 8th, 2022 4:00PM
