Avalanche Forecast
Issued: Jan 18th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
dsaly,
Avalanche Canada
Winds will impact any remaining loose snow, be wary of wind slabs. Dig down and investigate deeper layers in the snowpack before committing to big lines.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
MONDAY NIGHT - Clear with patchy cloud / Northeast wind, 10-20 km/h / Alpine low temperature near -8
TUESDAY - Cloudy with isolated flurries / Southwest wind, 30-60 km/h and increasing through day / Alpine high temperature near -4
WEDNESDAY - Cloudy with isolated flurries / Southwest wind, 20-50 km/h / Alpine high temperature near -7
THURSDAY - Sunny / Northeast wind, 10-15 km/h / Alpine high temperature near -9
Avalanche Summary
On Wednesday and Thursday, explosives triggered numerous avalanches up to size 2.5, including a size 2.5 persistent slab avalanche each day.
Overnight Tuesday and during the day Wednesday, a widespread natural avalanche cycle up to size 3 was reported, one of which was a size 2.5 persistent slab avalanche.
Over the past week, there have been several natural and persistent slab avalanches between size 2.5-3 reported in the region. These avalanches are continued reminders of the "low probability; high consequence" scenario that persistent slab problems often create.Â
Snowpack Summary
Strong winds have polished and pressed snow into hard slabs and sastrugi, and stripped windward slopes and exposed the previous surface crust. Soft pockets of redistributed snow may hide in sheltered areas. A melt-freeze crust covers surfaces up to 1800 m. Roughly 80-120 cm of snow is now sitting on (another) crust that extends up to 1900 m, at weak layer of surface hoar may persist at this interface.
The main feature we are monitoring in the snowpack is a layer of weak faceted snow over a hard melt-freeze crust found around 90-200 cm down. Recent sporadic, large, naturally triggered avalanches have occurred on this layer on large alpine slopes and were triggered by either smaller wind slab avalanches, or cornice falls. Dig down and investigate the deeper snowpack layers before committing to big terrain.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Be alert to conditions that change with elevation, aspect and exposure to wind.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Winds will move any snow left for transport. Hard wind slabs may be stubborn, however slabs will be dense and firm when triggered. Give cornices their space.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer lurks deep in the snowpack. Avalanches on this layer are becoming less likely, however they will be large and destructive if they do happen.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 19th, 2021 4:00PM
