Avalanche Forecast
Issued: Dec 13th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
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Avalanche Canada
Heightened avalanche conditions exist on wind loaded slopes at upper elevations.
Summary
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.
Weather Forecast
A weak frontal system arrives on Tuesday evening.
SUNDAY NIGHT: Cloudy with a trace of snow, light west wind, low temperatures around -10 C.
MONDAY: Cloudy with some light flurries, light west wind, high temperatures around -8 C.
TUESDAY: Flurries throughout the day bring up to 5 cm of snow, moderate southwest wind, high temperatures around -6 C.
WEDNESDAY: Another 5 cm of snow overnight then some clearing in the afternoon, moderate west wind, high temperatures around -6 C.
Avalanche Summary
Over the past few days there have been a few reports of small avalanches above the recently buried surface hoar and crust layers. These include several dry loose avalanches in steep terrain and a size 1 skier triggered avalanches in Glacier National Park (see the photo in this MIN report). While these avalanches have limited destructive potential, we anticipate this developing into a more concerning problem when more snow arrives.
Snowpack Summary
While there is a lot of variability in surface conditions across the region, the message is similar everywhere: assess the bond of recent snow to crusts, especially if more than 20 cm of snow is present. Most parts of the region only have 10-20 cm of snow sitting above crusts. But in areas without crusts near the surface, this snow may sit above a preserved surface hoar layer. This is most likely at higher elevations in the Selkirks.
A buried rain crust can be found in the lower snowpack (50-150 cm deep) with some reports of weak snow around this crust. While we have not seen recent avalanches on this layer, it continues to produce occasional results in snowpack tests. It may be reactive to human triggers on shallow rocky slopes in the alpine or alpine-like features at treeline.
Terrain and Travel
- Investigate the bond of the recent snow before committing to your line.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
Problems
Wind Slabs
10-30 cm of snow from last week may be blown into unstable slabs. In certain areas this snow may be poorly bonded to underlying layers of surface hoar and/or crusts. This is most likely a problem at treeline and alpine elevations in areas that received more than 20 cm of snow in the recent storm.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 14th, 2020 4:00PM
