Avalanche Forecast
Issued: Feb 21st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
mconlan,
Avalanche Canada
Avalanche danger remains elevated during this stormy period. Best to avoid alpine avalanche terrain and conservative travel techniques are warranted elsewhere.
Summary
Confidence
Moderate - Uncertainty is due to the track & intensity of the incoming weather system.
Weather Forecast
SUNDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, 60 km/h west wind, alpine temperature -7 C, freezing level 600 m.
MONDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 40 to 60 km/h west wind, alpine temperature -10 C, freezing level 500 m.
TUESDAY: Cloudy with snowfall and afternoon clearing, accumulation 2 to 5 cm, 30 to 40 km/h northwest wind, alpine temperature -10 C.
WEDNESDAY: Increasing clouds, 30 km/h southwest wind, alpine temperature -10 C.
Avalanche Summary
A natural avalanche cycle has likely occurred across the region from periods of rapid snow accumulation as well as rain at lower elevations. We may not see the evidence of the cycle until the storm dissipates and the skies clear.
Looking ahead, similar avalanche activity may continue into Monday as more snow and strong wind are forecast.
Snowpack Summary
30 to 50 cm of snow and strong south to southwest wind from the weekend has likely formed new storm and wind slabs. More snow and strong wind are forecast for Sunday night into Monday, building these slabs. The snow overlies hard wind-affected snow in exposed terrain and weak, faceted snow or surface hoar crystals in sheltered terrain, suggesting it may take some time for the new snow to bond to these surfaces.
A weak layer from late-January may be found around 60 to 100 cm deep. The weak layer consists of feathery surface hoar and it is most likely found in sheltered areas around treeline elevations. We haven't received reports of avalanches on this layer in some time, suggesting it may be bonding.
Two melt-freeze crust layers with associated weak faceted grains may be found in the lower snowpack. These layers are considered dormant given the lack of avalanche observations, however the most likely place to trigger them would be on slopes where the snowpack is thin.
Terrain and Travel
- Travel in alpine terrain is not recommended.
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
Around 30 to 50 cm of snow from the weekend has likely formed storm slabs in sheltered areas and been blown into wind slabs in exposed terrain. The snow may not bond well to underlying surfaces, meaning human-triggering of large avalanches could remain likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 22nd, 2021 4:00PM
