Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
A return to winter with 10-20 cm of snow in the forecast will refresh the ski quality!
Watch for sluffing in steep terrain at all elevations.
Confidence
Moderate
Avalanche Summary
No new avalanches were observed or reported on Wednesday
Snowpack Summary
10-20 cm of new snow with moderate SW winds is creating windslabs in alpine lee terrain. This sits on widespread melt freeze crusts which exist everywhere except high north aspects (above 2100m). Below this, the Feb 3rd crust layer exists down ~ 50 -100 cm. Basal facets persist in thin snowpack areas and total snowpack depths range from 90-170 cm at treeline.
Weather Summary
A cold front is upon us and most areas should see 10-25 cm of new snow by Thursday AM. Winds will be light to moderate and temperatures will be in the -5 to -10 range.
The system gradually leaves the area on Friday and Saturday but expect to see some residual upslope precipitation (more snow on the east side of the range). Temperatures will cool to -5 to -15 and winds will be generally light.
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Terrain and Travel Advice
- Closely monitor how the new snow is bonding to the crust.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Avalanche Problems
Wind Slabs
10 -20 cm of new snow is forecasted to fall by Thursday morning with moderate southwest winds. This may create windslabs in alpine and isolated treeline lee features. These slabs overlie a buried melt freeze crust in many areas and will likely slide easily.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
The Feb 3 crust/facet interface is down 50-100 cm. We expect this layer to strengthen as colder temperatures penetrate the snowpack, but this may take a few days to play out. A big warm-up followed by a big cool-down is generally good for snow stability.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3
Deep Persistent Slabs
During the warm snap, many avalanches released on the ground resulting in large avalanches, most commonly in thin, steep, rocky terrain in the alpine. The incoming cooler temperatures will reduce the likelihood of triggering this problem, but the weak snow at the base of the snowpack remains.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5