Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Watch for windslabs in the alpine. The upper snowpack is slowly becoming more supportive and allowing for better travel, however, the lower snowpack remains weak and unsupported. Conservative terrain choices are still a good idea.
Confidence
Moderate
Avalanche Summary
Sunshine ski hill reported some small skiier controlled avalanches in windloaded treeline terrain but otherwise no new avalanches observed or reported by sunshine, lake louise and Parks Canada forecasters in the Yoho Valley.
Snowpack Summary
Recent moderate to strong winds have created windslabs in the alpine. Some suncrust exists on steep solar at treeline and below. Below this, the upper snowpack contains weak layers at 10-30 cm deep (Jan. 4th) and 25-50 cm deep (Dec. 17th) that are generally not reactive. The Nov 16 deep persistent layer is down 40-90 cm and continues to produce sudden failures in snowpack tests. In areas west of the divide, these layers are generally deeper and more spread apart in the snowpack.
Weather Summary
A NW flow will bring windy conditions with broken skies and light flurries on Wednesday and Thursday. A cold front followed by an upslope and arctic air arrives on Friday.
Wed: Alpine winds strong from the NW. High temp ~ -4, low -12
Thurs: Alpine winds extreme from the NW. High temp ~ -4, low -8
Fri: 5-10 cm. Alpine winds light to moderate and switching to NW. Temps cooling to -15
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
Avalanche Problems
Deep Persistent Slabs
The lower snowpack is comprised of weak facets and depth hoar with the upper snowpack forming a 40 to 90 cm thick slab above. This weak basal layer is uniform across most of the forecast region and has been responsible for most of the larger avalanche activity this season.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2.5
Wind Slabs
Strong to extreme winds on Sunday night formed small wind slabs in immediate lee areas of the alpine. These have been reactive to skier triggering in steep terrain.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 1 - 1.5