Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Human triggering of avalanches is almost certain right now, especially on Hwy 93 north around Bow Summit, where the snowpack almost doubled in 48 hours. Many reports of spooky conditions, whumphs, remote triggers and large avalanches with more snow coming on Thursday. Stay away from avalanche terrain, conditions are dangerous.
Confidence
High
Avalanche Summary
Poor visibility today, but natural avalanche activity continues, with a size 2.5 recorded outside the Sunshine boundary and another size 3 reported in Kananaskis Country. Fracture lines 300 - 500 meters wide. We don't have any reports from teams in the backcountry today. The photo below is from Mt Hector, several days ago but gives a sense of how wide the fracture line are.
Snowpack Summary
The recent storm dropped 25 cm (in Kootenay & Sunshine), 50 cm (Lake Louise), and 75+cm (Bow Summit). Strong southerly wind redistributed this snow creating slabs over suncrusts on steep south aspects or firm wind affected snow elsewhere. A persistent weak facet layer (Feb22/Jan 30 layer) is buried 40-100cm down.
In shallower eastern regions, the mid and lower snowpack is very weak with facets, while deeper western regions are more consolidated.
Weather Summary
The storm track continues this week, as another low-pressure system moves over our region bringing more snow on Thursday. Snow begins Thursday morning and we could see between 10-20 cm by the end of the day. This snow falls under temperatures from -4 to -6, and moderate winds from the SW.
Terrain and Travel Advice
- Make conservative terrain choices and avoid overhead hazard.
- Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Avalanche Problems
Storm Slabs
25-75 cm of storm snow since Saturday, and strong southerly winds, have created storm and wind slabs at all elevations. Greater amounts of snow fell in the northern forecast area (Bow Summit).
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1.5 - 3
Persistent Slabs
In many areas the storm snow has overloaded the persistent layers in the mid and and lower pack, resulting in very large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 2 - 3.5