Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
The past few days have seen a major avalanche cycle due to a crappy snowpack and mix of weather inputs—warm temperatures, rain, high freezing levels, and new snow in the forecast.
Give avalanche terrain a miss for now. There is uncertainty about what will happen in the short term, and the snowpack will take time to adjust.
Confidence
Moderate
Avalanche Summary
A widespread avalanche cycle throughout the region occurred on Wednesday and Thursday. Avalanches to size 3.5 started at all elevations and ran mainly to the tops of runouts, with some going to valley bottom. A notable on Thursday was the ice climb Masseys in Field, running for a second time in 2 days to the valley bottom.
Snowpack Summary
Freezing levels reached ~2800m for the second day in a row, accompanied by rain and snow. Precipitation totals since March 25 are 10-20mm of rain at lower elevations and unknown amounts of snow up high! A dense slab, 50-100 cm thick, sits atop persistent weak layers of facets. In Eastern areas, facets and depth hoar extend to the ground (see profiles below), whereas, in thicker regions west of the divide, the layer is thinner with a more settled lower snowpack.
Weather Summary
Freezing levels will drop to valley bottom Friday AM and rise to 2000m in the afternoon. Expect 10-30cm over the region by Friday night with light winds. See below for details.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices.
Avalanche Problems
Persistent Slabs
A 50-100 cm slab of dense snow now sits atop mid-pack facets and, in eastern areas, depth hoar to the ground. There has been a lot of activity on this layer, and where it hasn't avalanched, it will be prone to.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 2 - 3.5
Storm Slabs
20-30 cm of new snow is expected by Friday afternoon. We suspect storm slabs will form over the day, adding to previous slabs. Watch locally for their formation. If these form quickly, they could be touchy in the short term.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Loose Wet
The lower-elevation snowpack has a lot of moisture due to previous rain and warm temperatures. Temperatures are expected to drop on Friday, but it may take some time to lose that moisture.
Aspects: All aspects.
Elevations: Below Treeline.
Likelihood: Possible
Expected Size: 1 - 2