Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Cooler weather and less solar input is expected on Saturday. Despite the arrival of spring, the snowpack remains weaker in this region. We remain wary of all steep alpine terrain on shaded aspects where crusts are absent.
Confidence
Moderate
Avalanche Summary
No new avalanches were observed or reported Friday. The field team noted active wind loading at upper elevations, and suspected reactive wind slab development in the alpine.
Snowpack Summary
10 cm of snow sits atop crusts on all aspects except north-facing alpine slopes. The integrity of the snowpack is based mostly upon the strength of the surface crust when it refreezes overnight (or doesn't). In areas with no surface crust, concern remains due to the weak basal facets, which have plagued the mid and base of the snowpack all winter. This makes most steep, alpine terrain in the shallow snowpack areas of BYK suspect, and we have lower confidence in this snowpack.
Weather Summary
A low-pressure system moving into the forecast region on Saturday is expected to bring precipitation, with snow accumulations of10 to 20 cm. At lower elevations, this may fall as rain. Ridge-top winds are expected to ease with light values from the SW, and temperatures at valley bottoms will hover around zero. By the end of the weekend, a clearing trend is expected, accompanied by rising temperatures.
Terrain and Travel Advice
- Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.
- Start your day early and be out of avalanche terrain during the heat of the day.
Avalanche Problems
Wind Slabs
Wind slabs have been reported at the ski hills recently. Strong winds Thursday night and light snow will add to this problem. Use caution when transitioning from solar aspects (with a crust) to northerly alpine aspects, where we suspect wind slab development to be the main concern.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
A slab up to 80 cm thick sits on the weak facetted lower snowpack. On all but high north aspects, recent sun crusts and the March 27 rain crust cap this slab, providing some security. Use caution in higher, thin snowpack areas or where these crusts are weak or breaking down with heating.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3