Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Increasing winds and snow will contribute to slab development into the start of the week.
Watch for fresh slabs over crusts on solar aspects as well as further development of the existing slabs on shaded slopes.
Confidence
Moderate
Avalanche Summary
Over the last couple of days some small thin, fresh windslabs and sluffs have been triggered in the surface snow in the alpine.
Friday and Saturday, loose wet avalanches were generated as the recent snow became wet in steep terrain over previous crusts.
The recent cool temperatures have temporarily slowed down the deeper avalanche activity.
Snowpack Summary
5-15 cm of recent snow is likely now capped by sun crusts. On north aspects this snow sits over dry snow above 2200m. Isolated wind slabs are found in the alpine, these will build, and wind effect will spread to treeline as winds increase.
In the mid-pack, the Feb 3 persistent layer (crust / facets) remains a concern in thin areas on northerly alpine aspects near 2300m and above where no crusts have formed to date. Below this, facets and depth hoar comprise the lower snowpack.
Monday5-15 cm of recent snow is now likely to have crusts on all but north aspects where it sits over dry snow above 2200m. Wind effect treeline and above
In the mid-pack, the Feb 3 persistent layer (crust/facet layer) remains a concern on northerly alpine aspects near 2300m and above where no crusts have formed to date.
Tuesday5-15 cm of recent snow is now likely to have crusts on all but north aspects where it sits over dry snow above 2200m. Wind effect treeline and above
In the mid-pack, the Feb 3 persistent layer (crust/facet layer) remains a concern on northerly alpine aspects near 2300m and above where no crusts have formed to date.
Weather Summary
Saturday Overnight: Winds increase: moderate to strong SW. Freezing Levels near 1500m. Snow begins as a cold front passes.
Sunday: Light snow accumulation: 5 cm. Freezing level to approx 1800m. Winds: west, strong.
Monday: Winds diminish, cloudy with some potential for flurries. Freezing levels rise to near 2000m. Clearing overnight.
Tuesday: Warming, freezing levels approaching 2500m.
Terrain and Travel Advice
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Avalanche Problems
Wind Slabs
Winds increase to strong SW overnight Saturday before shifting W as snow arrives Sunday.
Expect thicker slabs at higher elevations on north slopes and thinner new slabs to form over crusts on solar slopes. Sluffing out of extreme terrain should also be expected and may act to trigger these slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1.5
Persistent Slabs
Northern slopes in thin snowpack areas from the top of treeline remain a concern. While activity on this layer slowed down with cooling, the most recent activity was noted as resulting from cornice failures and smaller wind-generated events. All of these avalanches step down to the basal facets.
Aspects: North, North East, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3