Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Strong solar inputs Tuesday will weaken the snowpack on southerly aspects. Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Confidence
Moderate
Avalanche Summary
Recent storm snow has been producing loose dry avalanches on steep terrain in the alpine. In addition, one new natural size 3 deep persistent slab was observed on the east side of HWY 93N Monday
On Saturday, two skier-triggered avalanches were reported. One on Massive Mountain and the other near Observation Sub Peak. These show that human triggering of various buried layers is still possible.
Snowpack Summary
5-20 cm of storm snow sits over buried temperature crusts to 1500 m, sun crusts to ridgetop on solar aspects, and facets on shaded slopes. The midpack in this area has several crust and facet layers 30-110 cm down, that remain a concern in steep terrain. The bottom of the snowpack consists of weak basal facets in many areas, with sudden test failures still occurring.
Weather Summary
A ridge of high pressure will bring clear skies to the region. Overnight alpine temps for Monday and Tuesday will be near -20 with daytime highs climbing to 0 at 2000m. Winds will remain light to moderate. Though temps will be cold overnight, strong solar inputs throughout the day will likely cause the upper snowpack to deteriorate.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Cornices become weak with daytime heating or solar exposure.
Avalanche Problems
Deep Persistent Slabs
The lower snowpack consists of several weak layers that remain a concern. A combination of basal facets, and crusts are still possible to trigger. Give careful consideration to overhead hazard as large avalanches may run into lower-angle terrain. Avoid big steep terrain features and places where large triggers could impact the slopes below. Be cautious in thin or rocky areas, where triggering the basal weakness is more likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 3.5
Loose Wet
Strong solar inputs and upto 20cm of recent storm snow will likely produce loose wet avalanches on Southerly aspects. Pinwheeling and melting snow near rock are good indicators that the snowpack is being affected by solar radiation.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2