Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
It's a beautiful week to be outside in the national parks. Clear, sunny weather will continue and that means our main avalanche concern is daytime warming with the sun impacting the snow. This year, large, deep avalanches always feel possible and heat can be a trigger.
Confidence
High
Avalanche Summary
There was a late-day loose wet avalanche cycle on Sunday, with temperatures reaching up to 11 degrees in the valley bottom. As of 4 pm on Monday, no new avalanches have been observed. We continue to expect deep persistent avalanches with almost any change in the weather, but so far this week no significant new ones have been reported.
Snowpack Summary
Above 1600 m the surface is 10-20 cm of soft, settled snow with minimal wind effect. Suncrusts are forming on steep solar slopes and are more widespread below 1400 m. The middle of the snowpack holds several crust layers that continue to produce avalanches, and the base of the snowpack is very weak depth hoar in almost all areas.
Weather Summary
A ridge of high pressure is dominating the weather picture until mid-week. Expect a few clouds in southern areas, but otherwise clear skies, light winds and freezing levels reaching 1800 m. Expect the sun to pack quite a punch in sheltered areas.
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.
Avalanche Problems
Deep Persistent Slabs
The weak depth hoar at the bottom of the snowpack inspires little confidence. Multiple parties have remotely triggered large slabs from thin areas in the snowpack. Give careful consideration to the slopes overhead as large avalanches may run well into the runout zone or into lower-angle terrain. Avoid big terrain features and be especially cautious in thin or rocky areas, where triggering is more likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 4
Persistent Slabs
Three persistent weak layers formed in January are down 40-110 cm. Buried sun crusts on steep solar slopes present the greatest concern for triggering, however, weak facets and isolated surface hoar can be found on the same interfaces on shaded aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3
Loose Wet
Clear skies and sunshine will produce wet avalanches on sun-exposed slopes late in the day. Rocky areas often increase this heating and low elevations may also be susceptible to this problem on Tuesday.
Aspects: South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1.5