Avalanche Forecast
Regions: Banff, East Side 93N, Kootenay, LLSA, Sunshine.
Great skiing continues!
Storm snow amounts over the past 48 hours range from 10 to 30 cm depending on the region and convective activity, with more snow in the south.
With broken skies forecast for Sunday, the sun could increase the hazard in the PM. Start and finish early.
The more sun, snow, and wind; the more the hazard will increase.
Confidence
Moderate
Avalanche Summary
A few small wind and storm slabs up to size 1.5 were reported during avalanche control at the local ski areas.
Natural avalanche activity was limited on Saturday, with some dry loose sluffing in steep terrain. There was evidence of a more widespread dry loose and storm slab cycle up to size 2 in the alpine during the storm.
In the last week, there were four size 2-3 avalanches that were remotely or accidentally triggered on northerly aspects in sub-alpine thin snowpack areas.
Snowpack Summary
Up to 35 cm of storm snow (depending on convective activity) over old sun crusts on solar aspects, with new solar crusts forming. On polar aspects this snow sits over a layer of stellars/spotty surface hoar crystals and is worth montioring.
Our main concern is shallow snowpack areas on northerly alpine aspects where the midpack is thinner/weaker, and triggering Feb 3 facet/crust layer and basal facets/depth hoar remains possible.
Deeper snowpack areas have few concerns.
Weather Summary
Saturday night and Sunday:
Freezing levels to valley bottom overnight. Scattered flurries taper off through the day Sunday, as an upper trough leaves the region. Freezing levels will rise above valley bottom to 1900 m. Light to moderate westerly ridgetop winds.
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Terrain and Travel Advice
- Be alert to conditions that change with elevation and sun exposure.
- Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
Avalanche Problems
Loose Wet
As we head into April the sun will come with more "punch". Sunny skies on Sunday may result in wet loose avalanches in the afternoon especially on steep solar aspects and in rocky terrain.
Recent storm snow could also form a cohesive storm slab and become reactive on buried crusts.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 2
Wind Slabs
Wind slabs may be present on ridgetop and cross-loaded features, with failures possible on the interface below the storm snow. Monitor this interface carefully in steep terrain.
Dry loose avalanches out of steep terrain could also present issues in confined terrain features.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
The Feb 3 crust/facet interface is down 70-110 cm. In shallow snowpack areas on northerly alpine aspects this layer remains sensitive to skiers, with remote triggering observed in several instances. All the recent avalanches that initiated on this layer stepped down to the basal facets / ground.
Aspects: North, North East, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3