Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Human triggering remains a possibility. Conservative terrain choices will be important to sustain for the near future.
Avalanche control is being conducted on Mt. Whymper and the Simpson slide paths on Dec 29, 2022. These areas are closed during this time.
Confidence
Moderate
Avalanche Summary
Avalanche control on the Sunshine road produced results up to size 2.5. Typically the slabs were thin and didn't run far, but propagated widely. Lake Louise patrol managed to trigger a size 2.5 deep slab that scrubbed to the ground but received no results on similar adjacent features. Sunshine patrol also reported triggering deep persistent slabs up to size 2 with explosives, although they were only about 30cm deep.
Snowpack Summary
Windslabs remain in the alpine and some treeline areas. These slabs sit atop a weak layer of facets and surface hoar (Dec. 17th interface) and have been producing skier-triggered avalanches to size 2. Below this, the snowpack is generally facetted with the largest facets and depth hoar near the bottom. Snowpack depths at treeline range from 80-140 cm throughout the region.
Weather Summary
A slight cooling trend is expected on Thursday, with temperatures around -10 at the ridge and -5 at the valley. Very light snow is expected with accumulations of a few centimeters. The biggest factor will be the wind which will blow from the SW into the strong range at higher elevations.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Avalanche Problems
Wind Slabs
Windslabs remain in the alpine and exposed treeline locations. These slabs overlie weak, faceted snow that was on the surface during the prolonged deep freeze and human triggering is still possible.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
The whole snowpack is thin, weak and faceted, meaning that any avalanche starting in the upper layers could easily release on the ground. Avoid large alpine open slopes >30 degrees, especially where shallow and windswept and don't linger any longer than neccessary under overhead hazard.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Loose Dry
The snowpack below treeline is comprised almost entirely of weak, unconsolidated facets that sluff easily in very steep terrain. Steep gullies or chutes below treeline could develop larger than-expected sluffs, running further and with more force than usual. This problem is most prominent in thinner snowpack zones.
Aspects: All aspects.
Elevations: Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5