Avalanche Forecast

Archived

Dec 28th, 2022–Dec 29th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

The highway is open to Parkers Summer for recreational use.

Avalanche Control on Highway 93 was stymied by poor visibility Wednesday. Anticipating full opening Thursday at 17:00.

Be very cautious in open areas where a stiffer slab will propagate widely. The few shots we could take showed a 4F soft slab, reactive to light loads, down 20 cm.

Confidence

Moderate

Avalanche Summary

Avalanche Control was delayed due to poor visibility. Observed natural activity is limited to the alpine. The few charges deployed today all produced storm slab results on low-elevation targets up to sz 1.5.

Snowpack Summary

20-30 cm of storm snow has developed into a soft slab over very airy facets. The storm interface is mostly made up of facets and small surface hoar making it quite reactive. Facets and depth hoar make up the deep persistent base, to ground. Snow height ranges from 50-120cm.

Weather Summary

Overnight Wednesday and through the day Thursday, the forecast calls for mainly cloudy skies with very light flurries. Light to Moderate winds from the southwest. Temperatures steady at -10.

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.