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Avalanche Forecast

Archived

Feb 4th, 2024–Feb 5th, 2024

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Ski conditions are slowly improving at upper elevations with some new snow and cooling temperatures.

Continue to use caution on larger slopes in the alpine and at treeline since our persistent avalanche problems have not left us.

Confidence

Moderate

Avalanche Summary

A few small loose dry sluffs up to size 1 were observed in steep terrain on Sunday, and some small isolated wind slabs up to size 1 from the new snow were found in immediate lee areas at local ski areas. Explosive control resulted in a couple of larger avalanches up to size 2.5 at Norquay failing on the persistent and deep persistent layers at treeline and above.

Snowpack Summary

5-15 cm of new snow has greatly improved the ski quality at upper elevations. This new snow sits on a recently formed crust, which is widespread at all elevations, except for north aspects above 2500 m. The cooling temperatures have improved the stability of the mid-pack, but the January persistent facet layers down 20-50 cm, and deep persistent facet and depth hoar layers at the base of the snowpack, are still present at treeline and above.

Weather Summary

Light snow will continue on Sunday night with accumulations up to 5 cm. This is followed by a clearing trend on Monday as light flurries give way to a few sunny breaks in the afternoon. Winds will be light from the SW. Treeline temperatures will be between -6°C and -10°C.

For more mountain weather click HERE.

Terrain and Travel Advice

  • Avoid areas where the snow feels stiff and/or slabby.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Closely monitor how the new snow is bonding to the crust.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.