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Avalanche Forecast

Archived

Feb 4th, 2023–Feb 5th, 2023

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 and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Glacier.

Recent snow and wind have created fresh storm slabs that are sensitive to human triggering at all elevations.

Practice good group management and be aware of other people above and below you.

Confidence

High

Avalanche Summary

Today's field team found reactive storm slabs in the top 40cm of snow up to size 1 while skiing tree line and below in the Hermit area.

A widespread natural avalanche cycle occurred overnight on Friday into early Saturday morning with numerous avalanches size 2-3.5 throughout the highway corridor.

On Friday skiers reported size 2 natural avalanches on the SE face of Ross Peak and Bruins Peak.

Snowpack Summary

30-60cm of accumulated storm snow and wind have formed a storm slab. Expect this slab to be deeper in wind-loaded areas.

The mid-snowpack is mainly rounded grains and strong.

The Nov 17 deep persistent layer is near the base of the snowpack and is mainly facetted with a decomposing crust in some locations.

Weather Summary

Sunday will be cloudy with isolated flurries with ~5cm of accumulation, an alpine high of -4 and 20-50km/hr Westerly winds.

5cm on Monday and 20cm on Tuesday with cooling temps and 20-55km/hr winds.

Terrain and Travel Advice

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.

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.