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Avalanche Forecast

Archived

Feb 5th, 2023–Feb 6th, 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 and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Glacier.

Continuous snowfall and moderate winds will keep feeding the storm slab problem. Avoid committing avalanche terrain and allow the storm slab to stabilize.

The best snow quality is found at tree line and below.

Confidence

High

Avalanche Summary

Storm slabs at tree line and below were less reactive on Sunday as many happy backcountry users shredded deep pow. No new reports or observations of avalanches, but visibility was poor.

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

Snowpack Summary

30-50cm of settling storm snow over the last few days and wind has formed storm slabs. Expect this slab to be deeper in wind-loaded areas.

The mid-snowpack is mainly rounded grains.

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

Weather Summary

Mainly cloudy for Monday with snow accumulations up to 5cm by the evening. Ridgetop winds will be SouthWest 20-50km/hr with an alpine high of -8. Freezing level will be ~1000m.

A storm front approaches Monday evening into Tuesday with 30cm of snow and another 10-15cm by Wednesday morning.

More snow on Friday as well!

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.