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Avalanche Forecast

Archived

Jan 29th, 2023–Jan 30th, 2023

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

Regions

Glacier.

Wind slabs can be found in the alpine and at tree line. If triggered, they could step down to deeper layers.

Cold temperatures are adding to the risks of backcountry travel, bring warm layers and leave yourself extra time to get out safely at the end of the day.

Confidence

Moderate

Avalanche Summary

Several skier-triggered sz 1-1.5 avalanches were reported over the last few days on Avalanche Crest, Hermit Slide path, and Swiss Couloir.

A natural cornice failure triggered a size 3 deep persistent slab on the SE slope of Grizzly Peak on Saturday.

Artillery control on Friday produced numerous size 2-2.5 and a few size 3 slab avalanches throughout the Park.

Snowpack Summary

Recent variable winds have created new wind slabs in the alpine and down into tree line.

The early Jan surface hoar is buried 40-70cm and is most prevalent at tree line. The November 17th facet weakness can still be found near the base of the snowpack in many areas.

Weather Summary

The ridge of high pressure will start to break down as a weak low pushes into the area. Expect a mix of sun and cloud on Monday, with 15-35km/hr Westerly winds and an alpine high of -15.

5cm of snow on Tuesday with gradually warming temperatures.

Terrain and Travel Advice

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

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.

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.