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Avalanche Forecast

Archived

Jan 3rd, 2022–Jan 4th, 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 unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

North Rockies.

Continued strong northeasterly winds are expected to form reactive wind slabs in open terrain at all elevations.

The best and safest riding will be on wind-sheltered slopes that have soft snow without any slab properties. 

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

MONDAY NIGHT: Cloudy / Moderate northeast wind / Low of -37

TUESDAY: Mix of sun and cloud / Strong northeast wind / High of -29

WEDNESDAY: Mostly sunny / Moderate east wind / High of -29

THURSDAY: Increasing cloudiness with flurries; 3-5 cm / Moderate southwest wind / High of -20

Avalanche Summary

Several explosive triggered storm slab avalanches up to size 2.5 were reported in the alpine and treeline on Sunday.

Over 60 cm of new snow on Saturday night in the pine pass area formed reactive slabs; especially in wind affected terrain.

Snowpack Summary

Continued strong northeasterly winds are expected to form reactive wind slabs on lee features at all elevations.

Freshly formed wind slabs are most likely to be found on south and westerly aspects, but older wind slabs may be found on all aspects.

The Pine Pass area received over 60 cm of new snow Saturday night which combined with strong southwest winds to form touchy storm slabs reactive to human triggers.

Much of the rest of the region received 10-20 cm of snow and strong southwesterly winds which formed reactive wind slabs on lee features at treeline and above.

A weak layer of feathery surface hoar may be found around 20 to 50 cm deep. It is most likely found in sheltered terrain features in the lower alpine and treeline, or open features below treeline (e.g., cut blocks). We've only received a few reports of this layer, so it may be spotty in the region.

The base of the snowpack is composed of crusts and weak faceted grains, particularly in thin snowpack areas east of the divide. These deeply buried weak layers will create large, destructive avalanches if triggered. Avoid likely trigger spots such as steep, rocky slopes, with a shallow or thin to thick snowpack.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of highly variable recent wind loading patterns.
  • The best and safest riding will be on slopes that have soft snow without any slab properties.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Keep your guard up at lower elevations. Wind slab formation has been extensive.

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.