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Archived

Avalanche Forecast

Jan 31st, 2023–Feb 1st, 2023
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Glacier.

Accumulating storm snow is building into a surface slab, which could step down to the lingering persistent slabs.

Less visited areas in Glacier National Park may have more sensitive persistent weak layers, due to less skier/rider traffic cutting up the slabs.

Confidence

Moderate

Avalanche Summary

Isolated sz 2 natural avalanches were detected from Smart Peak, Mannix, and MacD Gully 6 overnight.

Several human-triggered sz 1-1.5 avalanches were reported over the weekend 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.

Snowpack Summary

15-20cm of storm snow sits atop old wind-affected surfaces in the alpine and treeline.

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

Weather Summary

Continuing flurries with moderate/strong winds aloft and a gradual warming to seasonal norms.

Wed: cloudy, flurries, 5cm snow, Alp high -9*C, light/moderate SW winds

Thurs: mix of sun and cloud, isolated flurries, Alp high -7*C, light/moderate SW winds

Terrain and Travel Advice

  • Loose avalanches may start small but they can grow and push you into dangerous terrain.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

Avalanche Problems

Storm Slabs

Low density storm snow, accompanied by moderate ridge-top winds, is forming soft slabs on variable wind-affected surfaces. Sensitivity to triggering will increase with wind spikes throughout the day.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

This layer has been most reactive around treeline, particularly in areas that have not seen significant skier traffic.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 3

Deep Persistent Slabs

Recently, a large cornice-triggered natural avalanche stepped down to this basal layer. Watch for steep, thin rocky areas where this layer could be activated.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2.5 - 4