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Archived

Avalanche Forecast

Nov 20th, 2020–Nov 21st, 2020
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

The persistent slab is reaching critical load for both human and natural triggering. Use caution when travelling through runouts

Weather Forecast

5cm new snow is forecast today with moderate westerly wind and freezing levels rising to 1000m. Another 10cm overnight with cooling temperatures will give way to a clear Saturday and Sunday with rising temperatures and wind shifting to the SW.

Snowpack Summary

Up to 70cm of storm snow has formed reactive slabs. The Nov 5th crust is now down 45cm below treeline and up to 1m in the alpine. It can be found, 8cm thick, up to 2500m on all aspects and higher on steep solar aspects. Facets above and below the crust are making this combo an active weak layer with all the recent load over it.

Avalanche Summary

Numerous size 2.5 - 3 avalanches occurred naturally throughout the day yesterday and overnight, initiating in the storm snow, with some stepping down to the Nov 5th crust/facet persistent slab. Field teams ski cut avalanches to size 2 yesterday and there were several Min reports this week of natural, and skier triggered avalanches.

Confidence

Avalanche Problems

Storm Slabs

Recent new snow, warm temperatures, and strong wind have created storm slabs in the alpine, and exposed areas of treeline. Natural avalanches are possible today and skier triggering remains likely, especially on steep unsupported terrain features.

  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
  • Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1.5 - 3

Persistent Slabs

MIN report from yesterday of skiers triggering storm slabs that stepped down to the Nov 5th crust. At lower elevations where the crust is shallower it is possible for skiers to directly trigger this layer.

  • 1011
  • New storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3