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Archived

Avalanche Forecast

Nov 29th, 2020–Nov 30th, 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
1: Low
The avalanche danger rating below treeline will be low
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
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.

Widespread wind affect has increased slab cohesion and reduced the travel quality at and above treeline. Expect all areas exposed to wind transport to have more reactive slabs

Weather Forecast

High pressure continues for today with clear skies, light SW wind and a high of -7. Trace snow will start tonight and continue through the day tomorrow with cloudy skies, a high of -6 and a brief W wind spike in the evening. Tuesday brings a significant high pressure ridge forecast to hold clear skies for the week

Snowpack Summary

60 cm of storm snow sits over old snow and the Nov 23 surface hoar size 3. The surface hoar has been observed, rounding, at treeline in isolated areas but not found in other profiles. The Nov 5 crust is now between 90 and 140cm down which is within the triggerable range for skiers and snowboarders in some areas.

Avalanche Summary

A skier triggered sz 2 from Overlook yesterday had very wide propagation. Numerous natural avalanches sz 1.5 to 2.5 on all aspects in the hwy corridor and Connaught creek yesterday as well 3x sz 3s including Cheops N 4. A skier triggered sz 1.5 in Avalanche Crest and a 2.5 in Quartz this week failed on SH with wide propagation.

Confidence

The weather pattern is stable

Avalanche Problems

Wind Slabs

60cm of snow fell this week with strong SW winds. Slabs will be more reactive in open wind affected areas in the alpine and at treeline. In isolated areas this has been reactive in sheltered areas over a preserved surface hoar layer

  • Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.
  • Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1.5 - 2.5

Persistent Slabs

Steep planar slopes should be avoided, especially at treeline and into the lower alpine. Recent natural/human triggered avalanches, snowpack test and reports of whumphing indicate that this layer may still be triggered by the weight of a skier.

  • Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3