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Archived

Avalanche Forecast

Nov 24th, 2020–Nov 25th, 2020
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
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: Banff Yoho Kootenay.

Some new snow and wind may bump up the avalanche danger for Wednesday. Watch locally for snow amounts and wind effect. There is uncertainty as to what will make the Nov. 5 crust/facet layers become reactive.

Weather Forecast

Strong to Extreme winds will continue overnight into Wednesday, then decrease to the moderate range in the alpine. Expect 5-15cm at higher elevations along the divide and West, with less East of the divide. Temperatures will be in the -6 to -8C range at valley bottom and -12 to -15C at 3000m.

Snowpack Summary

Wind slabs present at treeline and above from W-SW winds. At treeline 20-50 cm of storm snow sits over a layer of preserved stellars. The Nov. 5 facet/crust combo is down 50-80 cm and producing variable test results from easy to hard. The Nov crust extends up to 2500 m on N aspects and higher on solar aspects. Snow depths at treeline are 50-130 cm.

Avalanche Summary

Ski hills reporting small wind slabs with explosive control Tuesday. A slide above Sacre Bleu on Mt. Rundle was observed as well, but hard to tell what the trigger was.

Confidence

Forecast snowfall amounts are uncertain on Wednesday

Avalanche Problems

Wind Slabs

Continued winds and some new snow will create wind slabs on lee features. Watch locally for their development.

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The deeper Nov.5 crust has facets growing above and below it, and exists up to 2500m on shady aspects, and higher on solar aspects. Where there is a dense slab overlying this layer, it remains a concern, and likely will be for the foreseeable future.

  • Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2.5