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Archived

Avalanche Forecast

Nov 15th, 2021–Nov 16th, 2021
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

An unprecedented dump (150+cm in 48hrs) for mid-Nov has dramatically changed the landscape. Storm slabs are prevalent at all elevations and aspects.

Travel cautiously for the next couple of days, observing how this huge load settles on the slopes.

Weather Forecast

An Arctic ridge will move into the region early Tues am, bringing cold temps and stable weather.

Tonight: Flurries, 6cm, Alpine high -13*C, mod/strong W winds

Tues: Cloudy w/ sun and isolated flurries, Alpine high -13*C, light/mod W winds

Wed: Cloudy w/ sunny periods, Alpine high -8*C, light SW winds

Thurs: Cloudy, Alpine high -8*C, light SW winds

Snowpack Summary

150+mm of precip in the past 48 hours has formed a remarkable storm slab! The new snow has fallen with moderate SW winds and mild temps. Snow depths have ballooned, with 1m at Rogers Pass, over 1.5m at tree-line, and 2+m in the Alpine. There are 2 crusts to date, the Nov 5th buried ~100cm and the Oct crust that lies near the base of the snowpack.

Avalanche Summary

Numerous large avalanches (sz 3-3.5) observed along the highway corridor, with many running down into valley bottoms.

Expect this natural avalanche cycle to slow on Tues with the end of the snowfall and cooling temps.

Confidence

Due to the number and quality of field observations

Avalanche Problems

Storm Slabs

In the past 48hrs, we received 100cm of snow at 1300m and 150+cm in the alpine. Warm temps and strong SW winds have helped form this load into a cohesive storm slab. This sits on a widespread rain crust that has been found high into the Alpine.

  • Use caution in alpine and open treeline lees. Recent snowfall has created storm slabs.
  • Avoid paths that have not avalanched recently.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3

Loose Dry

In the Alpine and upper Tree-line, expect fast-moving, loose, dry avalanches in steep, sheltered/confined terrain features.

  • Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2