Banff Yoho & Kootenay National Park Avalanche Forecast

Issued: Nov 22nd, 2021 4:00PM

Mon Nov 22nd Current Conditions
Alpine Considerable Treeline Moderate Below Treeline Low
Tue Nov 23rd 2 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Low
Wed Nov 24th 3 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Low

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

Forecasters are still uncertain regarding the deep persistent slab problem on the Nov 5 layer. Carefully consider big terrain, especially in the alpine.

Summary

Weather Forecast

Thankfully, the strong westerly wind will subside overnight into the moderate range. A small amount of snow, in the neighborhood of 5 cm is expected Tuesday. Potentially up to 20cm is expected on Thursday. Temperatures will remain below zero in the valley, but slightly warmer than seasonal.

Snowpack Summary

5-25 cm of fresh snow in the last two days sits on a variety of surfaces: a rain crust below 2000m, a sun crust on steep solar aspects, windslabs in the alpine and exposed treeline areas and settled snow everywhere else. Melt/freeze crusts and/or facets lurk at the bottom of the snowpack. Snowpack depths at tree-line average 60-110 cm

Avalanche Summary

Both Lake Louise and Sunshine reported wind slabs in immediate alpine lee areas up to size 2. These were triggered though various ways, ski cutting, explosive and helicopter missions. No other avalanches were observed or reported.

Confidence

Due to the number and quality of field observations on Monday

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Reactive windslabs exist in the alpine and down into some tree-line locations. Intense loading was observed in alpine lee areas close to Banff on Monday afternoon.

  • Watch for surface cracking and stiffer surface layers of snow. Avoid wind loaded terrain.
  • Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine, Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

1.5 - 2.5

Although avalanches representing this problem are tapering off, forecasters are still receiving reports of them occurring. Although the latest reports are not larger than size 2, much uncertainty surrounding this problem still exists.

  • Be wary of slopes that did not previously avalanche.
  • Be aware of the potential for wide propagations due to the presence of hard windslabs.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Nov 23rd, 2021 4:00PM

Forecast Trend

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