Avalanche Forecast

Issued: Nov 30th, 2021 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Loose Wet.

Avalanche Canada ahanna, Avalanche Canada

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Avalanche danger will increase through the day Wednesday. Avoid all avalanche terrain including low elevation runout zones during this period of heavy loading from new snow, wind, and rain.

Summary

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

Tuesday night: Flurries, 3-8 cm. Strong southwest wind. Freezing level rising 2000 to 2400 m by morning.

Wednesday: 10-25 cm wet snow, rain below 2000 m. Strong southwest wind. Freezing level 2400 m.

Thursday: 5-10 cm overnight then clearing. Moderate westerly wind. Freezing level dropping 2000 to 1700 m.

Friday: Mostly sunny. Light wind. Freezing level valley bottom.

Avalanche Summary

We are expecting a widespread natural avalanche cycle to accompany Wednesday's storm.

Neighboring Kananaskis Country reported a widespread natural avalanche cycle up to size 3 running full path on Sunday as well as a few naturals up to size 2 on Monday. Several of these large avalanches stepped down to a buried crust.

Reports in the region remain limited. If you go out in the mountains, please share your observations and/or photos on the Mountain Information Network

Snowpack Summary

Heavy amounts of wet snow in the alpine accumulate over wind pressed surfaces while rain soaks the snowpack treeline and below.

Two crusts are found in the snowpack: the mid-November rain crust buried 20-30 cm and reported up to 2100 m, and a crust from early November found at the bottom of the snowpack up to 2300 m, this crust is being to break down and facet. Heavy loading by the current storm will answer our questions about the potential for failure at this layer.

Snowpack depths range from 40-150 cm at treeline elevations. Higher elevations may hold a deeper snowpack, but also be more heavily impacted from recent winds. Snowpack depths decrease rapidly below 1900 m.

Early season hazards are very real right now, be wary of thin/shallow snowpacks, rocks, stumps, creeks, and other sharks hidden under fresh snow.

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

Problems

Storm Slabs

An icon showing Storm Slabs

Storm slab size and sensitivity to triggering will increase at upper elevations as the storm progresses through the day Wednesday. 

There may be potential for storm slab avalanches to step down to a buried crust, producing very large avalanches that could run to below treeline.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Almost Certain

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet

Loose wet avalanches will become increasingly likely as heavy rainfall soaks the snowpack treeline and below.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Very Likely

Expected Size

1.5 - 2.5

Valid until: Dec 1st, 2021 4:00PM