Avalanche Forecast

Issued: Nov 29th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Watch for fresh storm slab building throughout the morning and as it gets tickled by the sun in the afternoon. We expect storm slabs to be most reactive in wind loaded lees at upper elevations, and on south aspects where the new snow may sit on a thin melt-freeze crust.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations. Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

Sunday night: 15-20 cm new snow, strong southwest wind, freezing level 1000 to 1200 m.

Monday: 5-15 cm new snow, then clearing in the afternoon. Moderate to strong northwest wind, freezing level 900 m.

Tuesday: Clear, light northwest wind, freezing level spiking to 3200 m.

Wednesday: Clear, moderate wind, freezing level 3200 m.

Avalanche Summary

Natural size 2 wind slab avalanches were observed in some of the higher elevation terrain (above 1900 m) in the north of the region.

Monday we're expecting storm snow avalanches size 1-2 especially in lee features where wind deposits fatter pockets of snow, or on wind-sheltered south aspects where the new snow may be falling on a thin melt-freeze crust.

Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything (or don't) while out in the field, please consider sharing via the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!

Snowpack Summary

20-30 cm of new snow falls ontop of wind affected surfaces at upper elevations and a thin melt-freeze crust on south aspects. Moderate to strong southwest winds will likely form fat pockets of reactive storm slab in lee features.

As the freezing level drops Monday, we might see the snow line creep down below where it currently sits at 900 m. Snowpack depth rapidly changes with elevation. The snowpack rapidly jumps to around 100 cm deep above 1000 m and between 150 to 200 cm near the mountain tops.

Check out this awesome conditions update from North Shore Rescue from Friday.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Give the new snow time to settle and stabilize before pushing into bigger terrain.
  • Be cautious of buried obstacles especially below treeline.

Problems

Storm Slabs

An icon showing Storm Slabs

New snow and wind are building fresh storm slabs throughout the morning. A touch of sun in the afternoon may keep them extra sensitive. Be especially cautious where wind deposits fat pockets of snow in lee features, and on south aspects where the new snow may sit on a thin melt-freeze crust.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Nov 30th, 2020 4:00PM

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