Avalanche Forecast

Issued: Dec 7th, 2021 4:00PM

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

VIAC ahanna, VIAC

New snow and wind are forming fresh slabs. We have uncertainty around the reactivity of two near-surface crusts. Take a conservative approach and investigate the bond at these interfaces before stepping into more committing terrain. 

Summary

Confidence

Moderate - Uncertainty is due to limitations in the field data.

Weather Forecast

Tuesday night: New snow 10-20 cm. Strong westerly wind. Freezing leveldropping 1500- 800 m.

Wednesday: A mix of sun and cloud. Strong northwest wind. Treeline high temperatures around -5. Freezing level 700 m.

Thursday: A mix of sun and cloud. Moderate northwest wind. Treeline high temperatures around -4. Freezing level 700 m.

Friday: Snow starting 5-10 cm. Strong southwest wind. Treeline high temperatures around -1. Freezing level 1000 m.

Avalanche Summary

No recent reports.

Snowpack Summary

10-20 cm of overnight snow fell amid strong wind, likely loading deeper deposits into lee features at upper elevations. The new snow may sit over a thin crust that formed when 20-40 cm of recent snow warmed up on Tuesday. This recent snow may be sitting over a weak layer of surface hoar crystals or facets over a thick crust.

Recent indications of the region's snowpack suggest alpine depths around 150- 200 cm, depth tapering dramatically with elevation to about 40-80 cm at treeline. Below treeline is below threshold for avalanches.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Start with conservative lines and watch for clues of instability.
  • Closely monitor how the new snow is bonding to the crust.
  • Keep in mind the crust offers an excellent bed surface for avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs

New snow and wind are forming fresh slabs over a thin crust. Recent snow under this crust is well-settled and dense and may remain reactive where it sits over a weak layer of surface hoar on a thicker crust. You can dig down to investigate the bond at these interfaces.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1.5 - 2.5

Valid until: Dec 8th, 2021 4:00PM