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Archived

Avalanche Forecast

Dec 29th, 2020–Dec 30th, 2020
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
1: Low
The avalanche danger rating below treeline will be low
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: Glacier.

We currently have a complex snowpack with persistent weak layers that could produce high consequence avalanches if you were unlucky enough to trigger them.

Be particularly cautious on open slopes with a crust at the Dec. 7th weak interface.

Weather Forecast

High pressure will give stable weather for one more day. A frontal system arriving from the Northwest will give increasing wind and steady snowfall Wednesday.

Today: Mix of sun and cloud. Alpine High -8 C. Ridge wind light SW.

Tonight: Cloudy with isolated flurries. Alpine Low -10 C.

Wednesday: Snow (15cm). High -8 C. Ridge wind moderate-strong SW.

Snowpack Summary

Up to 25cm of recent snowfall is being stiffened into a slab in some wind exposed areas. This new snow covers spotty surface hoar in sheltered areas at and below treeline. Weak layers persist down 70-110cm (Dec 13 surface hoar), and 110-130+cm (Dec 7 crust/facte/surface hoar).  The Nov. 5th crust complex is near the base of the snowpack.

Avalanche Summary

There were MIN reports of skiers triggering loose dry avalanches up to size 2 in steep terrain, and one small storm slab in an immediate lee at treeline.

There was a natural size 2.5 storm slab from steep North facing terrain on Mt Macdonald.

Several very large avalanches last week failed on the early December crust, facet/surface hoar combo.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

Watch for pockets of storm slab in immediate lees Tuesday. Expect this problem to become more widespread and destructive with Wednesdays snow and wind.

  • Watch for stiffer feeling snow. Avoid areas that appear wind loaded.
  • Use safe ski cutting techniques to enter your line.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2.5

Loose Dry

Slough management is necessary on steeper, open slopes. Loose dry slides are gathering enough mass to push a skier or rider over, or even bury one in a terrain trap.

  • If triggered dry loose point releases can form deeper deposits in terrain traps.
  • Be careful of loose dry power sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

The Dec 7th and Dec 13t layers produced very large avalanches last week, up to size 4! One of these very large avalanches, from a South aspect at Treeline, had the Dec 7th interface as the failure plane which consisted of a crust with facets above.

  • Be wary of large open slopes that did not previously avalanche.
  • Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3.5