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Archived

Avalanche Forecast

Jan 31st, 2022–Feb 1st, 2022
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
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

Regions: Lizard-Flathead.

The recent storm snow is expected to remain touchy on Tuesday, especially in wind loaded terrain and on steep slopes where it overlies surface hoar or a crust. 

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Unsettled conditions are expected on Tuesday as Arctic air shifts southward. 

Monday Night: Partly cloudy, light variable wind, treeline temperature dropping to around -12 C°.

Tuesday: Mainly cloudy with snow flurries up to 5 cm, light to moderate wind shifting to the NE, treeline high around -10 C°.

Wednesday: A mix of sun and cloud, light variable wind, treeline high around -15 C°.

Thursday: A mix of sun and cloud, light to moderate variable wind, treeline high around -8 C°.

Avalanche Summary

An early report from Monday shows explosives triggering numerous size 2 storm slabs which were releasing down 20-30 cm and propagating widely. On Sunday, a natural size 1 cornice release was reported failing overnight during strong winds. 

Snowpack Summary

Up to 25 cm of new snow has buried a highly variable snow surface which consists of wind affected surfaces in exposed high elevation terrain, a melt freeze crust at lower elevations and on solar aspects extending into the alpine, and/or widespread surface hoar in sheltered areas which is typically 10-20 mm but as big as 30 mm in places. 

The widespread January 18 rain crust is now down around 40-50 cm but has not been creating an avalanche problem recently. The midpack is strong and well-consolidated above the early December facet/crust layer which is now down 100-200 cm. This layer has been dormant recently and is not currently a concern for the region but could still be a problem in the future. See the most recent forecaster blog for more details on this layer. 

Terrain and Travel

  • Be especially cautious as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

Avalanche Problems

Wind Slabs

The new snow is expected to be most reactive in wind loaded terrain, especially where it overlies surface hoar and/or a crust. The wind was recently blowing from the SW during the storm but is expected to switch directions on Tuesday and wind slabs may be possible on all aspects. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2