Avalanche Forecast

Issued: Jan 31st, 2022 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs.

Avalanche Canada rbuhler, Avalanche Canada

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South Rockies.

Recently formed wind slabs are expected to remain touchy on Tuesday, especially where they overlie surface hoar or a crust. Loose dry avalanches should be expected on steep slopes.

Summary

Confidence

Low - 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 to moderate NW wind, treeline temperature dropping to around -14 C°.

Tuesday: Mainly cloudy with snow flurries up to 5 cm, light to moderate NW wind, treeline high around -14 C°.

Wednesday: Mainly sunny, light variable wind, treeline high around -16 C°.

Thursday: Mainly sunny, light to moderate variable wind, treeline high around -8 C°.

Avalanche Summary

An early report on Monday shows ski cutting and explosives triggering small storm slabs and loose dry avalanches. Neighbouring regions were seeing some natural wind slabs and loose dry activity during the storm. 

Snowpack Summary

Up to 20 cm of new snow has buried heavily wind affected snow surfaces in exposed terrain, a melt-freeze crust at low elevations and on solar aspects extending into the alpine, and surface hoar in sheltered terrain. The January 18 melt-freeze crust extends up to around 2000 m elevation and can be found down around 20 cm.  

The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches during the third week of January but is now considered dormant after a week of cold, dry weather. While this layer is not currently considered a front page avalanche problem, we continue to track it and expect it will wake up again with major warming or a large storm event. This recent forecaster blog goes into more details on the layer.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs 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.

Problems

Wind Slabs

An icon showing 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 has now shifted to the NW so wind slabs should be expected on most aspects.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 1st, 2022 4:00PM

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