Avalanche Forecast

Issued: Jan 29th, 2021 4:00PM

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

Avalanche Canada cmortenson, Avalanche Canada

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Assess conditions as you travel - Saturday may be a day of change as moderate to strong south wind impacts the region. Up to 15 cm of low density snow is available for wind transport and any resultant wind slabs may sit on top of a slippery surface hoar layer.  

Summary

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Light snow, increasing winds and warmer temperatures will be felt though the heavy storm passes to the south.

Friday night: Cloudy with clear periods and isolated flurries, trace of new snow, light to moderate southwest wind and alpine low temperatures -11C.

Saturday: Mainly cloudy with isolated flurries, trace to 5 cm new snow, moderate to strong south winds, increasing over the day and staying elevated overnight. Alpine high temperatures around -9.

Sunday: Cloudy with snow flurries, 5-15 cm new snow, strong south or southeast winds, alpine high temperatures around -6C.

Monday: Cloudy with isolate flurries and clear periods, trace to 10 cm new snow, mostly light south wind gusting strong and alpine high temperatures around -5C.

Avalanche Summary

There have been no recent avalanche reports in the region. As winds increase overnight on Friday and stay elevated as moderate to strong southerly wind on Saturday we anticipate wind slabs to form in open alpine, exposed ridge crests and open areas below treeline. 

We're continuing to track a layer of surface hoar from early January which has been trending towards unreactive. The most recent activity reported on this layer comes from January 16, when professional operators reported a small (size 1) avalanche releasing 40 cm deep. 

Recent observations from the north Blue River Valley describe this layer reacting to skier traffic on steep, unsupported features below treeline. This and snowpack tests that continue to sporadically produce easier, more sudden snowpack results make this layer worthy of continued monitoring.

Snowpack Summary

Up to about 15 cm of new low density snow has buried a weak layer of surface hoar. This surface hoar was reported to be widespread and grew on variable surfaces that include scoured and pressed surfaces in exposed terrain as well as faceted snow in more sheltered terrain. A thin sun crust may be found on steep solar aspects. Below 1600 m, 30-40 cm of snow is settling above a decomposing melt freeze crust. Check out this MIN from Chappell creek. 

A weak of layer of surface hoar from early January can now be found buried 40-70 cm deep. This layer last demonstrated reactivity over a week ago (Jan 16) in the south of the region near Valemount. It is most suspect in sheltered, open slopes at and below treeline. Although results from recent snowpack tests show increasingly resistant results (check out this MIN from near Barkerville), slope-specific assessment is warranted. 

Deeper in the snowpack, a couple of older persistent weak layers may still be identifiable from late and early December, consisting of surface hoar and a crust with faceted snow and buried anywhere from 70-150 cm deep. Prolonged periods of inactivity and unreactive snowpack test results suggest that these layers have trended towards dormancy. 

Terrain and Travel

  • Wind slabs are most reactive during their formation.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

Wind Slabs

An icon showing Wind Slabs

As wind increases to moderate overnight Friday recent low density snow will be available for transport. Activity may increase throughout the day on Saturday as wind increases to strong from the south. Reactive wind slabs will likely form in open alpine terrain, leeward pockets at ridgecrests, around exposed terrain features and in open areas below treeline.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 30th, 2021 4:00PM