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Avalanche Forecast

Dec 8th, 2021–Dec 9th, 2021
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
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
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
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: Yukon.

It's a good time to go out, assessing slopes as you travel. If you get into wind affected terrain watch for windslabs, shooting cracks and drumming sounds. Thin snowpack areas are where you're most likely to tickle the basal weakness so don't have snowy slopes above you. 

Confidence

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

Weather Forecast

A quiet Thursday followed by stormy Friday

WEDNESDAY NIGHT: Light winds and precipitation ending. Temperatures have fallen to -10C and should continue dropping to around -15C overnight.

THURSDAY: Broken cloud cover, daytime high temp around -12 C, light wind generally out of the southwest, no snow expected.South winds expected to crank up Thursday night.

FRIDAY: The day will arrive with a bang: strong to extreme winds and around 10 cm of snow. A bit more during the day. as the storm and wind wind down. High temp around -10 C.

SATURDAY: Broken or overcast sky, light north east wind, a few flurries, and cooling temperatures nudging towards -20's C.

Avalanche Summary

Our AvCan field team reports whumpfs and shooting cracks up to 10 m from thin snowpack areas in the Fraser Chutes today (Wednesday).

Snowpack Summary

A drawing of my mental map of the snowpack is available here.

Terrain and Travel

  • Start with conservative lines and watch for clues of instability.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Avalanche Problems

Storm Slabs

The region picked up 15 to 20 cm of new snow Tuesday & Wednesday without much wind. There was likely enough southerly wind for isolated wind slabs north facing terrain where it has likely been formed into slabs. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 2.5

Deep Persistent Slabs

Whumpfing from thin snowpack areas in Fraser Chutes confirms this thing is real. The risk I picture is whumpfing from a thin rocky area and triggering a slope above you where it's down 100cm or more.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3