Avalanche Forecast

Issued: Feb 24th, 2018 4:34PM

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

Avalanche Canada mconlan, Avalanche Canada

Storm slabs have formed with recent snowfall. The snow fell with strong southerly winds, so expect thicker slabs in lee features. Watch for avalanche activity and signs of locally unstable snow, such as whumpfing and shooting cracks.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

SUNDAY: Cloudy with early-morning snowfall, accumulation 5 to 10 cm, moderate to strong westerly winds, alpine temperature -10 C, freezing level 800 m.MONDAY: Mostly sunny, light northwesterly winds, alpine temperature -10 C, freezing level 800 m.TUESDAY: Cloudy with light snowfall, accumulation 5 cm, light to moderate southwesterly winds, alpine temperature -10 C, freezing level 800 m.

Avalanche Summary

On Friday and Saturday, storm slabs were triggered by skiers and explosives around treeline and alpine elevations, 10 to 25 cm deep. Otherwise, natural and skier-triggered sluffing was experience in steep terrain.Expect new snowfall to not bond well to underlying snow surfaces and hence be reactive to skier traffic.

Snowpack Summary

Around 5 to 10 cm of storm snow on Friday night and another 5 to 10 cm is expected Sunday. The snow fell with strong southerly winds, producing slabs on all aspects with deeper deposits in lee features. This snow fell on variable surfaces, including wind-affected, weak surface hoar, and weak faceted snow. The new snow will likely not bond well to these surfaces and is expected to be reactive to both natural and human triggers. Beneath the new snow, variable surface hoar, faceted snow, and crusts exists around 30 to 50 cm deep, which have been reactive to human traffic.Deeper in the snowpack, weak layers that formed in January and December are gradually gaining strength. The layers include several surface hoar and facet layers buried 1-2 m below the surface and a crust/ facet interface near the base of the snowpack. No avalanches have been reported on these layers for the past two weeks and snowpack tests are showing improved bonding. Despite these signs, avalanche professionals are still treating these layers with respect and being cautious around shallow start zones and in big avalanche paths.

Problems

Storm Slabs

An icon showing Storm Slabs
New storm slabs have formed, which may not bond well to underlying surfaces. Stiff slabs from last week still exist, which are about 30-50 cm deep and sit on variable weak surfaces. Old and new slabs have been reactive to human triggers.
If triggered, wind slabs may step down to deeper layers, resulting in large avalanches.Approach lee and cross-loaded slopes with caution.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Feb 25th, 2018 2:00PM

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