Avalanche Forecast

Issued: Mar 5th, 2021 4:00PM

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

Avalanche Canada astclair, Avalanche Canada

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As the storm eases and temperatures drop, the snowpack is beginning to gain strength. However, triggering storm slabs at upper elevations remains likely, especially in wind-drifted areas. Dial back terrain choices where you find more than 20 cm of snow.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

A parade of storms continues through the weekend

Friday night: Overcast, 5-10 cm of snow above 1000 m, moderate southwest wind, freezing level dropping to 700 m.

Saturday: Overcast, up to 5 cm of snow, light southwest winds, freezing level near 1000 m. 

Sunday: Overcast, 20-30 cm of snow, moderate to strong south winds, freezing level near 800 m. 

Monday: Clearing skies, isolated morning flurries with up to 5 cm of snow, light southeast winds, freezing level rising to 1200 m by end of day.

Avalanche Summary

Storm slabs are expected to be reactive at upper elevations, where recent snow and strong winds have created conditions that are primed for human triggering. 

Cornices may reach their breaking point. See this MIN for an example from Sky Pilot last Sunday.

Snowpack Summary

20-30 cm of recent storm snow blanketed slopes above 1300 m on Friday. This snow was accompanied by strong south winds, forming touchier slabs on leeward slopes. Massive cornices exist on ridgelines, which can act as triggers on slopes below. Freezing levels remained elevated throughout the storm, saturating the snowpack below 1300 m. A cooling trend over the weekend is expected to settle and strengthen the snowpack below this widespread March 5th rain crust. 

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Choose conservative terrain and watch for clues of instability.
  • Cornice failure may trigger large avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs

Recent snow has formed a widespread storm slab problem at upper elevations. Storm slabs will likely be more reactive in wind-drifted areas. The combination of wind and snow has the potential to weaken cornices, which can act as triggers on slopes below.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1.5 - 2.5

Valid until: Mar 6th, 2021 4:00PM