Avalanche Forecast

Issued: Mar 29th, 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 and Cornices.

Avalanche Canada swerner, Avalanche Canada

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Storm slabs at higher elevations may be reactive on Tuesday, especially in wind-loaded areas.

If the sun pokes through the clouds it can quickly initiate natural avalanches and weaken cornices. 

Summary

Confidence

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

Weather Forecast

A ridge of high pressure will dominate for the next couple of days bringing cooler and dryer conditions.

Tuesday: Mainly cloudy. Ridgetop wind moderate from the northwest. Alpine temperatures near -2 and freezing levels 1000 m.

Wednesday/ Thursday: Mix of sun and cloud with some snow expected Thursday up to 5 cm. Ridgetop wind moderate from the southwest. Alpine temperatures near +1 and freezing levels 2000 m. 

Avalanche Summary

On Sunday, natural storm slab avalanches up to size 2 were reported and numerous size 1.5 slabs were easily triggered by skiers and riders from steep slopes where the new snow sits above a crust. 

The likelihood of triggering avalanches will decrease somewhat in the wake of Sunday's storm, however, human triggering remains likely, especially in wind loaded areas at upper elevations. With so much new snow, even short periods of direct sun can trigger natural avalanches. Cornices are large and should be given a wide berth, especially when the sun comes out.

Snowpack Summary

20-40 cm of new snow fell throughout the region since Saturday night. This sits above a widespread melt-freeze crust, with the exception of high north-facing terrain. It may also be sitting on small surface hoar crystals reported on north and east aspects in the alpine. This recent precipitation likely fell as rain in many areas below treeline. The snow surface has likely frozen into a crust at lower elevations.

Cornices along ridgelines are large, and the likelihood of them failing will increase when the sun comes out.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Brief periods of sun could quickly initiate natural avalanche activity.
  • Be aware of highly variable recent wind loading patterns.
  • Cornices become weak with daytime heating or solar exposure.

Problems

Storm Slabs

An icon showing Storm Slabs

Recent fresh snow and strong winds have formed widespread storm slabs that are likely still easy to trigger, especially in wind loaded areas.

With all of this new snow, even brief periods of sun can quickly trigger natural avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind. Direct sun can weaken cornices significantly.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

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

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