Avalanche Forecast

Issued: Apr 19th, 2021 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Loose Wet and Cornices.

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The best and safest riding will be in north-facing terrain that is free from cornices overhead. Plan your day around avoiding sun-exposed slopes. 

Summary

Confidence

Moderate - Uncertainty is due to rapidly fluctuating freezing levels.

Weather Forecast

Warm sunny weather continues until a weak frontal system arrives on Thursday.

TUESDAY NIGHT: Clear skies, light northeast wind, freezing level drops to 1500 m with treeline temperatures dropping to -3 C.

MONDAY: Sunny, light wind, freezing level climbing to 2200 m with treeline temperatures reaching +1 C.

WEDNESDAY: Sunny with some clouds in the afternoon, light northwest wind, freezing level climbs to 2400 m with treeline temperatures reaching +3 C.

THURSDAY: Scattered flurries bring 5-15 cm of snow above 1800 m and light rain in the valleys, light northeast wind, freezing level around 1800 m with treeline temperatures around -1 C.

Avalanche Summary

Multiple days of above freezing temperatures resulted in widespread wet loose and wet slab avalanches on sun-exposed slopes between Thursday and Saturday. The wet loose avalanches were mostly size 1-2, but some of the wet slab avalanches were quite large and destructive (size 2.5-3.5). The large wet slabs were mostly on south and west facing slopes. See a photo of a recent wet slab in Glacier National Park here.

You can still expect wet loose avalanches and cornice falls on Tuesday, but they will be less widespread and destructive than they were over the weekend due to the relatively cooler temperatures.

Snowpack Summary

A surface crust will form overnight and then gradually break down with daytime warming. Dry snow may still be found in high north-facing terrain (above roughly 2300 m). There are no layers of concern in the snowpack, which has been melting and settling over the past week. Large cornices loom along many ridgelines.

Terrain and Travel

  • Avoid exposure to steep sun exposed slopes.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Loose Wet

An icon showing Loose Wet

Expect wet loose avalanches to run naturally when steep slopes are exposed to the sun. Activity will start on east-facing slopes in the morning, south-facing slopes throughout the day, and continue on west-facing slopes into the evening.

Aspects: East, South East, South, South West, West.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are large and fragile when exposed to the sun. Cornice falls are dangerous on their own and can possibly trigger avalanches on slopes below.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 20th, 2021 4:00PM