Avalanche Forecast

Issued: Apr 22nd, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Cool cloudy weather will make avalanche conditions safer. Be careful around cornices and the isolated areas where the snowpack isn't capped by a thick crust. 

Summary

Confidence

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

Weather Forecast

Thursday night: Partly cloudy with isolated flurries, light wind, alpine temperature near -7, freezing level valley bottom.

Friday: Partly cloudy, light wind, alpine high near -3, freezing level 2000 m.

Saturday: Flurries bringing up to 5 cm, light wind, alpine high near -4, freezing level 1700 m.

Sunday: 10-20 cm new snow, moderate to strong southwest wind, alpine high near -4, freezing level 1700 m.

Avalanche Summary

Warm temperatures last week resulted in widespread wet avalanche activity. The most notable activity was on Saturday where there was both widespread size 1-2 wet loose avalanches and a few larger and destructive (size 2.5-3.5) wet slab avalanches. The large wet slabs were mostly on south and west facing slopes. Avalanche activity has been on the decline since then with relatively cooler temperatures. A cornice fall triggered a large (size 3) slab avalanche on a north-facing alpine ridge in Glacier National Park on Tuesday.

The cooling trend will make wet avalanches problems less likely in the coming days, but brief periods of sun could still promote wet loose avalanches in isolated areas. The primary concern will be cornice falls.

Snowpack Summary

A dusting of recent snow may sit above a thick surface crust. The upper snowpack has undergone multiple melt-freeze cycles and is now crusty and refrozen in the cooler temperatures. Dry snow may still be found on northerly aspects above roughly 2400 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

  • 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.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

Cornices

An icon showing Cornices

Minimize your exposure below cornices. 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

Unlikely - Possible

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet

Small loose wet avalanches are possible in new snow at upper elevations and wet snow at lower elevations that hasn't refrozen overnight.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 23rd, 2021 4:00PM