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Archived

Avalanche Forecast

Apr 30th, 2023–May 1st, 2023
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high

Regions: Glacier.

The snowpack is soft and mushy from valley bottom to mountain-top, creating very dangerous avalanche conditions that are best to be avoided.

Best to pick a different, more summer-related activity for the next few days (pickle ball, biking, bird-watching, etc).

Confidence

High

Avalanche Summary

Numerous loose snow and slab avalanches, to sz 3, were observed on Friday and Saturday. They appeared to be gouging further into the snowpack. Several deeper slab avalanches are suspected to have failed on the Mar. 31st crust.

Avalanches may to continue to increase in size as the snowpack warms.

Snowpack Summary

At upper elevations, warm temperatures and minimal overnight refreeze is weakening a moist upper snowpack. Several crusts buried in the top 50cm of the snowpack are beginning to break down as the snow warms. 20-40cm above the ground, the Nov 17 basal weakness can still be found in many areas.

Below treeline, the entire snowpack has become isothermal, and is losing strength as the day warms.

Weather Summary

Warm, sunny weather through the weekend, with above seasonal temps, high freezing levels (FZL), and no overnight freeze in the Alpine.

Tonight: Mostly clear, Alpine Low 11°C, FZL 3400m, Light SW ridgetop wind.

Mon: Isolated showers, High 15°C, FZL 3700m.

Tues: Mix of sun/cloud, Low 9°C, High 12°C, FZL 3800m.

Terrain and Travel Advice

  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid exposure to overhead avalanche terrain as temperatures increase.

Avalanche Problems

Loose Wet

With intense solar heating and very little overnight refreeze the surface snow is moist and weak. Loose wet avalanches are easily triggered in steep terrain and can gain surprising mass.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 3

Wet Slabs

Several buried crusts exist in the upper snowpack, the deepest of which is the Mar 31 layer. As the upper snowpack loses strength and cohesion during this intense warm up these crusts may provide a failure plane for the wet snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3

Deep Persistent Slabs

The increasing warmth is penetrating deep into the snowpack. The potential for this early season basal weakness to wake up and produce very destructive avalanches increases with each day of warming.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4.5