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Archived

Avalanche Forecast

Apr 24th, 2023–Apr 25th, 2023
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions:

Numerous very large deep persistent slab avalanches have been reported on a variety of aspects in the alpine.

Recent snow and southerly wind may have formed fresh wind slabs on lee features.

Confidence

Low

Avalanche Summary

No avalanches were reported on Sunday. However, observations in this region are currently very limited.

Numerous naturally triggered very large (up to size 3.5) deep persistent slab avalanches were reported on a variety of aspects in the alpine on Friday. They failed on either a crust/facet layer 100+cm deep or weak facets at the bottom of the snowpack. Follow the link on this MIN for the photos of these notable avalanches.

Observations are limited at this time of year, please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.

Snowpack Summary

Recent snow and southerly wind may have formed fresh wind slabs on lee features.

A weak layer of crust/facets down 100+ cm and/or weak facets at the bottom of the snowpack have recently become reactive.

Cornices are large and loom over slopes below like gargoyles.

Weather Summary

Monday Night

Mostly cloudy with flurries; 5-10 cm / 20 km/h south ridgetop wind / Temperature at treeline around -5 C / Freezing level valley bottom

Tuesday

Mix of sun and cloud / 30 km/h south ridgetop wind / Temperature at treeline around -3 C / Freezing level 700 m

Wednesday

Mix of sun and cloud with isolated flurries; 3-5 cm / 20 km/h southeast ridgetop wind / Temperature at treeline around -1 C / Freezing level 1000 m

Thursday

Cloudy with flurries; 5-10 cm / 50 km/h south ridgetop wind / Temperature at treeline around -1 C / Freezing level 1000 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Cornice failure may trigger large avalanches.

Avalanche Problems

Deep Persistent Slabs

A weak layer of crust/facets down 100+ cm and/or weak facets at the bottom of the snowpack have recently become reactive.

Snowpack and avalanche observation data are currently very limited in this region which makes this kind of avalanche problem very difficult to forecast.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3.5

Wind Slabs

Recent snow and southerly wind may have formed fresh wind slabs on lee features.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Cornices are very large and loom over slopes below like gargoyles. Cornice falls may trigger large avalanches on the slopes below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1.5 - 2.5