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Avalanche Forecast

Feb 28th, 2024–Feb 29th, 2024
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
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

More snow and wind arriving Wednesday night means avalanche danger will remain High. Persistent slab avalanches are primed for rider triggering.

Confidence

Moderate

Avalanche Summary

Numerous natural and rider triggered storm slab and persistent slab avalanches size 1 to 3 have been reported the past few days in the alpine and treeline elevation bands on all aspects. Most of these occurred on the weak layer of faceted grains 60-100 cm deep sitting on a crust formed in early February. Several were reported as remotely triggered (from a distance).

Expect rider triggered avalanches to be likely as more snow and wind arrives Thursday night.

Snowpack Summary

70 to 110 cm of recent snow sits on a variety of layers that it may not bond well to, including surface hoar in wind-sheltered terrain, weak facets, or a hard melt-freeze crust on sun-exposed south and west-facing slopes. The wind has likely formed thicker deposits in lee terrain features near ridges.

A thick and hard widespread crust that formed in early February is buried 50 to 100 cm deep and is found up to around 2400 m. This crust may have a layer of facets above it, which makes it a troublesome avalanche layer.

The remainder of the snowpack is settled.

Weather Summary

Wednesday Night

Cloudy with 10 to 20 cm of snow. 30 to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1000 m.

Thursday

Cloudy with 5 to 15 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -7 °C. Freezing level at valley bottom.

Friday

Mostly cloudy with sunny breaks and 1 to 3 cm of snow. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -7 °C.

Saturday

A mix of sun and cloud, 15 to 25 km/h southeast, Treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.
  • Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Avalanche Problems

Storm Slabs

Storm slabs are likely to remain reactive to human traffic, particularly where they sit on problematic weak layers or hard surfaces. Giving the snow time to heal is warranted at this time.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1.5 - 2.5

Persistent Slabs

A weak layer of faceted grains above a melt-freeze crust buried 50 to 100 cm deep is a recipe for large, high-consequence avalanches. This snowpack setup will take some time to strengthen.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 3.5