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Avalanche Forecast

Feb 23rd, 2020–Feb 24th, 2020
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
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

Regions: North Columbia.

The developing storm slabs are expected to be reactive to human triggers on Monday. Careful terrain selection and route finding will be required to effectively manage risk.

Confidence

High - The snowpack structure is generally well understood.

Weather Forecast

SUNDAY NIGHT: 5-10 cm snow, moderate southwest wind, alpine temperature -8 C, freezing level below valley bottom.

MONDAY: Mostly cloudy with possible flurries; 0-5 cm, light west wind, alpine temperature -5 C, freezing level 700 m

TUESDAY: Mostly cloudy, light to moderate west wind, alpine temperature -6 C, freezing level 700 m.

WEDNESDAY: Mix of sun and cloud, light to moderate west wind, alpine temperature -3 C, freezing level rising to 1200 m.

Avalanche Summary

On Saturday the new snow was reported as being reactive to skier traffic as a very thin soft slab, especially in wind affected terrain. These slabs will become increasingly touchy as the new snow stacks up and settles into a cohesive slab.

Snowpack Summary

15-25 cm of recent snow has buried a widespread layer of surface hoar (size 10-20 mm.). This layer exists at all elevations. This same layer of surface hoar has been reported as sitting on a thin sun crust on solar aspects which is a particularly nasty combination. The new snow will likely become increasingly reactive to human triggers as it stacks up and settles into a cohesive slab. The early February rain crust down 70-100 cm. is another prominent layer in the upper snowpack that requires monitoring, though there have been no recent avalanches on this layer. The mid and lower snowpack is generally well settled and strong.

Terrain and Travel

  • Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Be alert to conditions that change with elevation, aspect and exposure to wind.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Avalanche Problems

Storm Slabs

25-35 cm. of recent snow is sitting on top of a widespread layer of surface hoar at all elevations. On solar aspects the surface hoar is sitting on a crust, a particularly nasty combination.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2