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Archived

Avalanche Forecast

Dec 17th, 2021–Dec 18th, 2021
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Glacier.

The incoming storm will reach it's peak Saturday afternoon, expect a natural avalanche cycle around that time.

Uncertainty surrounds the effect of this storm on the Dec. 1st persist weak layer, give large avalanche terrain a miss until this plays out.

Weather Forecast

A warm front will hit our area early Saturday morning, bringing snowfall, warming temps, and strong winds.

Tonight: Clear periods. Alpine low -19*C. Light S ridge winds

Saturday: Snow (22cm).  High -9*C. Strong SW winds

Sunday: Sunny periods, a few flurries. Low -15*C, High -9*C. Light N winds

Monday: Mostly sunny.  Low -22*C, High -13*C. Light SW wind

Snowpack Summary

Incoming new snow will fall on previously facetted low density snow. The Dec 1 crust is ~10cm thick, buried a ranging depth of 50-100cm, and can be found up to 2300m. Signs of facetting have been found above and below this crust, particularly in shallow snowpack areas at and just below treeline.

Avalanche Summary

A few small-large natural avalanches where observed in the highway corridor on Friday, these were failing as loose dry and thin soft slab avalanches. 

Snowpack tests continue to give sporadic sudden results on the Dec. 1st crust, particularly in shallower snowpack areas at Treeline.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

Incoming new snow will not likely bond well to previously facetted surfaces. Warmer temps and strong winds will cause rapid slab formation.

  • Minimize overhead exposure during periods of heavy loading from new snow, wind.
  • Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1.5 - 3

Persistent Slabs

The Dec 1st crust is buried by 40-100 cm of snow. Be especially cautious in thinner snowpack areas, where it is more likely to be reactive. The crust is most reactive at tree line, but it is present below tree line and in the lower alpine.

  • Avoid steep convexities or areas with a thin or variable snowpack.
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3

Loose Dry

Expect loose dry avalanches in steep terrain.

  • Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2