Avalanche Forecast

Issued: Dec 23rd, 2021 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Loose Dry and Persistent Slabs.

Chris Gooliaff,

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Soft slabs and fast, loose avalanches will be easy to trigger under the weight of a person for the next couple of days. Be aware this additional load could be enough to trigger a deeper slab on the Dec 1 crust.

Summary

Weather Forecast

Cold air from the north smacks into moist, warmer air from the SW for the next couple of days, bringing light/mod snowfall to the region.

Tonight: Flurries, Alp low -14*C, light SW winds

Fri: Flurries, 5cm, Alp high -11*C, light SW winds

Sat: Flurries, 10cm, Alp high -11*C, light/gusting strong S winds

Sun: Flurries, trace, Alp high -22*C, light E wind

Snowpack Summary

40+cm of snow and moderate S'ly winds have formed a storm slab on top of cold, faceted surfaces. The December 1st crust is buried approximately 80cm-150cm, with weaker sugary snow directly above and below. Beneath the Dec 1st crust-facet combo, the snowpack is dense and strong.

Avalanche Summary

Strong gusty winds, new snow, and warming temperatures triggered a natural avalanche cycle Thurs morning to sz 3.5. Artillery control has produced numerous sz 3-3.5 avalanches to valley bottom. Human triggered avalanches are likely in steep, unsupported terrain.

Confidence

Forecast snowfall amounts are uncertain

Problems

Storm Slabs

An icon showing Storm Slabs

40+cm of new snow fell Wed/Thurs. All this new snow combined with moderate winds and a slight rise in temperature has formed soft slabs in many locations, and most problematic in the Alpine and at TL.

  • Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Loose Dry

An icon showing Loose Dry

40+cm of new snow on cold, sugary facets will ensure loose, dry avalanches in steep, unsupported terrain. Be aware of terrain traps (gullies, tree wells, etc), where even a small avalanche could have dire consequences.

  • Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.
  • Be careful of loose dry power sluffing in steep, confined or exposed terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

The Dec 1st crust is buried by ~130 cm of snow and is of most concern at treeline elevation. Small facets (sugary snow) has been forming above and below the crust. It has been unreactive recently, but with increasing load it could wake up.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Dec 24th, 2021 4:00PM