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Archived

Avalanche Forecast

Dec 17th, 2020–Dec 18th, 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
4: High
The avalanche danger rating in the alpine will be high
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
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
4: High
The avalanche danger rating below treeline will be high

Regions: Glacier.

All winter permit areas are closed today. We are in a period of prolonged storm with increasing avalanche danger.

Weather Forecast

Flurries today with accumulations around 6cm.

Alpine temperature: High -6 °C.

Ridge wind west: 30-45 km/h.

Freezing level: 1300 metres.

Friday periods of snow accompanied by strong SW winds, with accumulations around 20cm.

Saturday the storm cycle continues with another 10cm cooling temps and strong SW winds.

Snowpack Summary

10cm+/- of new snow brings our storm total to ~50cm in the last 72hours. Mod S-SW winds and mild temperatures are forming soft storm slabs at all elevations. Weak layers; Dec 13 Surface Hoar and Dec 7 crust/Surface Hoar are in the top 60cm.  Deeper in the snowpack the Nov 5th  crust is currently unreactive to stability tests or skiers.

Avalanche Summary

A skier went  for a ride in a size 1.5 slab avalanche  below treeline yesterday. They were uninjured.  Numerous avalanches to size 3 along the highway corridor yesterday morning. Of note were slab releases initiating at below treeline elevations. Winds are picking up this morning with  corresponding new avalanche activity.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

Storm snow totals are eclipsing 50cm in the last 72 hours at Treeline. Mod S-SW winds and mild temperatures have formed storm slabs at all elevations. Storm slabs are failing on the Dec 13th Surface Hoar Layer.

  • Watch for whumpfing, hollow sounds, and shooting cracks.
  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2.5

Loose Dry

Sluffing continues to be a concern with significant amounts of new snow over the last 48 hours. Loose dry avalanches will have enough mass to push riders around in steep terrain. Extra care is required around cliffs and confined gullies.

  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

70cm sits on the Dec 7th weak interface of rain crust/sun crust/surface hoar combo. Our new storm slab could easily step down to this interface, significantly increasing the size and destructive potential.

  • 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: 1 - 3