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Archived

Avalanche Forecast

Dec 18th, 2020–Dec 19th, 2020
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
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.

The AVALANCHE danger is increasing with the building storm slab over  weak surface hoar. Make conservative terrain choices.

Weather Forecast

Flurries today with another 7cm of accumulation.

Alpine high of -6C with ridge winds SW moderate to strong.

Freezing level 1200m.

Tonight through Sunday upwards of 30cm storm snow accompanied by SW winds moderate gusting to extreme.

Snowpack Summary

Wind, warmth and continued snowfall have formed a sensitive storm slab at all elevations over the Dec 13 surface hoar layer. Weak layers of concern are Dec 13 surface hoar down 45cm+ and Dec 7 crust/surface hoar layer down 65cm+. The Nov 5 crust has been unreactive to stability tests.

Avalanche Summary

Numerous size 1-2 skier remote avalanches were triggered yesterday both in the west end of the park and the Asukan and Illecillewaet valleys. On Wednesday a skier went for a ride in a size 1.5 slide below treeline elevation. Numerous avalanches to size 3.5 were recorded in the highway corridor yesterday.

Confidence

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

Avalanche Problems

Storm Slabs

Storm slabs continue to build over the Dec 13 surface hoar layer. This layer, down 40cm+, was very sensitive to human and natural triggering yesterday. This layer is reactive at all three elevation bands.

  • 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: Very Likely

Expected Size: 1 - 3

Persistent Slabs

70cm+ sits on the Dec 7th weak interface of rain crust/ surface hoar. If triggered the storm slab has potential to step down to this interface triggering large avalanches.

  • Minimize overhead exposure during periods of heavy loading from new snow, wind.
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3