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Archived

Avalanche Forecast

Dec 22nd, 2018–Dec 23rd, 2018
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: Glacier.

Tread cautiously in the hills today. Cold temp's should tighten the snowpack, but sunshine on steep southerly aspects may cause a natural avalanche cycle.

Weather Forecast

A short-lived high-pressure ridge sits over us today. Cooler temp's (-11°c in alpine), light ridge-top winds, and plenty of sunshine on Saturday. Slightly warmer on Sunday and Monday (-7°c in alpine), with isolated flurries and light to moderate SW winds.

Snowpack Summary

50cm+ of storm snow has settled into a surface slab at all elevations. Cooler temp's may make it stubborn to trigger. The Dec 9 surface hoar/facet/crust persistent weak layer is buried 90cm+ and is producing large whumphs and sudden planar results. The Nov 21 surface hoar/facet persistent weak layer is down ~140cm.

Avalanche Summary

A widespread natural avalanche cycle to sz 3-3.5 occurred Thursday night with the strong/extreme SW winds. Artillery control during the day produced avalanches from sz 2 to 3.5 in the highway corridor. Avalanche debris from Dispatcher's Bowl and Grizzly Peak was observed at valley bottom and across Connaught Creek, large sz 3.5's from the storm.

Confidence

Avalanche Problems

Storm Slabs

50cm+ of storm snow, accompanied by strong SW winds and warm temp's, has formed a storm slab at all elevations; especially in immediate lee features below ridge crests and on cross-loaded slopes. Solar input may trigger slabs on steep, S'ly aspects.
If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Recent snow may be more sensitive to human triggering on solar aspects where it sits on sun crust

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

The Dec 9 weak layer is down 80-110cm and consists of surface hoar, facets, and sun crust, depending on the aspect. Sudden planar results are being seen on this layer. Natural and human triggered avalanches may still occur on this layer.
Watch for whumpfing, hollow sounds, and shooting cracks.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3.5