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Avalanche Forecast

Dec 17th, 2017–Dec 18th, 2017
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
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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Columbia.

Snow amounts will gradually accumulate over a variety of potential weak layers in the coming days.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

MONDAY: Snow Sunday night into Monday accumulations 10-20cm then cloudy with scattered flurries / Light to moderate northwest / Alpine temperature -9 TUESDAY: Periods of snow accumulations 15-20cm / Light to moderate southeast wind / Alpine temperature -12 WEDNESDAY: Cloudy with isolated flurries, accumulation 5cm / Light north wind / Alpine temperature -15

Avalanche Summary

Recent reports of avalanche activity are limited to a few very soft slab and/or loose snow avalanches to size 1.5 on northerly aspects in the alpine. As snow amounts begin to accumulate in the coming days expect to see an increase in avalanche activity.

Snowpack Summary

The 15-25cm of new snow accumulating Friday through Sunday evening now sits on a wide variety of old surfaces including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. As the snow load builds and slab properties develop, it will be important to monitor how the new snow is bonding to the old surfaces. Most concerning would be areas that have surface hoar sitting on top of a hard crust. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 60-80cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it. Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.

Avalanche Problems

Storm Slabs

As the recent new snow accumulates over the next few days expect it to become reactive to human triggering
Watch for whumpfing, shooting cracks, or signs of recent natural avalanches.Be cautious as you transition into wind affected terrain.Buried surface hoar may be preserved on open slopes and convex rolls at and below tree line

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2