Archived

Avalanche Forecast

Dec 20th, 2016–Dec 21st, 2016

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Deep storm snow with strong winds and a weak old snow surface has elevated avalanche hazard! Limit your exposure to avalanche terrain.

Weather Forecast

The next pulse of the storm will bring an additional 10 cm of snow today. The alpine high should reach -8 deg with winds from the Southwest 25 gusting to 80 kph. Wednesday should bring a break from the snowfall then another 10cm is expected Thursday.

Snowpack Summary

50cm+ of storm snow in the last 48hrs and winds to 85kph have built storm slab and windslabs at all elevations. This new significant snow load sits on a facetted, weak snowpack. We're calling this new snow interface the Dec 18th layer which is a mix of surface hoar and facets. As the new snow settles into a slab the Dec 18th will become reactive

Avalanche Summary

Yesterday we observed a widespread natural avalanche cycle to size 3.0. These were both slabs and loose avalanches reaching well into the runouts. Whumphing and shooting cracks from ski tips were also observed by groups that were out skiing. With continued snowfall the slab will remain touchy &natural avalanche activity will continue today.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

50cm of storm snow with strong gusting winds is sitting over a very weak old surface of facetted snow. Cracking and whumphing was observed yesterday from groups out skiing. With additional snowload and settlement the surface slab will remain touchy

Use conservative route selection, choose moderate angled and supported terrain with low consequence.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 4

Loose Dry

Where the new snow is unconsolidated heavy sloughing is expected. Add another 10cm of new snow today and in steep terrain these slides could entrain enough mass to be an issue for skiers and riders.

Be aware of party members below you that may be exposed to your sluffs.Use caution above cliffs where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2