Archived

Avalanche Forecast

Dec 26th, 2018–Dec 27th, 2018

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

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: Lizard-Flathead.

Persistent slabs are tricky to manage. Avalanche activity is receding, but if triggered, an avalanche falling on the persistent weak layer could have serious consequences. Read the latest Forecaster Blog on the persistent slab problem here.

Confidence

Moderate -

Weather Forecast

WEDNESDAY NIGHT: Cloudy with isolated flurries, trace accumulation. Light southwest wind. Alpine high of -9C.THURSDAY: Mix of sun and cloud. Light northwest wind. Alpine high of -9C.FRIDAY: Mainly cloudy with isolated flurries, trace accumulation. Light to moderate west-southwest wind. Alpine high of -11C.SATURDAY: Cloudy with scattered flurries, accumulation up to 5 cm. Moderate southwest wind. Freezing level rising to 1500 m.

Avalanche Summary

Over the weekend, explosives triggered avalanches to size 2.5 and natural avalanches to size 2 were reported. On Sunday, wind redistributing new snow resulted in numerous natural wind slabs avalanches (size 1) noted in the region.

Snowpack Summary

Up to 20 cm of fresh snow is being redistributed into soft wind slabs in lee areas at treeline and alpine elevations. A combined total of 60-110 cm of recent snow has formed a slab that sits on a persistent weak layer that formed in early December. This layer mostly consists of facets (sugary snow) with some isolated areas also containing small surface hoar (feathery crystals). Several other weak layers have been observed in the lower snowpack such as crusts and facets that formed in late October/early November. The potential may exist for avalanches triggered on the persistent slab to step down to these lower layers, resulting in large, destructive avalanches.

Avalanche Problems

Persistent Slabs

60-110 cm of snow sits on a weak layer consisting primarily of facets (sugary snow). Winds have redistributed recent snow and slabs may be more reactive in wind-loaded terrain.

Watch for whumpfing, hollow sounds, and shooting cracks.Be cautious as you transition into wind affected terrain.Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3