Avalanche Forecast

Issued: Dec 25th, 2018 3:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs.

dsaly, Avalanche Canada

Lizard-Flathead.

Persistent slabs are tricky to manage and generally require patience and conservative terrain choices. Check out the new Forecaster Blog for a great explanation on how to best manage a persistent slab problem. Click here to read the blog.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Clear. Light southwest wind. Alpine low of -12C.WEDNESDAY: 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: Mix of sun and cloud. Light increasing to moderate west wind. Alpine high of -11C.

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 new 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.

Problems

Persistent Slabs

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

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Pay attention to overhead hazards like cornices which could trigger the persistent slab.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 26th, 2018 2:00PM