Avalanche Forecast

Issued: Dec 29th, 2018 4:42PM

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

jfloyer, Avalanche Canada

Lizard-Flathead.

I'm expecting some overnight snow that is likely to get blown into fresh wind slabs in exposed areas.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SATURDAY NIGHT: 15-20 cm additional new snow expected. Strong southwesterly winds.SUNDAY: Mostly light snow with the occasionaly heavier flurry. 2-5 cm. Light or moderate northwesterly winds. Treeline temperatures around -4C.MONDAY: Dry with sunny breaks. Light northerly winds. Treeline temperatures around -12C.TUESDAY: Dry with sunny breaks. Light southwesterly winds. Treeline temperatures around -12C.

Avalanche Summary

Small (size 1.5) storm slabs were reported in response to skier traffic on Saturday.A great MIN report from Corbin on Thursday identifies a few slabs initiating in thin, rocky areas on a south aspect. Check out the report here.

Snowpack Summary

Saturday's storm added approximately 20 cm new snow, accompanied by strong southeasterly winds. In total, 80-130 cm of snowfall through December 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). All this overlies several other weak layers observed in the lower snowpack such as crusts and facets that formed in late October/early November. With this weak basal snowpack, it is possible that an avalanche triggered on the persistent slab would step down to these lower layers, resulting in a full depth avalanche.

Problems

Wind Slabs

Touchy wind slabs have formed where wind has blown recent new snow into denser pillows.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

70-120 cm of snow sits on a weak layer consisting primarily of facets (sugary snow). This layer could still be triggered, particularly on steep, convex slopes.

Avoid convexities or areas with a thin or variable snowpack.Be wary of slopes that did not previously avalanche.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 30th, 2018 2:00PM