Avalanche Forecast

Issued: Dec 21st, 2017 3:40PM

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

jfloyer, Avalanche Canada

Lizard-Flathead.

The character of a buried weak layer about 50 cm below the surface is not well known. It could give surprises. A cautious approach to travel is recommended.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Thursday night: 5-10 cm new snow expected.Friday: Flurries. Light northeasterly winds. Treeline temperatures around -12C.Saturday: Dry and sunny. Moderate northwesterly winds. Temperatures around -15C.Sunday: Dry and sunny. Light northwesterly winds. Temperatures around -15C.

Avalanche Summary

A natural avalanche cycle up to size 2.5 was observed on Wednesday with avalanche depths typically 50 cm deep. On Thursday, ski cutting readily released avalanches in wind-loaded terrain on mainly southeast to north aspects.

Snowpack Summary

Around 50cm recent new snow now rests on a variety of old surfaces. These old surfaces include crusts on south through west facing slopes, wind-scoured slopes and, in sheltered terrain at and below treeline, large feathery surface hoar crystals. Lower in the snowpack, you should be able to find a hard crust that was buried near the end of November. This crust is approximately 30cm thick and extends from 1600m to mountain top on all aspects. Average snowpack depths at treeline in the region range from 100 to 140cm.

Problems

Wind Slabs

Wind slabs exist in exposed terrain due to recent new snow and wind.

Avoid freshly wind loaded features.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A variable weak layer buried approximately 50 cm below the surface will likely remain sensitive to human-triggered avalanches after the storm ends. Sheltered areas with steep, unsupported terrain are the most likely places to be caught.

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: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 22nd, 2017 2:00PM