Avalanche Forecast

Issued: Dec 10th, 2017 3:49PM

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

jlammers, Avalanche Canada

Lizard-Flathead.

Warm temperatures and solar radiation may elevate the avalanche danger at higher elevations on Monday.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Expect mainly clear skies and valley cloud for the forecast period. An inversion is forecast for all 3 days with high alpine temperatures peaking at 5 degrees on Monday and Tuesday. Winds are expected to remain light to moderate from the west.

Avalanche Summary

On Friday a few stiff wind slabs to size 1.5 were explosive-triggered at treeline. No other avalanches have been reported since. Looking forward, we should see a gradually diminishing potential for wind slab releases as warm daytime temperatures and overnight cooling promote bonding in the upper snowpack. The band of warm air associated with the inversion has been hovering at elevations higher than most peaks in the area. If this band of warm air drops, we may likely see a round of loose wet avalanche activity in steep, sun-exposed terrain.Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Stiff wind slabs exist on a wide range of aspects on alpine and exposed treeline slopes. In sheltered treeline and below treeline terrain, I suspect light amounts of low-density snow intermingle with surface hoar and surface facets.Roughly 30-60 cm below the surface you'll likely find a hard crust that was buried on November 26. This crust is approximately 30 cm thick and extends from 1600 m to mountain top on all aspects. Below this crust, the snowpack is moist to ground. Average snowpack depths at treeline elevations in the region range from 80-120 cm.

Problems

Wind Slabs

Variable winds from last week have formed wind slabs on a wide range of aspects at higher elevations. Be especially cautious of reverse loaded or cross-loaded slopes that see sun exposure.

Be careful with wind loaded areas, especially near ridge crests and roll-overs.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

The band of warm air associated with the inversion has been hovering at elevations higher than most peaks in the area. If this band of warm air drops, we may see a round of loose wet avalanche activity in steep, sun-exposed terrain.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 11th, 2017 2:00PM