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Avalanche Canada rbuhler, Avalanche Canada

Lizard Range and Flathead Avalanche Forecast

Dec 18th, 2016 3:29PM

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

New snow and strong winds on Monday will form new wind slabs in exposed terrain. Use extra caution in wind affected terrain and avoid freshly wind loaded features.

Summary

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Weather Forecast

Around 15 cm of snowfall is expected for Monday with strong alpine wind from the west and treeline temperatures around -10C. A break is expected Monday night before another pulse of precipitation arrives on Tuesday. Models are currently showing another 5-15 cm with strong alpine wind from the southwest and treeline temperatures around -5C. Dry and sunny conditions are currently forecast for Wednesday.

Avalanche Summary

No new avalanches were observed on Saturday. On Friday, a few natural size 1 loose dry avalanches were observed out of steep terrain. On Thursday, a natural size 2 wind slab occurred in the Corbin area. This occurred at 2000m elevation on a northeast aspect as a result of recently strong southwest winds. Check out the MIN post for more details and a photo. On Monday, new snowfall and strong westerly winds are expected to result in new wind slab formation or add additional load to existing wind slabs which may still be lingering. Recent winds have mainly been from the southwest through northwest directions and wind slabs should be expected on opposite aspects in wind exposed terrain. The new snow buries a weak interface which may increase the reactivity of new slabs.

Snowpack Summary

The new snow buries a variable surface that developed over the last week of cold, dry, and windy conditions. This interface consists of scoured surfaces and wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar up to 20 mm in sheltered areas. In sheltered areas, there may be a layer of surface hoar in the upper snowpack which was buried around December 10. The mid pack is generally well settled. The thick crust from mid-November is near the bottom of the snowpack and reports suggest that the crust is currently well bonded to the surrounding snow.

Problems

Wind Slabs

An icon showing Wind Slabs
New snowfall and strong winds are expected to form new wind slabs in exposed terrain on Monday. Older wind slabs may also still be lingering. The new snow buries a weak interface which may increase the reactivity of new slabs.
Avoid slopes where the snow feels stiff or slabby.Use ridges or ribs to avoid pockets of wind loaded snow.Avoid freshly wind loaded features.

Aspects:

North, North East, East, South East, South.

Elevations:

Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 19th, 2016 2:00PM