Avalanche Forecast

Issued: Dec 5th, 2017 4:59PM

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

shorton, Avalanche Canada

Purcells.

One more day of cool weather before alpine temperatures soar. Watch for wind slabs on Wednesday and avoid slopes getting hit by the sun.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

WEDNESDAY: Sunny with valley cloud in the morning, light northwest wind, inversion forming with alpine temperatures reaching -4 C.THURSDAY: Sunny with valley cloud, light wind, inversion with freezing level up to 3000 m.FRIDAY: Sunny with valley cloud, light wind, inversion with freezing level up to 2700 m.

Avalanche Summary

Limited reports from the region over the past few days show a pattern of touchy wind slabs around alpine ridges. On Tuesday, a size 1.5 wind slab was triggered by a skier on a south-facing slope at 2600 m in the Invermere area. A Mountain Information Network (MIN) report describes multiple size 1 wind slabs triggered by ski cutting from the Golden area on Sunday. Several size 1 wind slabs were also triggered by explosives near ridge crests throughout the region over the weekend.

Snowpack Summary

Snow from last week's storms is settling and getting redistributed into fresh wind slabs by northwest winds. Roughly 20-40 cm of recent snow sits above various crusts from the warm weather in late November. Two deeper layers may be found in the snowpack, including the November 10 surface hoar and the Halloween crust (80 to 100 cm deep). The late November crust is the most likely of these layers to develop into a problem in the future. Snow depths decrease rapidly below treeline, where the primary hazards are rocks, stumps, and open creeks.

Problems

Wind Slabs

Fresh wind slabs have been forming throughout the week, so be careful around ridges and gullies. Solar warming may make slabs extra reactive on south-facing slopes.

Travel on ridgetops to avoid wind slabs on slopes below.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 6th, 2017 2:00PM