Archived

Avalanche Forecast

Dec 16th, 2012–Dec 17th, 2012

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

Confidence

Fair - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

Overnight and Monday: A Low pressure system is moving into the region from the coast on Sunday evening. This system is expected to bring 15-20 mm of precipitation by late Monday morning. With the cool alpine temperatures, this may be 20-30 cms of light snow at higher elevations. Strong SW winds during the storm are expected to become strong NW after it passes to the East.Tuesday: No precipitation is expected. Alpine temperatures are expected to be -12.0 combined with strong NW winds.Wednesday: Continued dry and cold in the morning with light winds. In the afternoon or evening the next system should move in from the coast.

Avalanche Summary

No new avalanches reported. Some sluffing from steep terrain in the Kootenay Pass area.

Snowpack Summary

New snow combined with light winds formed some very soft slab on all aspects. The recent storm snow has not consolidated into a slab. Forecast strong winds and more new snow should create storm slabs on all aspects and at all elevations. The late November surface hoar layer that is buried down about 50 cms may be reactive in the Rossland Range with added load from the storm.

Avalanche Problems

Storm Slabs

The new storm is expected to develop a thick slab on all aspects and at all elevations. Recent light snow may also be transported by forecast strong Southwest winds into deep wind slabs on North thru East aspects.

The new snow will require several days to settle and stabilize.>Choose conservative lines and watch for clues of instability.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Persistent Slabs

Storm slab avalanches may step down and release the weak buried surface hoar layer. Avoid steep unsupported terrain features.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5