Avalanche Forecast

Issued: Dec 14th, 2018 5:19PM

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

jfloyer, Avalanche Canada

Kootenay Boundary.

A Special Public Avalanche Warning is in effect for this region. The mountains are still primed for human-triggered avalanches, especially at higher elevations.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

FRIDAY NIGHT: 10-15 cm new snow, falling as rain below 1700 m. Strong southerly winds.SATURDAY: Mostly dry. Freezing level around 1000 m. Moderate southwesterly winds. SUNDAY: 5-10 cm new snow. Freezing level around 1500 m. Strong southerly winds.MONDAY: 10-15 cm new snow. Freezing level around 1500 m. Moderate southwesterly winds.

Avalanche Summary

Numerous natural and explosives triggered avalanches to size 2 were reported in the region on Wednesday. Expect the storm slab to remain reactive with high freezing levels and strong winds.

Snowpack Summary

Approximately 50 cm of recent storm snow has fallen in the region with strong southerly winds. This snow sits on top of a weak layer of facets (sugary crystals), surface hoar (feathery crystals) and a sun crust on south aspects. Recent "sudden" snowpack test results on this layer indicate it still has the potential to release avalanches.Lower in the snowpack there were a couple of previous weak layers in the middle of the snowpack that appear to have become inactive, and a layer of sugary facets near the base of the snowpack. This latter layer could possibly cause problems on cold (north facing) slopes at high elevations where the snowpack is thin, but in most places, this is unlikely.

Problems

Persistent Slabs

A weak layer buried around 50 cm is causing concern. This concern is heightened on steep slopes where wind has drifted snow into a reactive slab.

Watch for whumpfing, hollow sounds, and shooting cracks.Choose low angle and supported terrain and watch for clues of instability.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Wind Slabs

Recent new snow and strong winds have set up wind slabs in exposed areas, particularly on north to east aspects.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 15th, 2018 2:00PM