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Archived

Avalanche Forecast

Dec 15th, 2018–Dec 16th, 2018
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
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
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Kootenay Boundary.

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

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

SATURDAY Night: Mostly dry. Freezing level down to valley floor. Light southerly winds.SUNDAY: Between a trace and 10 cm new snow. Freezing level around 1000 m. Light southerly winds around treeline, high alpine elevations could see moderate southwest wind.MONDAY: 10-20 cm new snow. Freezing level around 1500 m. Moderate southwesterly winds.TUESDAY: Continued snow with another 10 to 20 cm. Freezing level around 1500 m. Moderate southwest winds.

Avalanche Summary

Avalanches up to size 2 were reported Friday, but fewer than earlier in the week; as expected natural avalanche activity appears to be tapering off. Avalanches were running either within the storm snow or at the bottom of the storm snow where surface hoar or faceted (sugary) snow formed during the Nov / Dec drought. Remotely or explosive triggered avalanches with 50 cm crowns, on NW to NE aspects, are evidence this layer remains active.

Snowpack Summary

Approximately 50 to 60 cm of snow has fell last week, 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 and remotely triggered avalanches indicate it remains a critical layer that can release avalanches.Lower in the snowpack, previous weak layers appear inactive. These deeper layers could possibly cause problems on cold (north facing) slopes at high elevations where the snowpack is thin, but in most places, this is unlikely.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1.5 - 2.5