Archived

Avalanche Forecast

Mar 18th, 2017–Mar 19th, 2017

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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Time to be extra cautious in avalanche terrain. Deep weak layers are under stress and have been producing large avalanches recently.

Confidence

Moderate -

Weather Forecast

SUNDAY: Sunny, moderate northwest winds, alpine temperatures around -8 C.MONDAY: Mix of sun and cloud, light winds, alpine temperatures around -5 C.TUESDAY: Afternoon flurries with 5-10 cm, light southwest winds, freezing level climbing to 1500 m with alpine temperatures around -2 C.

Avalanche Summary

Initial reports from Saturday include numerous natural and skier triggered loose wet avalanches at lower elevations (size 1.5) . Reports from Friday include several large natural avalanches including a size 3 persistent slab in the Rossland range and up to size 3.5 deep persistent slabs in the Valhallas (failing on basal facets over 2 m deep).The upper snowpack should stabilize with cooler temperatures, but deeper persistent weak layers remain under heavy stress and have the potential for large and surprising avalanches.

Snowpack Summary

Rain has soaked the upper snowpack for a second time in a week. This time all the way to mountain tops. Cooling temperatures will gradually form a rain crust on the surface, but expect a thick layer of moist snow in the upper snowpack for some time. This heavy snow will stress a number of deeper weak layers including the late-February facet / surface hoar interface (70-120 cm deep), the mid-February crust (90-130 cm deep), and basal facets in shallow snowpack areas.

Avalanche Problems

Persistent Slabs

Deep weak layers are under heavy stress after recent loading and warming, creating the potential for large and surprising avalanches.

Use careful route-finding and stick to moderate slope angles with low consequencesAvoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 4