Archived

Avalanche Forecast

Mar 19th, 2017–Mar 20th, 2017

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

1: Low

The avalanche danger rating below treeline will be low

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

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

Regions: Kootenay Boundary.

Although there has been has been a significant crust forming at most elevations it is recommended to employ a cautious approach at upper elevations where the latest storm only produced snow.

Confidence

Moderate - Freezing levels are uncertain on Wednesday

Weather Forecast

MONDAY: Mix of sun and cloud / Light east wind / Alpine temperature -3 / Freezing level 1400mTUESDAY: Cloudy with scattered flurries / Light east wind / Alpine temperature -1 / Freezing level 1500mWEDNESDAY: Flurries, accumulation 5cm / Light to moderate southwest wind / Alpine temperature 1 / Freezing level 1900m

Avalanche Summary

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 when crust form or reform, 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 have formed 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.

Be aware of thin areas that may propogate to deeper instabilites.If triggered the smaller avalanches may step down to deeper layers resulting in large avalanches.Be alert to conditions that change with elevation.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3

Loose Wet

If the sun comes out expect whatever snow that fell this weekend at uppermost elevations to sluff from steep solar aspects. A smaller avalanche could act as a trigger for the deeper buried weak layers.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2