Avalanche Forecast

Issued: Feb 28th, 2019 4:32PM

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

swerner, Avalanche Canada

Kootenay Boundary.

Wind slabs continue to be reactive to human triggers, especially on south-southwesterly aspects at treeline and above.

Summary

Confidence

High -

Weather Forecast

FRIDAY: Cloudy in Kootenay Pass with some sunshine further North around the Nelson area. Snow amounts 2-5 cm. Alpine temperatures near -7 and ridgetop winds moderate variable winds. Freezing levels near 900 m.SATURDAY: Sunny with cloudy periods. Alpine temperatures near -16 and ridgetop winds moderate from the East.SUNDAY: Sunny. Alpine temperatures near -15 and ridgetop winds light from the East.

Avalanche Summary

On Wednesday, wind slabs up to size 2 continue to be reactive to human triggers mostly from SW-W aspects. On Tuesday, a skier triggered a persistent slab avalanche on an E-SE aspect between 1680-1770 m. This is believed to have failed on the early February surface hoar/ crust interface that exists 40-60 cm down. This avalanche was 100 m wide and ran 300 m in length.

Snowpack Summary

New snow 10-15 cm adds to 25 cm from last weekend. Strong northeast winds have redistributed the recent snow, loading leeward slopes and cross-loading slopes at all elevations. The wind slabs are most reactive to the weight of a person on southerly slopes. The upper snowpack now covers variable old wind slabs at higher elevations and sun crusts on south-facing slopes. A weak layer of surface hoar crystals and a crust that was buried on February 7th is now 30-50 cm deep. This layer has been reactive to human triggers up to size 2. Two other surface hoar layers are buried 50 to 80 cm deep the snowpack (referred to as the February 1st and mid-January layers) and continues to be reactive to human triggers. The mid-pack is complex and requires diligence and patience. The lower snowpack is considered generally strong.This MIN report reflects the Kootenay Pass area well. This MIN report reflects the Bonnigton Range.

Problems

Wind Slabs

Northeast winds have formed fresh and reactive wind slabs on southerly slopes and terrain features. Old, buried wind slabs also linger on a variety of aspects. Loose dry sluffing may exist on steep slopes and terrain features with the recent snow.

Use caution in freshly wind-loaded features, especially near ridge crests and in steep terrain.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

It remains possible to trigger an avalanche on one of the surface hoar or crust layers buried 30 to 80 cm deep. These layers are most prominent around treeline elevations.

Use increased caution on open slopes and convex rolls at lower elevations.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Caution around sheltered open areas at treeline and below including cutblocks, gulleys, and glades.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Mar 1st, 2019 2:00PM