Avalanche Forecast

Issued: Mar 2nd, 2017 4:04PM

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

swerner, Avalanche Canada

Northwest Inland.

Wind slabs are more reactive in locations West of Hankin-Evelyn and the Telkwa due to higher snowfall amounts and stronger ridgetop winds.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: Mix of sun and cloud with a trace of new snow. Ridgetop winds light from the South and alpine temperatures near -9.Saturday: Mostly cloudy with isolated flurries. Ridgetop winds light from the SE and alpine temperatures -10. Sunday: Cloudy with sunny periods and an alpine high of -12.

Avalanche Summary

On Wednesday, numerous natural storm slabs up to size 1.5 were reported from the western part of the region and no avalanche activity reported from the Telkwa riding locations. Isolated wind slabs may be found in alpine locations on leeward slopes.

Snowpack Summary

Recent low density storm snow up to 25 cm has fallen with surprisingly little wind effect. The new snow has buried a variety of old snow surfaces including stiff wind slabs, facets, crusts and surface hoar. The new snow may have a poor bond to these interfaces. At treeline elevations the average snowpack depths are 120-190 cm and a well consolidated mid-pack of approximately up to 100 cm sits above weak basal facets (sugary snow) near the ground. Recent snowpack testing has shown sudden easy results down 25 cm on a surface hoar layer and sudden hard results down 100 cm within the facetted snow. The deeper basal weakness remain a concern, especially from thin rocky start zones and shallower snowpack locations.

Problems

Wind Slabs

Gusty SW winds at upper elevations have formed fresh wind slabs on leeward slopes and behind terrain features. Loose dry avalanches may be easily triggered below treeline or in areas sheltered from the wind.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

A lingering weakness at the bottom of the snowpack may remain sensitive to human triggering, especially in shallow snowpack areas. Smaller avalanches in motion also have the potential to step down and trigger deep persistent slabs.

Avoid steep convexities or areas with a thin or variable snowpack.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 4

Valid until: Mar 3rd, 2017 2:00PM