Avalanche Forecast

Issued: Mar 9th, 2017 5:48PM

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

jlammers, Avalanche Canada

Northwest Inland.

The best and safest riding may in lower elevation terrain sheltered from the wind.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: Mainly clear skies / Moderate easterly winds / Alpine temperature of -18Saturday: Overcast skies with light flurries / Moderate easterly winds / Alpine temperature of -15Sunday: 5-15cm of new snow / Moderate southerly winds / Alpine temperature of -9

Avalanche Summary

A size 2 natural wind slab was observed in the southwest corner of the region on Wednesday failing on a north facing slope at about 1600m. Wind slab activity will likely increase on Friday in response to strong southeast winds redistributing loose surface snow. Surface wind slabs will have the potential to step down to deeper, more destructive layers.

Snowpack Summary

Generally light daily amounts of low density snow have fallen in recent days. Strong and variable winds have likely formed wind slabs on a variety of aspects in exposed terrain. These daily accumulations have incrementally loaded a weak interface which was buried in February. This buried layer includes stiff wind slabs, facets, crusts and surface hoar. The overlying slab may have a poor bond to these interfaces, especially in areas where the slab may be stiffer and more cohesive due to winds. At treeline, 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. The deeper basal weakness remain a concern, especially in thin rocky start zones and shallow snowpack locations..

Problems

Wind Slabs

Gusty winds from the southwest, and more recently the southeast, have formed fresh wind slabs on a variety of aspects. Wind slab reactivity may persist for longer than usual due to underlying persistent weaknesses.

Use ridges or ribs to avoid pockets of wind loaded snow.Sheltered slopes will likely offer the best and safest riding today.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

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 destructive deep persistent slabs.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 10th, 2017 2:00PM