Avalanche Forecast

Issued: Feb 22nd, 2018 3:57PM

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

pgoddard, Avalanche Canada

Northwest Inland.

Watch for wind slabs on a variety of slopes at treeline and alpine elevations.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Friday

Weather Forecast

FRIDAY: 2-10 cm snow. Freezing level near 500 m. Moderate to strong westerly winds. SATURDAY: Light snow. Freezing level near 300 m. Moderate winds. SUNDAY: Flurries. Freezing level near 600 m. Moderate winds.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

Rapid wind loading caused a natural avalanche cycle to size 2.5 on Wednesday. With ongoing moderate to strong winds forecast, wind slabs will remain possible to trigger over the next few days. Persistent slabs could still be triggered from thin-to-thick snowpack areas, or with a heavy load like a cornice fall.

Snowpack Summary

The snowpack has gone through several bouts of fighting with strong to extreme northerly winds in the last week. You are likely to encounter wind slabs in many places. Variable surface conditions include fragile cornices, hard and soft wind slabs, and scoured surfaces. The wind slabs sit on various old surfaces including sun crusts, facets and spotty surface hoar (which is most prevalent in sheltered treed locations). Around 50-150 cm down, you will find a crust/surface hoar layer from mid-January, which still has the chance to surprise you and could be triggered from a thin snowpack spot, or with a large trigger like cornice fall. Facets at the base of the snowpack can possibly be triggered from shallow snowpack areas.

Problems

Wind Slabs

Wind slabs are widespread and could be triggered by the weight of a person.

Travel on ridgetops to avoid wind slabs on slopes below.Give cornices a wide berth when travelling on or below ridges.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Persistent Slabs

Buried weak layers are most likely to be triggered from thin or variable depth snowpack areas; or with a large load like a cornice fall.

Avoid thin, rocky or sparsely-treed slopes.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Valid until: Feb 23rd, 2018 2:00PM