Avalanche Forecast

Issued: Feb 23rd, 2018 3:45PM

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

pgoddard, Avalanche Canada

Northwest Inland.

Ongoing winds will shift any available snow into variable wind slabs. Back off if you encounter drummy, hollow snow, whumpfing or recent avalanche activity.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY: 5-10 cm snow. Freezing level at valley floor. Moderate south-westerly winds. SUNDAY: A mix of sun and cloud with flurries possible. Freezing level near 400 m. Light to moderate westerly winds.MONDAY: Flurries. Freezing level near 400 m. Strong south-westerly 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

Light snow and strong winds over the weekend are building wind slabs in open terrain at alpine and treeline elevations. These overlie buried old hard wind slabs, scoured surfaces and sastrugi in many exposed areas. In wind-sheltered terrain, sun crusts or dry facets sit below the recent storm snow.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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Valid until: Feb 24th, 2018 2:00PM