Avalanche Forecast

Issued: Feb 28th, 2018 4:44PM

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

jmcbride, Avalanche Canada

Northwest Inland.

New snow and strong wind Wednesday night and Thursday will create storm slabs at upper elevations. Be especially wary of wind-loaded, leeward and cross loaded slopes.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

TONIGHT: Flurries. Accumulation 5-10 cm. Ridge wind strong to extreme, southeast. Temperature near -8. Freezing level valley bottom.THURSDAY: Cloudy, Flurries. Accumulation 5-10 cm. Ridge wind strong, east. Temperature near -10. Freezing level valley bottom.FRIDAY: Mix of sun and cloud. Ridge wind moderate, east. Temperature near -14. Freezing level valley bottom. SATURDAY: Sunny. Ridge wind light, east. Temperature near -10. Freezing level valley bottom. Alpine inversion.

Avalanche Summary

Tuesday there were reports from northern parts of the region of loose dry storm snow releases up to size 1.5 in steep terrain as well as a skier triggered storm slab (size 1) on steep, southeast-facing, roll that failed on a buried sun crust.On Monday there was a report of a natural size 2 storm slab release on a east aspect below treeline feature that failed on facets buried by recent storm snow. Skiers also reported triggering small storm slab releases on steep convex rolls below treeline.With continued moderate to strong westerly winds it's likely that recent snow and wind loading at treeline and alpine elevations has primed conditions for human-triggering or natural avalanches.

Snowpack Summary

Light snow and strong winds continue to create wind slabs in open terrain at alpine and treeline elevations. These cover old hard wind slabs and scoured surfaces in many exposed areas. In wind-sheltered terrain, sun crusts or dry facets sit below the recent storm snow.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 could possibly be triggered from shallow snowpack areas.

Problems

Storm Slabs

New snow and strong wind will form slabs at upper elevations and on open features at and below treeline. Expect these slabs to be sensitive to light triggers and could be easily triggered by the weight of a person.

Give cornices a wide berth when travelling on or below ridges.Avoid lee areas in the alpine and treeline. Storm snow and wind will form touchy slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very 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

Valid until: Mar 1st, 2018 2:00PM