Avalanche Forecast

Issued: Apr 7th, 2018 4:30PM

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

jmcbride, Avalanche Canada

Northwest Inland.

Strong winds have formed widespread wind slabs at upper elevations. Just how reactive these slabs are however, is a bit unknown. Be cautious in lee areas, start with small, low consequence features before working your way into bigger terrain.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TONIGHT: Mostly cloudy, light flurries. Accumulation trace. Ridge wind light to moderate, southeast. Alpine temperature near -5. Freezing level 500 m.SUNDAY: Mix of sun and increasing cloud. Ridge wind moderate, southwest. Alpine temperature near -2. Freezing level 1500 m. MONDAY: Cloudy, light flurries. Accumulation trace. Ridge wind moderate to strong, southwest. Alpine temperature near -2. Freezing level 1500 m.TUESDAY: Cloudy, flurries. Accumulation 4-8 cm. Ridge wind strong to extreme southeast. Alpine temperature near -2. Freezing level 1500 m.

Avalanche Summary

A widespread natural avalanche cycle (up to size 2), triggered by intense wind loading was reported from the northern part of region on Thursday.A natural, solar triggered size 2 avalanche was reported on Wednesday morning in the Howson range, as well as skier triggered size 1 storm slab releases on a buried sun crust (30 cm deep) on a southeast aspect at 1700 m.

Snowpack Summary

From 20 cm up to 50 cm of recent storm snow is being redistributed by strong winds and sits above a variety of crusts on all but high north aspects.Weak layers buried around March 19th are roughly 40 cm below the surface (up to 100 cm in deeper snowpack areas). These weak layers include surface hoar on shaded aspects at high elevations and hard crust layers on solar aspects and below treeline.Near the bottom of the snowpack, weak and sugary facets are found in shallow, rocky snowpack areas. Storm slabs have stepped down to these facets and producing very large avalanches in northern parts of the region.

Problems

Wind Slabs

Strong to extreme winds have created touchy wind slabs on leeward and cross-loaded slopes at treeline and above. While natural activity has tapered off, these slabs may remain primed for human triggering.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded areas, especially near ridge crests and roll-overs.Pay attention to overhead hazards like cornices which may become fragile with daytime warming.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Loose Wet

Recent storm snow may become unstable due to rising freezing levels and solar radiation. Watch for moist or wet snow releases at lower elevations and on sunny slopes.

Be increasingly cautious on sun exposed slopes.Use extra caution on slopes if the snow is moist or wet.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 8th, 2018 2:00PM