Avalanche Forecast

Issued: Apr 1st, 2018 3:48PM

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

mconlan, Avalanche Canada

Lizard-Flathead.

Snowfall amounts will vary across the region, with 30 cm possible in localized areas by Monday morning. Treat the hazard higher if more than 30 cm of new snow is found. Be cautious of overhead exposure, as cornice falls could trigger slab avalanches.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

MONDAY: Cloudy with early-morning snowfall, accumulation 10 to 20 cm and possible localized amounts around 30 cm from convective flurries, light northeasterly winds, alpine temperature -12 C, freezing level below valley bottom.TUESDAY: Partly cloudy with light snowfall, accumulation 1 to 3 cm, light westerly winds, alpine temperature -8 C, freezing level 1000 m.WEDNESDAY: Mostly cloudy, light southwesterly winds, alpine temperature -5 C, freezing level 1300 m.

Avalanche Summary

On Saturday, a large slab avalanche was triggered in the west of the region. See this MIN post for a photo and more details. A report of a small wind slab avalanche at treeline was also provided to us.

Snowpack Summary

Substantial amounts of new snowfall are expected in the region, with accumulations that could reach 30 cm in localized areas. The new snow will fall on a melt-freeze crust on sunny aspects and all aspects below 1700 m. A surface hoar and crust layer buried mid-March is found around treeline at a depth of about 70 cm, with weak surface hoar on northerly aspects and the crust elsewhere. Deeper in the snowpack, the late-November weak layer is composed of sugary facets around a crust, which is buried around 200 to 300 cm and is currently dormant.At ridgetop, cornices are large and were actively failing over the last week.

Problems

Storm Slabs

Storm slabs, as well as loose snow in sheltered areas, won't bond well to underlying surfaces and will likely be reactive. Be disciplined: observe for slab properties and the bond with the old snow surface before committing into avalanche terrain.

Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.Use ridges or ribs to avoid pockets of wind-loaded snow.Pay attention to overhead hazards like cornices, which could trigger slabs on slopes below.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Apr 2nd, 2018 2:00PM