Avalanche Forecast

Issued: Mar 24th, 2018 4:11PM

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

swerner, Avalanche Canada

Lizard-Flathead.

Up to 35 cm of recent storm snow is being redistributed by the predominant southwest wind will likely build thicker, reactive slabs on leeward slopes. If the sun pokes out it may initiate a natural avalanche cycle in the recent storm snow.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

Sunday: Mix of sun and cloud with possible snow amounts 2-5 cm. Ridgetop wind strong from the southwest. Alpine temperatures near -4 and freezing levels 1300 m. Monday: Cloudy with sunny periods. Ridgetop wind strong from the southwest. Alpine temperatures near -4 and freezing levels 1300 m. Tuesday: A mix of sun and cloud. Ridgetop winds strong from the southwest. Freezing levels 1300 m.

Avalanche Summary

Cornice control work showed numerous size 1-2 avalanches on north through southeast ridgelines. above 1900m. The cornice failures produced mostly loose dry avalanches from the slopes below with a few smaller slabs only releasing in the storm snow. On Friday, numerous natural storm slab avalanches were reported from North aspects above 1700 m. Periods of sunshine forecast for Sunday could trigger a round of natural slab avalanches and loose dry/wet avalanches.

Snowpack Summary

Up to 40 cm of recent storm snow will initially have a poor bond to the plethora of old snow surfaces including a melt-freeze crust on sunny aspects and all aspects below 1600 m, surface hoar on north aspects above 1600 m. Wind slabs are building on most aspects due to the changing winds and overhanging cornices exist along ridgelines. Deeper in the snowpack, the mid-December and late-November weak layers are composed of crusts and sugary facets, which are down 150-300 cm. These layers are currently dormant.

Problems

Wind Slabs

Changing winds from East-West continue to be strong, redistributing the recent storm snow onto most aspects. Wind slabs will likely be reactive to skier/rider triggers. Loose dry avalanches may occur from steeper terrain features.

Wind slabs may be more reactive where they sit on a buried crust or surface hoar interfaceAvoid large slopes and convex features.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Cornices

Large looming cornices exist across ridgelines. Cornices are unpredictable and demand respect. They're more likely to fail during wind events or when the sun comes out.

Pay attention to overhead hazards like cornices which could trigger a slab from the slope below.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Mar 25th, 2018 2:00PM