Avalanche Forecast

Issued: Feb 21st, 2018 4:04PM

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

swerner, Avalanche Canada

South Coast.

Wind slabs remain reactive to human triggers. Pay attention to overhead hazards like cornices, especially when the sun is out.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

Thursday: Mostly sunny with treeline temperatures near -2 and freezing levels 500 m. Ridgetop winds light from the North.Friday: Overcast with new snow amounts 5-15 cm. Treeline temperatures near -2 and ridgetop winds strong from the South. Saturday: Mix of sun and cloud. Treeline temperatures near -2 with freezing levels 600 m. Light to moderate winds from the northwest.

Avalanche Summary

On Tuesday, several natural wind slab avalanches were reported from all aspects up to size 2. Although a couple of them were fresh, the bulk of them were up to 72 hours old. Natural avalanche activity is tapering, but human triggered slabs that sit above the buried crust remain possible.

Snowpack Summary

Surface snow is highly variable and wind-affected. In exposed terrain, strong north winds have scoured north facing slopes and loaded south facing slopes. In sheltered terrain, cold weather is preserving 30-50 cm of low density snow. A hard rain crust that extends into alpine terrain is buried about 40 cm beneath the recent storm snow. Reports suggest the snow has a poor bond to the crust with test results showing sudden planar characteristics and it remains reactive to human triggers. Monitor the bond of the snow to this crust closely. There are no significant layers of concern below the crust.

Problems

Wind Slabs

Strong northerly winds from several days past have formed stiff wind slabs. Wind slabs remain reactive to human triggers, especially where they sit on a buried crust. Loose dry sluffing is likely from steeper terrain features.

Use ridges or ribs to avoid pockets of wind loaded snow.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect, especially if the sun is shining.

Give cornices a wide berth when traveling on or below ridges.Firm cornices may pull back into flat terrain at ridgetop if they fail.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Feb 22nd, 2018 2:00PM