Avalanche Forecast

Issued: Nov 18th, 2018 4:00PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Good skiing can be found in sheltered areas following the strong winds on Saturday night. Keep an eye out for wind slab development as a result of these winds, and keep checking the bond around the Oct 26 crust if you venture into bigger terrain.

Summary

Weather Forecast

Clear weather is expected for the next couple days with light to moderate SW winds. Overnight lows of -12 to -14C with daytime highs of -2 to -4C at treeline.

Snowpack Summary

15-30 cm of recent storm snow. Wind effect at treeline and above scouring exposed ridge crests and building wind slabs in the alpine, especially in our eastern forecast regions. The Oct 26 crust is roughly 30 cm above the ground with facets above and below it. It is present up to 2800m on shady aspects, and at higher elevations on solar aspects.

Avalanche Summary

Several explosive triggered wind slabs up to size 2.5 were reported today at the Sunshine ski area following moderate to strong NW winds overnight. These failed on the October 26 crust and ran a long distance. Natural activity has been minimal in the last couple days with some wind triggered sluffs in steep terrain and isolated smaller slabs.

Confidence

Due to the number of field observations

Problems

Wind Slabs

The wind slab problem seems to be most active in Eastern areas where greater amounts of recent storm snow were available to be moved around by the wind.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered the wind slabs may step down to deeper facet layers resulting in larger avalanches.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Deep Persistent Slabs

We are seeing occasional explosive controlled avalanches on the Oct 26 crust at local ski areas, failing on facets either above or below the crust, but little natural or skier triggered activity. The lower likelihood makes it a bit hard to predict.

If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.Whumpfing is direct evidence of a buried instability.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Nov 19th, 2018 4:00PM