Avalanche Forecast

Issued: Nov 19th, 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.

ian jackson, Parks Canada

Banff Yoho Kootenay.

Conditions are generally pretty good out there, but we are still getting occasional reports of whumphing and larger avalanches. The majority of the recent avalanche activity has been in the Sunshine and Lake Louise ski area backcountry

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 0 to -4C at treeline. Some light precipitation may be coming in on Thursday, but we'll see....

Snowpack Summary

15-30 cm of facetted surface 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

Avalanche activity seems to be more active around the local ski hills than in the Icefields Parkway area, but is tapering in general. Sunshine was reporting 2 x size 2 natural avalanche on steep south facing alpine terrain with the first sun on Monday. Otherwise, just observations from Sunday including a size 2 in Pipestone bowl in Lake Louise.

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.

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

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

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.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 2.5

Valid until: Nov 20th, 2018 4:00PM