Avalanche Forecast

Issued: Feb 2nd, 2018 4:00PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Dry and Persistent Slabs.

max darrah, Parks Canada

Jasper.

New windslabs are expected to be building overnight on Friday. Use caution moving into upper elevations.

Summary

Weather Forecast

A warm and wet airmass is colliding into a cold dry airmass along the continental divide. This is expected to produce significant snowfall, amounts for the Jasper forecast region is expected to be 10-30cm overnight on Friday. After this precipitation pulse, there will be a cooling trend and calm winds with minimal precipitation.

Snowpack Summary

40cm of recent storm snow has been pushed around by intermittently moderate to strong SW winds and created fresh windslabs in exposed areas, particularly in the alpine. In sheltered areas, this new snow sits as a touchy storm slab in many locations. Midpack persistent weak layers (Jan 16, Jan 7, and Dec 15) are still a concern but remain stubborn.

Avalanche Summary

Avalanche control on Wednesday along the Icefields Parkway produced numerous size 3 avalanches in the alpine, and many size 2-2.5 storm slab and loose avalanches at all elevations. Persistent slab avalanches were produced in the alpine where wind loaded areas provided enough of a trigger to step down to these layers.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Wind Slabs

This is the primary concern at all elevations. The new snow has settled into a touchy soft slab in many locations. This presents as a windslab in exposed areas, such as cross loaded and lee features at upper elevations.

Caution in lee and cross-loaded terrain near ridge crests.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Loose Dry

Point releases have the ability to entrain new snow and accumulate significant mass.

Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

Control work on Wednesday produced several results on this layer, particularly in the alpine where storm slabs were able to entrain enough mass to step down to mid-pack instabilities.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 3rd, 2018 4:00PM