Avalanche Forecast

Issued: Feb 3rd, 2017 4:00PM

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

Tim Haggarty, Parks Canada

Banff Yoho Kootenay.

Snowfall amounts are uncertain this weekend but if a significant amount arrives expect avalanche activity on the deep persistent layer.

Summary

Weather Forecast

A low over the coast is spreading a stream of moisture to the Southern Rockies while competing polar air overlies our forecast area. The amount of snow that arrives depends on which of these two air masses is the strongest and where the boundary between them ends up varying between 10 and 30cm. Temps and winds will be equally difficult to predict.

Snowpack Summary

Previous strong to extreme W winds have created harder wind pressed surfaces at treeline and above. Surface hoar may be found buried in sheltered locations. Generally the midpack is weak at TL and above, and the entire snowpack is weak BTL. Near the divide, deeper snow-packs are a bit stronger and more supportive.

Avalanche Summary

We had a small avalanche cycle this past weekend due to big winds, but as temperatures have cooled and winds abated, the activity has slowed down significantly. No new avalanches reported or observed Thursday or Friday.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Saturday

Problems

Deep Persistent Slabs

The snowpack is weak. Slopes where a slab sits over the deeper weak layers should be treated as suspect. Increasing load and further slab development will make these slabs more sensitive through the weekend.

Be aware of thin areas that may propogate to deeper instabilites.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Feb 4th, 2017 4:00PM