Avalanche Forecast

Issued: Jan 17th, 2015 4:04PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

With new snow, warming temperatures and strong W winds forecast for Sunday afternoon, it will be important to watch the local snowfall amounts and wind loading in the areas you are traveling in and reduce your exposure as the hazard increases.

Summary

Weather Forecast

A storm is forecast to arrive by mid day on Sunday bringing 10-20cm of new snow and very strong West winds at ridge top near the divide. Less snow is forecast in eastern areas. The winds ease off a little on Monday and switch to the NW with a few more cm`s of snow forecast for Monday and Tuesday. Treeline temperatures remain between -4 and -10`C.

Snowpack Summary

A trace of new snow over facets, surface hoar, or sun crust on steep South slopes. The snowpack is generally weak and facetted throughout. The Dec 18 interface is evident down 20-40 cm and is still a concern in deeper snowpack areas. In shallower areas the slab above this has facetted out. Wind slabs exist in many open areas above tree line.

Avalanche Summary

No natural avalanche activity observed in past 72 hrs.

Confidence

Intensity of incoming weather systems is uncertain on Sunday

Problems

Wind Slabs

New snow and strong W winds tomorrow afternoon will create wind slabs in open areas at tree line and above. Ice climbers should watch for sluffing in steep gullies as the new snow arrives.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Keep an eye on this layer as the new snow arrives. In shallower snowpack areas this layer has been facetting out. In deeper areas where a stronger slab exists above this layer it is more of a concern.

Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

In shallower snowpack areas (most of the region) the weak base of the snowpack persists and could be triggered in steep, rocky terrain features. This problem will persist for some time, give it careful consideration before entering serious terrain.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 18th, 2015 4:00PM