Avalanche Forecast

Issued: Jan 13th, 2015 4:13PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Flights in the park today again showed evidence avalanche activity - up to size 3 in the last 36 hours. We remain concerned for human triggering on all steep start zone areas at higher elevations.

Summary

Weather Forecast

The forecast calls for warmer temperatures tomorrow (-5C in the alpine), but the cloud cover and light west winds should keep things from getting too warm. Temperatures will cool Thursday and the winds will pick up as the next skiff of snow arrives on Friday.

Snowpack Summary

Wind slabs are present in many open areas above tree line. Below this, the snow pack is quite weak and facetted in most places. The Dec 18 crust/facet/surface hoar interface is down 30-40cm at tree line. Backcountry users are experiencing widespread of whumphing on this layer. The bottom half of the snow pack consists of facets and depth hoar.

Avalanche Summary

Flights over the park today with good visibility revealed a widespread natural avalanche cycle over the past few days. Wide propagations at treeline and above up to size 3, many running to the bottom of the runout zones.

Confidence

Problems

Persistent Slabs

This is a serious weak layer down 40 cm that seems to be either crust, facets or surface hoar depending on location. Snowpack tests continue to be in the moderate and sudden range for this layer, indication strong potential for human triggering.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Deep Persistent Slabs

In shallower snowpack areas (most of the region) the weak base of the snowpack persists and can be triggered in steep, rocky terrain features. Patience is a virtue with this problem, as bigger terrain may not be available until later this winter.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 14th, 2015 4:00PM