Avalanche Forecast

Issued: Nov 28th, 2014 8:13AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Wind Slabs.

danyelle magnan, Parks Canada

Glacier.

The Winter Permit System is in effect. Natural avalanche activity will decrease this weekend but conditions are still touchy. Don't let the sun lure you into bigger terrain. Human triggered avalanches are likely. Stick to simple, low angle slopes.

Summary

Weather Forecast

The warm, moist storm system that been hammering us will exit the region today. Rain should change back to snow, we may get another 10cm at higher elevations today, and winds should ease. Following the storm, an arctic high moves in and temperatures will plummet.. Saturday and Sunday will be clear and cold, with temps ranging from -18 to -28'C.

Snowpack Summary

Two layers of concern, the Nov 21 surface hoar/sun crust layer down ~ 90 and Nov 9 rain crust down ~110cm, are becoming reactive as the load on top of them increases. Snowpack tests in two locations, a south aspect and a north aspect, showed that these layers may be triggered by skiers and if triggered are likely to propagate into large avalanches.

Avalanche Summary

A large avalanche cycle occurred yesterday with natural avalanches occurring on all aspects, flattening the alder on avalanche fans. Along the highway corridor 28 size 2-2.5's, 9 size 3's and 2 size 3.5 avalanches were observed yesterday. As temperatures and freezing levels rose the avalanches became wet in character.

Confidence

Problems

Storm Slabs

Snow, wind and now rain have been rapidly loading touchy weak layers down ~80 and ~100cm. These layers are easily triggered (see details) and have been producing very large, natural avalanches.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Wind Slabs

Moderate to strong southerly winds are loading lee slopes and forming more cohesive slabs. Wind loading will also trigger natural avalanches. Avoid exposure to steep paths that are being rapidly loaded, such as the Cheops North paths.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Valid until: Nov 29th, 2014 8:00AM