Avalanche Forecast

Issued: Nov 27th, 2014 8:06AM

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

danyelle magnan, Parks Canada

Glacier.

The Winter Permit System is now in effect. We are in the middle of a major storm. Avoid exposure to avalanche terrain.

Summary

Weather Forecast

A warm, Pacific storm hit us overnight and continues. Another 20-30cm is expected today with moderate southerly winds increasing loading rates. Freezing levels are forecast to rise, but will hopefully stay below Rogers Pass (1300m). On Friday, snowfall will start to taper off as cold, arctic air moves in. Temp's will plummet overnight 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

Avalanche activity started overnight with rapid loading by heavy snowfall and moderate winds. It's still too dark out to fully assess, but avalanches to size 3 were observed overnight. These were running well into the avalanche runout zones.

Confidence

Problems

Storm Slabs

Touchy weak layers down ~80 and ~100cm are being rapidly loaded. These layers are easily triggered and are being overloaded resulting in natural avalanches. Avalanches have been running into valley bottoms overnight.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Wind Slabs

Moderate 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.

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

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Dry

Loose avalanches are possible on steep sheltered slopes and gullies. Be cautious in these areas, where a bit of sluffing snow can quickly gain mass.

Be aware of party members below you that may be exposed to your sluffs.Watch for terrain traps where small amounts of snow will acumulate into deep deposits.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Nov 28th, 2014 8:00AM