Avalanche Forecast

Issued: Jan 13th, 2017 4:08PM

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

Avalanche Canada shorton, Avalanche Canada

The incoming storm will load a weak snowpack and create very dangerous avalanche conditions.

Summary

Confidence

High -

Weather Forecast

FRIDAY NIGHT: 5-15 cm of new snow, strong southwest winds, alpine temperatures rising to -5 C.SATURDAY: Another 10-25 cm of new snow with greater accumulations in the north, strong to extreme southwest winds at ridgetop, alpine temperatures around -3 C.SUNDAY: A break in the storm with flurries, sustained strong southwest winds, freezing level around 1000 m.MONDAY: Stormy with 15-25 cm of new snow, extreme southwest winds at ridgetop, freezing level around 1200 m.

Avalanche Summary

Deep persistent slab avalanches continue to be reported in the Ningunsaw area, including natural and explosive triggered size 2.5 avalanche running on basal facets on southwest aspects. A natural size 2 wind slab avalanche was reported in the southern part of the region on Thursday, releasing on a wind-loaded northeast alpine slope.With the incoming storm expect an increase in avalanche activity, including very touchy storm slabs that have the potential to trigger large deep persistent slab avalanches.

Snowpack Summary

On Saturday, expect 15-40 cm of new snow, which combined with warming temperatures and strong winds will form a widespread storm slab problem. Storm slabs will be extra thick and touchy on wind-loaded features. The new snow is burying a layer of feathery surface hoar crystals, which will allow for wide propagations in the storm snow. Snow depth at treeline varies from about 1 m in most areas to 2 m in deeper snowpack areas in the south and west of the region. The shallow snowpack areas mostly consist of weak faceted or sugary grains beneath hard slabs. With the additional load of the new snow these hard slabs may produce surprisingly long fractures resulting in large avalanches, and in some instances they may step down to weak faceted snow crystals near or at the ground.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Loading and warming will increase the likelihood of triggering deep persistent slabs throughout the weekend and beyond.
Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Storm Slabs

An icon showing Storm Slabs
New snow, warming temperatures, and strong winds will create a widespread storm slab problem. Small storm slabs are likely to step down to deeper persistent slabs.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 2

Valid until: Jan 14th, 2017 2:00PM