Avalanche Forecast

Issued: Jan 26th, 2016 8:13AM

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

triley, Avalanche Canada

Cariboos.

Strong winds and rising freezing levels are pushing the danger ratings up. Conservative terrain choices without overhead hazards are recommended at this time.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Cloud and flurries should continue overnight, combined with strong southwest winds and rising freezing levels. Flurries or light snow on Wednesday with strong southwest winds and freezing levels rising up to about 2200 metres. Moderate to heavy snowfall on Thursday with winds gradually decreasing and freezing levels dropping below 1500 metres. Light westerly winds on Friday combined with an overnight freeze down to valley bottoms and periods of light snow.

Avalanche Summary

One size 1.5 natural avalanche was reported on Monday. On Sunday, a skier remotely trigger a size 1 avalanche on a NW aspect from 10m away. The slab was 60cm thick which suggests that it failed on the early January surface hoar layer. Natural loose avalanches up to size 2 were also reported from extreme terrain and did not trigger any slabs below. Widespread natural avalanche activity up to size 3 was reported on Friday and Saturday. The majority of this activity occurred on the early January surface hoar layers and the slabs typically varied from 70-120cm thick. There are also several great Mountain Information Network posts in the Cariboos from the weekend which you should check out. Natural activity tapered off since Saturday but the persistent slab is expected to remain reactive to human triggering for several more days.

Snowpack Summary

New wind slabs are developing in the alpine and at treeline. Wind slabs and recent storm slabs have added load and stress to the already volatile persistent slab. There are a couple of highly reactive layers of surface hoar typically down 70-100cm which have been responsible for numerous recent large avalanches. The persistent slab is ripe for human and natural triggers and is especially touchy at and below treeline. The mid and lower snowpack below these layers is generally well-settled and strong, with any old weak layers considered dormant for now. Snowpack depths are variable and shallow snowpack areas may have weak facetted crystals near the ground.

Problems

Persistent Slabs

The slab above the persistent weak layer continues to be touchy, releasing naturally or with light additional loads like a single skier on adjacent terrain. Conservative terrain choices without overhead hazard are recommended at this time.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar. >Extra caution required in open terrain features at and below treeline. >Use conservative route selection and be aware of the potential for remote triggering. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

Forecast strong winds and new snow are expected to continue to develop wind slabs in the alpine and at treeline. Rising freezing levels may increase the likelihood of triggering these wind slabs.

Be cautious as you transition into wind affected terrain. >Avoid freshly wind loaded features. >Use ridges or ribs to avoid pockets of wind loaded snow. >

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Jan 27th, 2016 2:00PM