Avalanche Forecast

Issued: Jan 6th, 2014 8:29AM

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

mbender, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain on Thursday

Weather Forecast

The high pressure system of late weakens and gives way to a series of Pacific frontal systems.Tuesday: Mainly cloudy, no precipitation, alpine temperatures -8, moderate northwest easing to light west winds.Wednesday: A Pacific frontal system starts to affect the interior regions. Cloudy with light snowfall, moderate to strong west winds. Freezing level in the valley bottom.Thursday: Light snowfall, Alpine temperatures -7, moderate west winds.

Avalanche Summary

Reports continue to roll in about the extent of the avalanche cycle from last Thursday and Friday. The larger of the explosives triggered avalanches were mostly running on north through east facing slopes at upper elevations and involved the basal weaknesses near the ground up to size 3.5. More recent avalanche activity seems to be isolated to a few windslab releases up to size 2.5. These are running within the storm snow in the alpine and at treeline elevations.

Snowpack Summary

Last week's storm brought 25 - 60 cm of snow to the region. This snow lies on top of old wind slabs, a buried rain crust that exists below 1600m and a surface hoar or facet layer that is down 100-150cm deep. Snowpack depths vary, but in general 175 cm of snow can be found at treeline, with 125-300 cm in the alpine. In some places we're still dealing with a relatively thin snowpack (thanks to a windy early season). The basal facet/crust combo (weak sugary snow above and below a crust) near the ground was active in an avalanche cycle last Thursday and Friday. This weakness may be difficult to trigger but if triggered, will result in very large, destructive avalanches.

Problems

Wind Slabs

Recent snowfall and moderate to strong winds have created winslabs on a variety of aspects. Triggering a windslab could add a significant load to the snowpack and possibly step down to a deeper buried persistent weak layer.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

The presence of persistent weak layers increases the likelihood of larger avalanches that could release to the depth of a meter or even to the ground. The distribution and reactivity of persistent weak layers is highly complex at this time.

Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>If your sled is bogging down in avalanche terrain, spinning the track may increase the chance of triggering a buried weak layer.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 7th, 2014 2:00PM