Avalanche Forecast

Issued: Jan 5th, 2014 8:37AM

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

mbender, Avalanche Canada

Cariboos.

Complex avalanche conditions at the moment. The answer to this type of avalanche problem lies in conservative terrain selection.

Summary

Confidence

Fair - Freezing levels are uncertain on Monday

Weather Forecast

A strong, stable northwesterly flow will prevail over the province while a strong upper ridge remains offshore. The ridge should weaken somewhat on Tuesday but will still protect the province from Pacific systems.Monday: Mainly dry conditions, freezing level at valley bottom with a chance of a temperature inversion bringing warmer temperatures to upper elevations. Temperatures approaching 0 degrees or slightly warmer between 2000 and 2800m. Winds moderate to strong from the west and northwest.Tuesday: Mainly cloudy, no precipitation, alpine temperatures -8, 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.

Avalanche Summary

Reports continue to indicate a natural and explosives triggered avalanche cycle that occurred on Thursday and Friday up to size 3.5. 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. Wind slabs were running naturally on all aspects to size 2. These were mostly isolated to the storm snow.

Snowpack Summary

Thursdays 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. The last week has brought around a meter of snow.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 Friday's avalanche cycle. 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, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

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.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>Choose well supported terrain without convexities and avoid slopes with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 6th, 2014 2:00PM