Avalanche Forecast

Issued: Jan 6th, 2016 7:47AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs and Cornices.

triley, Avalanche Canada

South Columbia.

Continued new snow and wind will bump the alpine danger up to Considerable. Watch for natural cornice falls and remote triggering of wind slabs.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Thursday

Weather Forecast

Some moisture trapped in the south to north flow coming out of Washington State should bring 3-5 mm of precipitation (5-10 cm of snow at treeline) overnight, and another 5-7 mm of precipitation during the day on Thursday. Some of the western upslope areas may see enhanced snowfall. Winds are expected to be light from the southeast and alpine temperatures should remain around -5. High pressure with light winds and cooler air should move into the region from the north on Friday. Some flurries may continue on Friday and Saturday with periods of broken skies and alpine temperatures around -10.

Avalanche Summary

Natural cornice avalanches and natural and skier controlled wind slab avalanches up to size 1.5 have been reported. Most of these have been on northerly aspects in the lee of local winds. Winds have been generally easterly, but some areas have had locally more southerly winds due to terrain.

Snowpack Summary

10-25 cm of new snow is now sitting on the mix of surface hoar, near surface facets, and sun crust that was left behind after the recent clear and warm weather. Easterly winds have transported the new snow and some of the loose snow available into wind slabs at higher elevations. The new snow is reported to be loose and unconsolidated except where the wind slabs exist. Forecast warming with continued light snow may settle the storm snow into a cohesive slab. The mid and lower snowpack is generally well settled and strong.

Problems

Storm Slabs

Wind slabs continue to develop. Winds are mostly light to moderate, but have been reported to transport loose snow at treeline and above. Warming temperatures may help consolidate wind transported snow into a cohesive storm slab.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Fresh cornice growth may be fragile and easy to trigger. Some natural cornice fall is expected with continued snow and wind.

Extra caution needed around cornices with current conditions.>Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Jan 7th, 2016 2:00PM