South Columbia

New snow and wind will add load to an already unstable snowpack. Choose low angle terrain and avoid exposure to overhead hazard.

Moderate - Intensity of incoming weather systems is uncertain

SUNDAY NIGHT -Flurries, 5-15 cm / south to southwest winds, 25-50 km/h / alpine low temperature near -4MONDAY - Cloudy with flurries, 5-15 cm / southwest winds, 25-50 km/h, gusting to 65 km/h / freezing level 1500 m / alpine high temperature near -5TUESDAY - Snow, 15-30 cm / southwest winds, 30-50 km/h / freezing level 1400 m / alpine high temperature near -4, low temperature near -6WEDNESDAY - Mainly cloudy with flurries, 5-15 cm / west to southwest winds, 20-40 km/h, gusting to 60 km/h / freezing level 1300 m / alpine high temperature near -5, low temperature near -8

Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2 have been reported in the region daily since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered).A natural avalanche cycle to size 4 was reported in the neighboring Purcell region on Friday. Also of note, a size 2.5 human triggered avalanche was reported on a northwest aspect at 2250 m in the Purcells on Saturday. This avalanche was triggered remotely from 50-100 m away. A report of this avalanche can be found on the Mountain Information Network. (here)

70-120 cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals) and a sun crust (on south aspects). Strong to extreme winds have promoted widespread slab formation.Another weak layer of surface hoar and sun crust that formed in mid November is up to 120 cm below the surface. This layer is most likely to be a problem in areas where the surface hoar sits on the sun crust. This combination is most likely found on steep, south facing slopes at treeline. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in large avalanches.At the base of the snowpack is a crust that formed near the end of October. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.