North Columbia

A vigourous storm system is forecast to bring heavy amounts of snow and moderate to strong winds to the region Wednesday night through Thursday.

Moderate - Intensity of incoming weather systems is uncertain on Thursday

WEDNESDAY NIGHT: Snow, accumulation 15-25 cm / Moderate southwest wind / Alpine temperature -7 C THURSDAY: Snow, accumulation 20-30 cm / Moderate to strong southwest wind / Alpine temperature -3 C / Freezing level 1200 mFRIDAY: Snow, accumulation 10-15 cm / Moderate to strong south wind / Alpine temperature -7 C SATURDAY: Scattered flurries / Light to moderate west wind / Alpine temperature -6

Expect to see widespread avalanche activity on Thursday as a vigorous storm passes through the region Wednesday night through Thursday.A notable MIN report from Saturday describes a large (size 2) snowmobile remote (from a distance) triggered storm slab in the Clemina Creek area. (link here) Another recent notable event was a large (size 2.5) persistent slab release that was skier triggered below a ridgecrest on a southwest aspect in the Connaught Creek area in Glacier National Park.

20-30 cm of new snow falling Wednesday through the day and night will add to the 30-40 cm of snow that fell last weekend. Moderate to strong southwest winds along with a rise in freezing level associated with the latest weather system is expected to promote storm slab development at all elevations.An aspect-dependant mix of facets, surface hoar, and sun crust buried mid-December now 100-150 cm deep, is reported to be less reactive in snowpack tests and showing signs of strengthening. A heavy trigger might still coax reactivity out of steep north and east facing slopes between 1900-2300 m or a steep south-facing slope in the alpine.The lower snowpack is generally strong and settled, with a crust that formed in late October near the bottom of the snowpack.