North Columbia

Natural avalanche activity is expected to persist through the day Friday and the current setup is primed for large human triggered avalanches. Stay conservative as the snowpack adjusts to the recent rapid loading.

Moderate - Intensity of incoming weather systems is uncertain on Friday

The storm should continue to produce significant snowfall Thursday night and Friday. The weekend offers a bit of a break in the action with the next significant storm expected Tuesday evening.THURSDAY NIGHT: Freezing level around 500 m, moderate southwest wind at most elevations with strong to extreme southwest wind at ridgetop, 10 to 25 cm of new snow.FRIDAY: Overcast, freezing level beginning at valley bottom rising to 800 m throughout the day, moderate southwest wind at most elevations with strong to extreme west/southwest wind at ridgetop, 5 to 20 cm of new snow.SATURDAY: Scattered cloud cover at dawn building to broken cloud cover by sundown, freezing level beginning at valley bottom rising to about 600 m throughout the day, light southerly wind with moderate southwest gusts at ridgetop, no significant precipitation expected.SUNDAY: Overcast, freezing level around 500 m, light southerly wind with moderate southwest gusts at ridgetop, 1 to 5 cm of snow expected.

Preliminary reports from Thursday were just starting to come in at the time of publishing this bulletin: Natural storm slab avalanches size 1.5 to 2.5 were reported on all aspects between 1200 and 2500 m with crowns up to 60 cm in depth.  Natural avalanche activity is expected to persist through the day Friday.On Wednesday avalanche activity was limited to natural and human triggered wind slab avalanches to size 2 on all aspects. A notable MIN report from Saturday December 29th describes a large (size 2) snowmobile remote (from a distance) triggered storm slab in the Clemina Creek area link here. On December 31st a notable avalanche occurred in the neighboring Glacier National Park region. The large (size 3) persistent slab release was skier triggered below ridgecrest on a southwest aspect in the Connaught Creek area. Photo available here.

As of Thursday afternoon the storm has produced up to 45 cm of new snow accompanied by moderate to strong wind out of the south. Wind fueled storm slabs up to 120 cm in depth were reported in lee features Thursday. This adds to the 30 to 40 cm of snow that fell last weekend. There are a few reports of spotty surface hoar underneath all of this new snow, but for the most part the storm snow does not sit on any kind of persistent weak layer and is expected to rapidly settle this weekend as the storm exits to the east. An aspect-dependant mix of facets, surface hoar, and sun crust buried mid-December now 100 to 150 cm deep, is reported to be less reactive in snowpack tests and shows 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.