Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Friday

The storm should continue to produce significant snowfall Thursday night with lingering convective flurries persisting through the day 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 600 m, moderate southerly wind at most elevations with strong to extreme southwest wind at ridgetop, 10 to 30 cm of new snow.FRIDAY: Overcast, freezing level beginning around 500 m rising to 1000 m throughout the day, moderate southwest wind at most elevations with strong to extreme southwest wind at ridgetop, 5 to 10 cm of new snow.SATURDAY: Broken cloud cover at dawn dissipating to just a few clouds by sundown, freezing level beginning at valley bottom rising to about 1000 m throughout the day, light south/southwest wind with moderate southwest gusts at ridgetop, no significant precipitation expected.SUNDAY: Overcast, freezing level beginning around 500 m rising to about 800 m throughout the day, light southerly wind with moderate southwest gusts at ridgetop, no significant precipitation expected.

Preliminary reports from Thursday were just starting to come in at the time of publishing this bulletin: Storm slabs up to size 2.5 were triggered by explosive control work on all aspects between 2000 and 2400 m. A skier accidentally triggered a size 1 storm slab on a steep north facing feature at 2250 m as well. Natural avalanche activity is expected to persist through Thursday night and may continue into Friday morning.On Wednesday avalanche activity was limited to dry loose avalanches in steep terrain. The exception was a report from the RMR backcountry where a group triggered a size 2.5 avalanche on a steep south/southeast facing terrain feature immediately lee of ridgecrest at approximately 2250 m. A ski was lost, but everyone made it out okay.On December 31st a notable avalanche occurred just north of the region. The large (size 3) persistent slab release was skier triggered below ridgecrest on a southwest aspect in the Connaught Creek area in Glacier National Park. Photo available here.

As of Thursday afternoon the storm has produced 15 to 30 cm of new snow accompanied by moderate to strong wind out of the south. Storm slabs up to 80 cm in depth were reported Wednesday evening in lee features. 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 80 to 140 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.