Avalanche Forecast
Regions: North Columbia.
Considerable alpine danger is based on storm snow totaling 20+ cm by Saturday afternoon which is expected to do two things:
1. Create a touchy storm slab problem.
2. Potentially wake up the persistent slab problem.
Prepare for rapidly changing conditions and increasing hazard.
Confidence
Low - Forecast snowfall amounts are uncertain. Uncertainty is due to the limited number of field observations.
Weather Forecast
It’s late November and the weather pattern is bringing winter to the door this weekend. The region should get a nice re-fresh from the system.
FRIDAY NIGHT: 5 to 15 cm of snow possible with greater accumulations in the north of the region, freezing level holding around 1200 m, light to moderate southwest wind.
SATURDAY: Storm day, visibility is likely to be poor, freezing level around 1200 m, moderate west/southwest wind, 5 to 15 cm of snow possible, with another 10 to 20 cm possible Saturday night.
SUNDAY: Broken cloud cover, freezing level around 1300 m, moderate west wind, 1 to 5 cm of snow possible.
MONDAY: Broken cloud cover, freezing level near valley bottom, light northwest breeze, no significant snowfall expected.
Avalanche Summary
Very little recent avalanche activity has been reported, but times are changing this weekend. It's worth checking out this MIN report from a skier triggered avalanche in the neighboring Glacier Park Region on Monday. As storm snow totals begin to approach 20+ cm natural avalanche activity is likely.
Snowpack Summary
Avalanche Problems
Storm Slabs
Storm totals could easily exceed 20 cm Saturday afternoon and this system has a fair amount of wind associated with it too. Conditions will likely change rapidly over the next 24 hours and storm snow is not expected to bond well to the old surface, avalanches in motion could step down to more deeply buried weak layers too. Frankly, we don't know much about this snowpack right now, and we don't trust it. Keep it conservative on Saturday people.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
A problematic interface of surface hoar on top of a melt freeze crust can be found 40 to 100 cm below the surface. This "October Crust" is showing sudden & repeatable results when subjected to snowpack tests. This weekend's storm cycle will be a great test for this interface and should reveal a lot. That being said, we don't trust it and conservative terrain choices are the best defense this weekend.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 2.5