Avalanche Forecast

It’s mostly dribs and drabs of snow for the next few days with increased wind in the higher alpine terrain features. A bigger storm is on the horizon as we enter the New Year.

THURSDAY NIGHT: Freezing level at valley bottom, moderate to strong south/southwest wind, potential for 4 to 12 cm by Friday morning.

FRIDAY: Overcast, freezing level near valley bottom, moderate to strong west/northwest wind, 2 to 8 cm of snow possible during the day.

SATURDAY: Broken cloud cover, freezing level at valley bottom, light variable wind at most elevations, moderate to strong west/northwest wind in high elevation alpine terrain, trace of snow possible.

SUNDAY: Scattered cloud cover, freezing level at valley bottom, light variable wind, no significant precipitation expected.

On Wednesday a size 1.5 wind slab avalanche failed naturally on a steep east facing feature near treeline. Loose dry avalanches to size 1.5 ran naturally and were intentionally triggered by riders in steeper alpine terrain too. The more notable avalanche from Wednesday was a natural size 3 persistent slab that failed on a south facing feature at 2500 m. This was likely solar induced, this observation shows us that although triggering of the deeper December 11th surface hoar layer is unlikely, it is still possible. Natural avalanches size 2.5 to 3 were also observed in the neighboring Glacier National Park in steep terrain, these avalanches were running to the top or middle of runnouts.

Avalanche activity is tapering, but avalanches during and just after the storm were spectacularly large and destructive. Last weekend there were numerous reports of natural, human and explosive triggered avalanches up to size 3.5. Many of these were triggered remotely.

The South Columbias received upwards of 60 to 100 cm from last weekend's big storm which is slowly settling into a slab. There is now a great deal of uncertainty as to how quickly the snowpack is regaining strength. Anywhere from 100 to 160 cm of snow is now resting on a widespread layer of large, feathery, surface hoar which we're calling the "December 11th Surface Hoar." Activity on this interface has really tapered off, but this layer produced some very large natural avalanches during and just after the storm. 

A combination of surface hoar, crust & facets formed in late November is now over 170 cm deep. This layer is likely trending toward dormancy.

• Start on smaller terrain features and gather information before committing to bigger terrain.
• Avoid convexities, steep unsupported terrain and rocky outcroppings.
• Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
• Avalanche hazard may have improved, but be mindful that deep instabilities are still present.