Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

Impressive avalanche activity occurred on McGee Mtn during our last storm. There are many crown lines and debris fans visible on McGee with several different characters evident.  I was only able to observe from the road and we have not had the opportunity to conduct more thorough investigations, but I suspect several avalanche events occurred at different times during the storm and under different conditions. 

The most unique and eye-catching avalanche occurred in the East gully just above the McGee Creek rd. and Crowley Lake Drive intersection. Like a few others in the area this avalanche has some impressive wet debris.  Reminding me of an old play doe machine I had as a kid, this debris didn’t so much fan out as it snakes through low-angle terrain for quite a while towards Crowley Lake Drive. 

I suspect this avalanche, and several others with similar character likely started as dry wind slabs high on the slope and entrained wet snow as it traveled down the slope and crossed a threshold. (rain/snow line or cold to warm temperatures.)

Mid-day on the 9th we saw quite a warm-up which led to rain on snow at lower elevations and heavy wet snow even at higher elevations. We suspect that the rain-snow line was likely mid-slope on McGee during the 9th.  Avalanches occurring during this time frame could have easily started as dry avalanches at higher elevations becoming increasingly wet as they entrained more and more snow. Quite an interesting setup and one not uncommon in areas with large relief and fluctuating snow levels.