Northern San Juan
AvalancheKrista Beyer · Mar 16, 2024 · Northern San Juan
Weather
What a week for weather prediction. Clouds, fog, S5 snow flurries for 15 minutes, blue skies, dry roads in Silverton, and deeper than expected snow at upper elevations. Sounds like it's March. Moderate southeast winds reported on nearby weather stations, but calm on northwest aspect. Cloud cover and sunny skies dipped in and out throughout the morning. Temperatures reported above freezing for a short time mid-day at 11,000 feet.
Snowpack
About 12 inches of storm snow observed near treeline. This snow likely consolidated 4-6 inches over the past 24 hrs, but very little slab was obseved. New snow fell on a 4cm pencil hard crust. On the 15th, new snow was reactive to ski pressure, but any loose dry sluffs did not move far down the slope. On the 16th new snow was unreactive to ski pressure. No visible dust layer was found in the pit, but dust could be seen locally on this aspect. Moderate ECT and CT failures were observed at a density change in the new snow and below the crust. None of these layers propagated on ECT tests. Height of snow ranged from 100-140cm near treeline on northwest aspect. Below treeline snow height was in the 60 to 100 cm range and close proximity to basal facets made for a punchy skin track experience. While the CR 2 snowpack remains shallower and weaker than other areas in the silverton area, observed persistent weak layer activity remains limited and isolated.
Avalanche
Widespread small loose activity on many aspects near and above treeline. Loose activity was observed in action during sun breaks in between the clouds. Loose activity looks like it occured on both the 15th and the 16th. Some loose activity was long running and picked up mass on the way down. Two slab avalanches were observed, both small. One was isolated to the new storm snow, the other broke on persistent weak layer and while it didn't propagate wide, it dislodged some large chuncks of hard slab. Both were on north aspects.