Northern San Juan
AvalancheMark Mueller · Dec 28, 2019 · Northern San Juan
Weather
Mostly cloudy skies, periods of light snow with little accumulation, temperatures in the teens, and light winds. Winds veered to the N as I was leaving at 1530 and snowfall increased. 16" snow with 1.1" of water content from this storm.
Snowpack
Although the structure looks to have some potential weakness, recent test results and the solid feel under the skis leave an impression of generally safe conditions. However, at lower elevations a thinner and more fragile structure exists and the majority of recent activity occurred below treeline, some of it digging to the ground.
Avalanche
On the 27th, snowfall far exceeded anticipated amounts and avalanche activity was widespread. Nearly all known highway paths and banks were active and debris covered the inside lane and in several cases crossed the centerline- Larson Creek. Notable avalanches occurred at MM 64.1, 64.3, and 64.4, Valley View, Lake Fork Ranch Bridge, Tommy Carl Bridge, and MM 78.9. Several unnamed locations reached the shoulder. In most cases debris piles were manageable. I estimate that avalanches put some amount of debris on about 700-800' of the highway. On Country Road 30 the Gladiator slide ran nearly its entire length (~200 yds) at several times. Several deposits might have blocked the inside lane, while two deposits that ran later and from higher upslope blocked the entire road, deposits on the white line there were 6 feet deep. Visibility into the high country was limited, but a few D2s were observed. None of which appeared to go to the ground.