Southern San Juan

Snowpack

Bill Nalli · Dec 2, 2019 · Southern San Juan

Weather

Mild temps and calm winds. High clouds but not enough to trap heat and produce greenhousing.

Snowpack

Snow depths range from 90 to 60 cm on the North through East aspects below treeline. Good coverage at these elevations on the shady aspects but slopes that face Southeast, South and Southwest are still thin and melting closer to the ground with each warm sunny day. My goal today was to hunt out old October snow that has turned to depth hoar and is currently our most significant weak layer. We know it exists near and above treeline but the zone below treeline has had few observations and visits due to low coverage. Most terrain below treeline had little to no snow prior to mid November and is comprised of strong snow from the last couple storms. BUT, some of it does. Today at 11,000' on a north aspect I found 13cm of depth hoar near the ground below a 75 cm slab of soft settled snow. Where this structure exists on a steep slope below treeline it is still likely for human triggered avalanches. As you descend in elevation, these areas are more scarce and at around 10,000' in the South San Juan's this hazard begins to go away and most slopes are stable.