Southern San Juan

Avalanche

Chris Bilbrey · Dec 31, 2022 · Southern San Juan

Weather

Mild, damp day. Off and on snow (S1-S2) with a brief period of limited visibility and the sun poking through around 12:30 pm. The Cloud deck lowered and was obscured for the remainder of the afternoon. Maybe a light sleet or freezing rain event below 9,000 feet leaving a thin crust on the snow surface by 3 pm - all snow above that.

Snowpack

We found 8 to 10 inches of new snow since 12/29. Snowfall over the past two days fell upside-down with wet, dense snow above lighter, softer snow (4F over F). This setup built a shallow but cohesive storm slab on the surface and was reactive in test on north through east to southeast-facing slopes below treeline. All Extended Column Tests (ECTs) evaluating storm snow sensitivity produced propagating failures with less than 10 taps. Deeply buried persistent weak layers remain reactive in tests failing with moderate to hard force depending on the aspect (ECTPs and sudden collapse failures in Compression Tests). A snowpit on a north-facing slope around 11,300 feet had a shallower slab above faceted grains, most likely from being closer to the ridgeline and exposed to more wind scouring. The slab failed with 13 taps and "cash drawered" into the snowpit. This highlights the notion that while the drought layer facets are getting buried deeper in some spots, shallow areas of a slope are where a rider is more likely to trigger a larger slide. Now that slabs are connected across slopes, slides have higher potential to break broader across terrain than you might expect.

Avalanche

None observed today, but visibility into bigger terrain and adjacent slopes was limited by low clouds and fog.