Northern San Juan

Snowpack

Ann Mellick Bill Nalli · Mar 3, 2020 · Northern San Juan

Weather

Sunny with a brisk NNE wind above treeline. Mild temps in the sunny valleys, but cool in the shade and on exposed ridgelines.

Snowpack

The snowpack varies greatly depending on aspect and elevation. Sunny slopes have surface crusts which grow thicker by the day, especially at lower elevations. The snowpack on all northerly slopes remains wintry and cold. We found a concerning snow structure on a northeast aspect near treeline today at 12,000' with a very firm surface slab failing on well-developed mid pack facets. This structure is isolated to exposed and wind affected areas near and above treeline, but we have not found it to be widespread. Pit is an example of an emerging and evolving persistent weak layer. Some northeast aspects at all elevations are shallow. Where HS is around 120cm the lower half is 2mm facets mid pack and 3mm depth hoar. This location has a small slab that is made up of multiple snow and wind events, now settled into the top 40cm. ECTP 21 @ 45 and CT 11 SC at 45 suggest that where this structure exists, stability is poor to fair. So far this is still isolated as many of these shallow areas just don't have much of a slab on top. If you find one now, you could pop out a little pocket but more concerning will be once we get the next couple storms adding more load and slab.