Southern San Juan

Avalanche

Chris Bilbrey · Mar 29, 2024 · Southern San Juan

Weather

Mixed skies ranging from overcast to broken to obscured. Very light snow showers lasting no longer than 15 to 20 minutes. Temperatures did not feel abnormally cold, but general consensus was damp and cool.

Snowpack

The most prominent, widespread persistent weak layers are thin, generally 4F, and did not have significant hardness differences in the snowpits we dug. However, they are shallow enough that digging down to investigate is fast and easy. Probing across aspects, the most obvious differences in upper snowpack layers was on northerly-facing slopes. Sunny slopes are a sandwich of crust and melt-form clusters. Below treeline these crust are more breakable, and grains in-between are weaker and more suspect to failure during a big warm-up then higher in elevation. Digging on a north aspect near treeline, we found an upright and somewhat preserved layer of Surface Hoar. This is the first snowpit this season I've found these problematic feathers buried below a slab. The slab above was soft and ECTs only produced non-propagating failures. With a hard shovel pry, the block easily sheared off - similar to a resistant planar failure in a Compression Test. Drifting is the main driver of elevated hazard at upper elevations, and crust continue their broader evolution on slopes now that it's almost April. Below treeline, the snowpack is mostly status quo till it sees another meaningful snow load or period of non-freezing temperatures.

Avalanche

We're able to initiate a couple of shallow, fast-moving sluffs on steep, north aspects near treeline. Sluffing confined to the top 8 to 10 inches of recent snowfall, and size of terrain limited potential size of slides.