Southern San Juan
AvalancheChris Bilbrey · Apr 4, 2023 · Southern San Juan
Weather
On and off snowfall ranging from S1 to S2 - brief moments of broken skies and decent visibility. Moderate southwest wind along ridges.
Snowpack
We found 3 to 4 inches of new snow around 11,000 feet, and 7 to 8 inches above treeline. Drifting was around a foot deep on leeward slopes and in cross-loaded terrain features. Below the new snow was an obvious layer of dust, but it did not contribute to increased sensitivity where we traveled. Yesterday's strong winds, before the onset of snowfall, stiffened the old snow surface in many places near and above treeline. This firm layer ranged from an inch up to 3 inches thick, was supportive to skis, but breakable to foot travel. Below the wind layer was a softer layer of tiny faceted snow grains. This stiff-over-soft layering likely needs a larger snow load or major warm up to become problematic. A stout crust exist below the new snow on sunny slopes at all elevations. Only sheltered, shady slopes below treeline had a soft, old snow surface below the new snow. In general, we found good bonding between the right-side-up storm snow and varying old snow surfaces. Cracking in the snow was isolated to deeper drifts and below our skis. We triggered a couple of "dinner table" sized wind-drifted slabs directly below the ridgeline on a northerly-facing slope above treeline. Each slide traveled a couple hundred feet down the slope, but did not entrain additional snow volume. Only minor loose snow sluffing around steeper convexities. Digging and probing on west through north-facing slopes near and above treeline yielded fairly uniform upper snowpack layers mostly 1F to P- hardness.
Avalanche
A couple of large natural avalanches that likely ran during the 3/22-23 cycle. These slides occurred in areas difficult to see from the highway.