Southern San Juan
SnowpackChris Bilbrey · Apr 12, 2022 · Southern San Juan
Weather
Steady snowfall (S1 to S2) during the morning and strong southerly wind. Snowfall decreased around Noon and skies became broken. Blowing and drifting snow observed at all elevations.
Snowpack
We found 4 to 5 inches of new snow below treeline and drifts on leeward slopes up to 8 inches deep. Snow depths increased to 6 to 8 inches above 11,000 feet and drifts up to 12 inches deep at treeline. A common theme we found, constricting terrain features enhanced depth of drifting on slopes below versus broad ridgelines. In general, the new snow was bonding well to the old surface, and fresh slabs remained soft with not much pop. Digging on a northeast aspect at treeline, we found a soft (4F-) layer of moist rounds that appear to be faceting below the new snow. This layer was 8 cm thick and produced sudden planar, propagating failures in tests. These moist, faceted grains are sandwiched between harder snow layers. While we observed these test results, we did not hear audible collapses, but did observe surface cracking on similar slopes approaching 35 degrees. Either the slab/ weak layer combo we found in our snowpit is more isolated in the terrain or stubborn to ski pressure. Continued snowfall, drifting, or surface warming could increase sensitivity in these shallowly buried softer snow layers. Wind-ward slopes at all elevations got blasted by the wind today, and many open areas stripped back to the refrozen old snow surface.