Northern San Juan
AvalancheAmy Pertuz · Mar 25, 2021 · Northern San Juan
Weather
Increasing clouds in the morning gave way to snow all day, with intermittent periods of squally, convective showers producing higher snowfall rates alternating with periods of light snowfall. SW winds increased during the day and were rude on ridgetops by mid day, and moving snow into fresh windslabs on Northerly and Easterly aspects.
Snowpack
HST from the last 2 days is 8” at 10,500’ and 14” at 11,400’, but sustained SW winds created windslabs 2ft thick on lee slopes at upper elevations. HS on a NE aspect near tree line was 236cm.. The trickiest drifting was near tree line, where the snow was clearly drifted but not as stiff or slabby. On more exposed slopes, we experienced shooting cracks to 10ft in the windslab. This was occurring on small near surface facets buried earlier this week, about 2ft deep. The new snow was bonding well in areas travelled. With a new assortment of windslabs, crusts, and near surface facet layers, the upper snowpack has become a lot more complicated in the last few weeks, with many new persistent weak layers lurking in the upper pack. On an East aspect near tree line, a small facet layer 110cm deep produced sudden failures in CT but did not propagate in large column tests.
Avalanche
Poor visibility, but no avalanches. We did experience shooting cracks.