Northern San Juan

Avalanche

Mike Barney · Apr 1, 2021 · Northern San Juan

Weather

Light southwest winds with clear skies and 40F at 12,000 feet around 2pm.

Snowpack

Above treeline brown tinted snow is showing in most places on southerly aspects making me think that the last storm's snow has melted away and the potential for loose wet avalanches has passed on these slopes. Northerlies remain white, cold and surfaces are a mix of old, thin, smooth wind slabs and soft faceted textured snow. West aspects had a 3 to 4 cm melt freeze crust that was frozen and just starting to melt on the surface at 2pm. Cold snow was below the crust to the ground and the mid-pack was 55cm of 1f to pencil hard snow with 35 cm of basal facets. Free water has not moved through this upper elevation west aspect. With 15 cm of cold snow under the thin melt freeze crust a LWa cycle will be possible as this fist hard snow will become saturated quickly tomorrow. This pit was on a 24 degree slope, and I think that steeper westerlies above treeline will have a thinner midpack and be more susceptible to wet slab avalanches in the next few days than this pit suggests. The thick (10hr+) freeze overnight kept slopes supportable to skis and a snowbike in the open flats BTL until about 2 or 3pm above 10,000'. I would suspect that this will not be the case tomorrow afternoon. Rivers are coming up and the melt is on.

Avalanche

One large cornice fall that triggered a small avalanche below and ran in steep terrain 1000'. This was on a north aspect above treeline and we estimated it failed in the last two days.