Weather
Just like a Fourth of July flyover, strong southwesterly winds roared into the western valleys of the San Juans early this morning. The 50-70mph gusts profoundly changed the character of the snow surface above treeline: scouring some slopes back to bare ground, creating very hard unbreakable crusts, and sublimating a lot of snow back into the atmosphere. The wind also penetrated into the trees, creating a thin punchy wind crust in some open meadows near treeline.
Snowpack
The snow surface conditions currently fit neatly into three boxes: melt-freeze crusts on sunny slopes, faceted snow on shady wind-sheltered slopes, and firm wind-effected snow almost everywhere above treeline. We dug two snow pits at 11,400', just below treeline, on a sunny southwest-facing slopes and a shady north-west facing slope. In the shade, the snowpack is faceted from top to bottom, with no slab present. Compression tests yielded hard failures in larger faceted grains close to the ground. An extended column test yielded no results. On the sunny slope, a thin melt-crust sits on the surface, and different-sized facet grains below. Long and short column tests highlight a slab over a weak-layer combination with failures around 20 cm from the surface. Hand-hardness highlights this interface. However, this is likely not an issue now, and many southerly slopes at upper elevations are getting stripped by the wind. Sunny slopes that do hold snow could come into play in terms of areas where we could trigger avalanches earlier this year than in the past.