Central Sierra Nevada
Peligro de aludes
Lo esencial
The shallow snow on cold shady slopes keeps getting weaker. Avalanche problems with this weakness should remain unlikely until new snow or rain adds weight to the snow. Those moving on snow will find a mix of surfaces including firm icy areas.
Avalanche Discussion
The warm dry weather has melted almost all of the snow off of the sunny southerly aspects and lower elevation areas. Short days, long nights, and low sun angles have allowed the upper elevation northerly aspects to stay shaded and cool. A shallow but mostly supportable snowpack does still exist on NW-N-NE aspects above 8000 to 8500 ft. The supportability comes with a catch though since a mix of firm icy crusts and breakable crusts exist on the snow surface.
The same cold shady conditions that allowed the snow to remain on the northerly aspects have also caused weak layers to form in the snowpack. The dense snow and solid rain crusts that accumulated in October and early November have deteriorated to a mix of weak sugary snow (facets) and eroding crusts in the mid and upper parts of the snowpack. Below these weakening layers, ice exists at the bottom of the snowpack in many areas. The long nights, short days, and low sun angles will allow the facetting process to continue building weak layers in the snowpack.
For now, avalanche activity remains unlikely because little to no slab exists on top of the weak layers. However, the weak layers that have formed during this dry spell could lead to complicated avalanche problems when new snow or rain returns to the region. Mapping out the areas where these weak layers exist and monitoring them as they form will provide a key piece of information for decision-making after new snow buries them.
Recent Observations:
* 1 to 3 feet of snow exists on NW-N-NE aspects above about 8,000 ft. The snow surface remains highly variable with a mix of firm icy crusts and breakable crusts in most places.
* Almost all SE-S-SW-W aspects are snow-free with continuous bare ground exposed. A few high elevation E-SE aspects hold some snow cover.