Snow showers forecasted for yesterday afternoon and overnight were underwhelming. An inch or two of snow fell in the northern half of the forecast area, with up to 3 inches in the mountains outside of Bishop. But these kinds of minor precipitation events are typical for spring. Mostly sunny skies, warm temperatures, and light winds today may allow the surface snow to warm through. Small wet avalanches will become increasingly possible throughout the day. Watch for rollerballs coming down the slope around you, especially in steep rocky terrain where the sun is most intense. Small point releases are an indication that larger avalanches are possible. Timing your day to be off of suspect slopes before before they thaw too deeply is the easiest way to avoid the problem.
All season we have been discussing and tracking layers of persistent, weak, sugary snow (facets) that developed in areas that had shallow snow coverage prior to the storm that began March 1st. That event finally dropped enough snow to act as a cohesive slab overlying the persistent weak layers and some very large and destructive avalanches occurred through March 4th. While the threat of failure in the buried facets seems to be improving, deeply buried weaknesses are notoriously hard to predict. The last reported collapse of the buried weak layers was on the 6th, but snowpack tests as recently at yesterday have continued to indicate that failure in these sugary snow grains is not impossible. With few observations, we don’t entirely know what to expect from these layers, especially outside of Mammoth. So doing your own stability assessment is the best way to see what these layers are doing in your area. Warm temperatures will most likely allow the snow to gain strength, but slowly. We will have to monitor as temperatures dip below normal again later this week. More precipitation Tuesday through the weekend may create additional stress on the weak snowpack.
