4 days have now passed since the last significant snowfall. The last storm dropped 20-30” of new snow between 3/13-16 for most of the forecast region, except for the southern reaches outside of Bishop where the mountains received closer to a foot. Snow sensors are showing that this new snow has now settled to about 2/3 of that total amount. While evidence of widespread natural avalanche activity occurring during the last storm has been reported, no signs of current instablities have been reported over the last several days except for some very minor small loose wet point releases. Tests on the mid-storm graupel layers that were found around the June area have been shown to be stabilizing.
With today’s cloudy skies and light snowfall expected to begin this afternoon, instabilities of all sorts should remain low through today unless new snowfall amounts far exceed expectations. At elevations below 9000', some slope warming will likely occur on all aspects due to warm temperatures and cloud cover and light drizzle. Precipitation amounts are expected to be quite light today, so rain on snow instability concerns should not develop. In addition to wind slabs, storm slabs could become a very isolated concern late tonight for sheltered steep slopes that receive more than a half a foot of new snow, but the low snowfall intensity will keep this concern fairly minimal. Unless you are going to be out exploring the mountains late tonight by headlamp, this should not be a concern at all.
Wednesday night the story will begin changing dramatically as heavy snow fall rates begin and continue through Thursday night as a significant Atmospheric River brings heavy moisture to our area. Avalanche danger will almost without a doubt rise to HIGH, and possibly beyond. This intense loading, the highest we’ve seen yet this season, could very well re-activate the deeper weak sugary facet layers in the snowpack, and VERY large avalanches could become a real possibility.