Southeast Mountains

On the north side of the compass, observers reported human-triggered soft slabs up foot thick: the new snow breaking on weak facets.  Conditions become more dangerous as you gain elevation into windloaded terrain, where slabs will be thicker and can break wider, deeper, or be remotely triggered.   Options to reduce your risk exist on lower-angle slopes, smaller terrain features, or lower elevations and more southerly aspects.  

The weak snow that formed during our prolonged dry spell was not happy about the 8" to 14" of new snow.  The most dangerous conditions exist at higher elevations in snow-favored areas north and west of town, where drifting snow formed fresh slabs up to two feet thick that broke wider and showed remote triggering potential  (See this video from Schuylkill Ridge or this video from the Marble side).  In wind-sheltered terrain at lower elevations, slab instabilities are smaller and less common, and should quiet down sooner, especially below 10,000'.  These examples from Pittsburg and Snodgrass illustrate what you should manage for on northerly aspects below treeline.   Despite limited visibility so far, our avalanche rose from the storm shows the bullseye is on northeast aspects: the result of windloading from southwest winds onto weak, faceted snow.  Note the handful of storm instabilities off of high southerly aspects as well.   While slabs have demonstrated better bonding to the crusts at mid and lower elevations (ex. Irwin), we have more uncertainty and concern for poor bonding in the alpine due to a thin layer of faceted snow that was developing just before the storm arrived (see this pre-storm observation from the Ruby Range).  These storm instabilities will migrate into our next generation of persistent slabs in the near future, and the February 11th storm interface will remain problematic for a while.  Let us know where you are seeing signs of instability or recent avalanches to help us dial in where this layer is most problematic as we head into a bigger loading event next week.  

There are several other weak layers deeper in the snowpack that formed during dryspells in November, December, and January (So, like, the whole winter...), and a pockety distribution of old, harder slabs above them at higher elevations.  This most recent storm wasn't a huge loading event: SWE increases ranged from 0.6" at Butte to 1.4" at Schofield Pass.  Step-down potential is expected to be fairly isolated and stubborn for now, but some of these early-season weak layers may become more active if we continue to see productive snowfall through the rest of the month.  Forecasting and managing for deeper weak layers always carries more uncertainty.  Thankfully, most of our southerly facing terrain saw enough meltwater last week to eliminate or significantly reduce deeper concerns.