The avalanche hazard will steadily increase throughout the day today, especially at the upper elevations. New snow and wind will combine to form sensitive slabs that are 1-3 feet deep. There is still a possibility that wind slabs in motion may step down to deeper layers resulting in large avalanches in very steep, rocky terrain. Conservative decision making and cautious route finding are advised.
Wind slab hazard will steadily increase throughout the day today. With 4-6 inches of snow forecasted and SW winds gusting into the 30s these slabs could be 1-3 feet deep and sensitive to human triggers. Temperatures and winds are forecasted to peak sometime around early afternoon.
There is plenty of snow available for transport from the previous storm cycle.
There are currently 2 major persistent weak layers buried within the top 3-6 feet of the snowpack. These layers are failing in the moderate-hard range in stability tests and have not been showing a propensity to propagate lately. New snow and wind will stress these buried weak layers.
Another storm system is on tap for today as a pretty good plume on moisture streams in from the Pacific on a westerly flow. 4-6 inches of snow is expected by 5 pm today with SW winds in the 10-20 mph range (gusting into the 30s). There seems to be plenty of snow available for tranport that was left over from convective snow showers yesterday morning.
Upper elevations in the Tetons have received around 1.5-2 inches of water in the last 72 hours. That water came from a recent atmospheric river event that affected the range on December 28/29. The storm came in wet and heavy, with high winds and some rain up to 7500'. Orographic convection kicked in later on the 29th and continued into the morning hours of the 30th, resulting in several more inches of low density snow (especially on the west side of the range).
Observations have been limited from the last few days but no human triggered avalanches have been reported. It is likely that some natural wind slab activity took place some time around the evening of the 28th (associated with frontal passage). There were also some reports of stability tests failing on a layer of graupel that fell mid-storm on the afternoon of the 28th. Snowfall and light winds since have conspired to cover up any avalanche activity (if it did occur).
The November 27th layer has been dormant since about December 16. A thin layer of near surface facets that was buried around December 5 seems to be gaining strength as well.
