Togwotee Pass

The combination of new snow, wind, and buried weak layers will make human triggered avalanches possible today. The avalanche hazard will increase throughout the day today as new snow accumulates and SW winds increase. Cracking within wind drifted snow and collapsing of the snowpack are warning signs of heightened avalanche conditions. 

A shortwave trough will impact the forecast area today through early tonight. Snowfall amounts in the 2-4 inch range with WSW winds in the 15-20 mph range are forecasted. This trough precedes a much larger closed low system that is currently off the coast of British Columbia. New snow and wind will combine today to form fresh wind slabs with new/pre-existing snow. This new snow will also stress buried weak layers, though to what degree remains uncertain. 

In a general sense there are plenty of weak layers to be found in the Togwotee Pass zone but uniform slabs are harder to come by. 

So far Triple Dip La Nina conditions are treating the Tetons favorably. Current snow water equivalent measurements show Grand Targhee to be 114% of median value while Phillips Bench sits at 130% of median. The Togwotee Pass snotel is at 95% of median and Willow Creek in the Salt River Range is 135% of median. 

Nearly every snowpit in the observations over the past several weeks has continued to propagate at the middle and upper elevation bands (around 7,500 to 10,000 feet). These areas include well traveled areas like Glory Bowl and the sidecountry terrain of Jackson Hole Mountain Resort. The results of avalanche mitigation on closed runs at Snow King on Tuesday, continued collapsing in the snowpack and a remotely triggered avalanche should serve as bullseye information.  These recent events are a good reminder that this  snowpack is extremely variable across the terrain with a level of complexity that makes assessment challenging. There is no doubt that luck has been playing a more important role than it should in the lack of human involvment in avalanches in recent days. 

The weak layers in the snowpack are persisting predominantly in the middle to lower elevations, dependent on the mountain range.  These pits are failing on a variety of weak layers found on both southerly and northerly aspects, and primarily hold a mix of thicker layers of small facets, and/or surface hoar.  A common theme appears to be high strength in extended column tests (high # of taps before failure) and fair structure (not the worst, not the best).  The slab above these weak layers can be significant and thick in some places which may make them harder to trigger, but it is possible to find thinner spots in our developing snowpack where you can trigger this layer. Low probability but high consequence scenarios like these are difficult to plan for and navigate around, leaving the aforementioned luck playing an outsized role in safe travel in the terrain.