Recent snow with variable wind makes human triggered avalanches possible. Areas of the most concern are in exposed terrain at the middle and upper elevations where wind has transported snow creating firm cohesive slabs. Visually identify and feel for firm wind drifted snow above soft snow before committing to consequential avalanche terrain.
Wind slabs have developed above 8500' over the last several days with light to moderate winds that have shifted direction from westerly to northerly. Snow from the last storm cycle is still available for transport, especially in the upper elevations across all aspects. Slab depths will likely be 1 to 2 feet but could be as deep as 3 feet in isolated areas.
Powder fever, that euphoric feeling we all know riding fresh snow. November and December have provided us with ample opportunity to pursue this feeling. For many of us, winter has already felt long. But with January upon us, it’s important to take a step back and understand that the snow is still transitioning from an early to mid season snowpack.
For the Tetons, the snowpack has already transitioned it seems. Today the persistent slab was removed from the avalanche problems. These old layers have become unreactive and are now considered dormant. Our forecast team had a long hard discussion. The last reported persistent slab avalanche was Rendezvous Peak on Dec 16. Since then, the zone has received 59 inches at 10,450’ (Summit WS), 46 inches at 8,800’ (Chief Joseph WS) and 47 inches at 8,200’ (Mid Mtn WS). With all this snow, the persistent weak layers have become more and more stubborn over time. This last storm was a good test, adding a heavy load and no reported natural or human triggered avalanches on persistent weak layers. With that being said, avalanche paths that previously slid in the middle of December (such as Game Creek), could become an issue later down the road as slabs build back over the weak layers.
Wind slabs are now the main concern, as wind direction shifted from west to north yesterday with intervals of moderate intensity. These slabs could be found across all aspects above 8500', loading areas that typically are not. The amount of snow available for transport will decrease as the recent snow continues to settle.
