Tetons

Snow is expected to fall for the remainder of the week. The National Weather service has issued a Winter Weather Advisory for the area from 2pm this afternoon until 8pm Thursday. New snow is falling on a snowpack that has buried weak layers and is topped with newly formed surface hoar, near surface facets and in some south facing terrain, sun-crusts. Above 7500 feet the hazard is currently limited to isolated areas where skiers and riders have the potential to trigger slab avalanches one to three feet deep. The difficulty is in identifying where these lingering instabilities lie, although terrain in and around cliff areas remains the most suspect. As new snow accumulates and temperatures rise, new shallow soft slabs will start to develop. Although not enough accumulation is expected today for a significant surface slab problem, monitor wind loaded starting zones this afternoon if accumulation rates increase. The snowpack below 7500 feet has poor structure but avalanche activity is not expected at the lower elevations today as slopes are just starting to be loaded.

Pacific moisture in a southwest flow is expected to impact the forecast area tonight through tomorrow. Snowfall amounts will favor the Tetons, where the National Weather Service has issued a Winter Weather Advisory through 8 PM on Thursday, with 6-12 inches by tomorrow afternoon. The Greys River area is expected to receive 3 to 6 inches and Togwotte Pass will only see a few inches. Southwesterly winds will be fifteen to twenty miles per hour with higher ridgetop gusts, and mountain temperatures will rise into the mid to upper twenties. Tomorrow morning the avalanche hazard is expected to start out at Moderate in all the forecast areas. It will be possible for riders and skiers to trigger slab avalanches one to four feet deep in avalanche terrain. As the day progresses, the hazard will increase in the Teton and the Grey’s River areas, where more significant snowfall is expected. The new snow along with moderate southwesterly winds will form wind slabs along ridges and wind loaded terrain features. Increased loading throughout the day will cause these slabs to become more sensitive to triggers, and the additional weight on the snowpack may cause buried weak layers to become reactive. It will be important for backcountry travelers to monitor the intensity of the storm and plan accordingly.