Recent storm snow sits primarily on faceted snow, surface hoar, and, in some areas, sun-crusts. Slab avalanches involving these weak layers can be human triggered today on a variety of aspects and at all elevations. These avalanches have the chance to be significantly larger in terrain above 9000 feet. As they become less sensitive to triggering, they also become harder to predict and conservative decision making remains essential. Snowpack evaluation can help to determine unstable areas. Remember that just this weekend many remotely triggered avalanches were reported and at least 7 people were caught in slides. Yesterday, one slide was reported. It occurred at 8700 feet on a southeast aspect and was remotely triggered by a snowmobile.
In steep avalanche terrain above 9000 feet, skiers and riders have the potential to trigger persistent slabs ranging in depth from 2 to 4 feet. Below that elevation, slabs of 1 to 3 feet are possible.
Snow is to develop by midnight, continue during the day and diminish to snow showers by evening. In the Tetons, accumulations of 3-6 inches are expected by sunrise with another 2-4 to fall during the day. The Togwotee and Southwest Trails areas will see slightly less accumulations. Temperatures at high elevations are to fall to the teens overnight with highs tomorrow in the low twenties. Winds are to increase to averages between 20 and 30 mph as the snowfall begins. They will also veer from the southwest to northwest as the system passes and colder air moves in Wednesday night. In the Tetons, the general avalanche danger will remain Considerable above 9000 feet and Moderate below that elevation. If predicted snowfall and winds validate, then new wind slabs will start small and grow in size and sensitivity as the day progresses in terrain above 8000. This load will also increase the chances the chances for humans to trigger persistent slabs involving the recently active layers buried in late January. In the Togwotee and Southwest Trails areas, conditions differ in that the snowpack is weaker overall and contains more faceted layers. Less action has occurred in these areas due to less snow being received in recent storms however that could change rapidly if a significant storm were to impact them. Tomorrow, less snow is expected in these areas and although small wind slabs will likely develop and slides involving deeper layers remain susceptible to human triggers the rating will remain as Moderate above 7500 feet and low below that elevation where avalanches are unlikely except for in isolated pockets.
