The Wyoming Department of Transportation is planning to close Teton Pass at 9 AM due to the threat of wet slides. They will reassess conditions at 3 PM. The avalanche hazard will be a function of the temperature, the elevation of the rain line and the amount of precipitation received. If copious, sustained rainfall occurs into the higher elevations, the general avalanche hazard might increase to High in the afternoon. Wet slides, which could release naturally, will be the primary concern. These avalanches have the potential to travel long distances and entrain large amounts of snow. In the upper elevations, the chance for backcountry travelers to trigger small to large wind slabs will be on the increase as the day warms. Most terrain below 7,500 feet is either bare or has undergone multiple melt-freeze cycles. However, with the second night of above freezing temperatures and rain on the way, steep terrain with a deep, isothermal snowpack should be avoided.
Significant wet slabs and wet loose slides could release naturally in the afternoon if sustained rainfall occurs. The timing of the release of wet slabs is difficult to predict, and terrain where these avalanches could occur should be given a wide margin of safety. Be very suspect of slopes where dry, old snow is melting for the first time.
Dry slab avalanches could occur in some areas above 9,000 feet. As the day warms, skiers and riders will be increasingly likely to trigger these slabs in steep, avalanche-prone terrain. These dense slabs could reach depths of 30 inches by this evening.
West-southwesterly flow aloft and an upper level low pressure system moving inland from the Pacific Northwest will bring colder, unstable Pacific moisture to the region through Sunday. The rain line will drop to near the valley floor overnight before climbing during the day, and six to twelve inches of new snow could accumulate in the mountains by Sunday evening. Southwesterly to westerly ridgetop winds will increase to 25 to 40 miles per hour.The general avalanche hazard is expected to be Considerable in the higher elevations on Saturday. As temperatures cool, rain changes over to snow and winds increase, the primary threat of avalanche activity will transition from wet slides back to dry slab avalanches in the mountains. The chance for skiers and riders to trigger newly developed winds slabs up to two feet in depth will be on the increase through the day at the higher elevations. In terrain where a substantial snowpack remains at the lower elevations, the threat of shallow wet slides will continue.
