Yesterday, a skier triggered a shallow wind slab on a very steep, south east facing slope at an elevation just over 11,000 feet. While this slide was small, the skier was caught and carried out of sight. Luckily he was uninjured. Similar slides are possible today at the mid and upper elevations, and the likelihood of triggering these slabs will increase during the day as new snow accumulates and temperatures warm, especially if precipitation intensity remains heavy through the afternoon. As the day progresses, warming temperatures and a rising rain line will also increase the likelihood of wet slides. Monitor daytime warming, and transition to cooler terrain before the old snow becomes unsupportable.
In steep, avalanche prone terrain above 8,500 feet, the chance for skiers and riders to trigger wind slabs one to two feet in depth will be on the increase as the day warms. Be wary of terrain where dry snow is transitioning to wet snow, especially in areas that were shaded during the heart of winter and are melting for the first time of the season.
The next in a series of Pacific shortwaves will bring increasing precipitation intensity through the day on Saturday. Rain is expected below 8,000 feet overnight, and the rain line will increase in elevation during the day. Overnight lows in the mountains will be in the mid-20s before rising into the mid-30s in the afternoon. Southwesterly ridgetop winds will range from 10 to 20 miles per hour.The Wyoming Department of Transportation is planning to close Teton Pass at 9 AM on Saturday due to the threat of wet slides. They will reassess conditions at 3 PM. The primary factors for the avalanche hazard on Saturday will be 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 could increase to High in the afternoon. Wet slabs, which could release naturally, will be the primary concern on Saturday. The timing of the release of significant wet slabs is difficult to predict, and terrain where these avalanches could occur should be given a wide margin of safety. Glide avalanches might also release in favored terrain, and the chance of triggering dry slab avalanches up to two feet in depth will increase above 9,000 feet 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.
