Dangerous avalanche conditions continue. Three nights of above freezing temperatures at all elevations and warm daytime temperatures have resulted in a weak and unsupportive snowpack. Wet loose and wet slab avalanches are possible today. These wet slides could release naturally and will be easily triggered by backcountry riders and skiers trying to navigate steep terrain. Although most likely to occur at the mid and upper elevations, wet slides could still release at low elevations in steep north facing terrain where snow has not yet melted. Backcountry travelers are encouraged to get in and out of the mountains early this morning and to remember that wet slides can run long distances and impact trails below them. Be wary of travelling under any large avalanche path today.
Wet loose avalanches will be likely in steep terrain today. These may occur naturally and will be easily triggered by skiers and riders. The likelihood of triggering will increase as rising temperatures and sunlight impacts snow surfaces. These avalanches have the potential to entrain significant amounts of snow.
Water moving through the snowpack has the potential to further weaken old snow layers that were problematic earlier in the season. Although less likely than wet loose slides, if initiated, these slabs could be large with depths in the 1-3 foot range. At the high elevations, these slabs could involve a combination of dry and wet snow.
Moisture approaching in southerly flow will begin to bring rain and snow showers to the area tonight. The rain/snow line will initially be around 10,000 feet and lower overnight to around 8,000 feet. Accumulations will be in the trace to 1” range in the higher elevations. Snow showers will continue during the day with an additional 1-3” by evening. Temperatures overnight will remain mild, with lows in the mid thirties between 8,000-9,000 feet. A cold front will push through during the day tomorrow, bringing temperatures down to the low thirties in this elevation band. Winds will be out of the southwest tonight at 15-20 mph and veer to the northwest at 10-15 mph during the day tomorrow.Prior to this significant warm up, the focus was on persistent weak layers that had activated and were producing snowmobile and skier trigerred avalanches above 8,500 feet on the north half of the compass primarily in the Southwest Trails forecast area. A similar set up exists in the Tetons and on Togwotee Pass, but there has been much less activity reported in those areas. While the persistent avalanche problem remains a concern, this warm up has tested those layers. With cooling and freezing expected over the coming days, this avalanche problem will become unlikely. Tomorrow expect lingering snowpack issues related to this recent warm up. The avalanche danger will be Moderate. Wet loose avalanches will remain possible in very steep terrain. The likelihood of triggering wet loose, wet slab and persistent slab avalanches will decline as temperatures cool. New snow during the day tomorrow will not be enough to create an avalanche problem on its own.
