The general avalanche hazard is CONSIDERABLE above an elevation of 8,500 feet and MODERATE below that elevation. Dense surface slabs lie upon persistent weak layers comprised of buried surface hoar. These slabs have gained volume and could be triggered on approach, after being crossed multiple times and on lower angle terrain than one might expect. Two days ago a guide was caught, carried and fully buried in the Snake River Range. He was uncovered by companion guides and was not injured. The potential for humans to unintentional trigger dense slab avalanches with severe consequences is significant.
At the mid and upper elevations dense surface slabs up to 18 inches in depth could be human triggered in steep terrain on buried layers of surface hoar. In isolated areas some potential may exist for these slabs to step down to deeper layers of buried surface hoar with depths to three feet.
( Discussion is generated from the previous day's afternoon forecast. )The moist west flow will continue to bring periods of snow to the region with the heaviest snowfall expected in the Teton Range. Lesser amounts are expected on Togwotee Pass and over the Salt River and Wyoming Ranges. The snow will decrease in intensity but periods of light snowfall should continue through Monday. Winds will be west to west-northwest at speeds of 25 with gusts to 40 miles per hour overnight and slowly decrease to speeds to 15 to 20 miles per hour by Monday evening. Temperatures will drop into the teens and 20s. The persistent weak layers of surface hoar covered by the recent new snow are a game changer with respect to the short and long term stability of our snowpack. Due to the spacial variability of the buried surface hoar suspect slopes or portions of suspect may be remotely triggered, may be triggered after being crossed by multiple persons or may be stable. Cooler temperatures and decreasing snowfall will decrease the sensitivity of these slabs to humans triggers, however today's additional moisture have increased the size and density of these avalanches. While the likelihood of triggered is expected to decrease the potential for humans to unintentionally trigger a slab avalanche with severe consequences is significant. The general avalanche hazard is expected to be MODERATE on Monday, however the assessment of this hazard is inherently problematic and therefor unintentionally triggered slab avalanches are possible with potentially severe consequences.
