The potential for humans to trigger dense slab avalanches one to two feet in depth persists in steep, upper elevation avalanche paths. As the day progresses warming temperatures and loading from southwest winds will increase the sensitivity of these slabs to human triggers. Avalanches are unlikely at the mid elevations where snow depths are shallow. Areas of bare ground exist at the lower elevations. Grand Targhee Resort is preparing its slopes for a Friday opening and therefor the resort is closed to uphill travel during the next three days.
Dense surface slabs lie upon a persistent weak layer of buried surface hoar that sits atop a firm crust. These slabs are most likely to be triggered on steep northerly aspects at the upper elevations and in areas that have experienced recent wind loading.
The low pressure system spinning just off of the Pacific Northwest Coast will quickly move inland overnight and then move quickly towards Western Wyoming. Snow is expected to develop in the morning, become widespread by midday and continue into Wednesday evening before gradually decreasing and tapering off behind a passing cold front. Accumulations of three to seven inches are possible in the mountains. Temperatures on Wednesday will rise to near freezing by noon at 9,000 feet and then fall into the 20s in the afternoon. Winds will be gusty at 18 to 25 miles per hour with gusts to 35 miles per hour and veer from the south in the early morning hours to the west by evening.Mild temperatures overnight and in the morning hours will continue to settle the snowpack. At the upper elevations areas of instability persist on steep northerly exposures that are prone to avalanche activity. Some potential may remain for humans to trigger pockets of dense slab one to two feet deep. The general avalanche hazard is expected to be MODERATE at the upper elevations and LOW below an elevation of 9,000 feet. In order to prepare its slopes for opening on Friday, Grand Targhee Resort will be closed to uphill traffic on Wednesday and Thursday.
