Dangerous avalanche conditions will be developing at the mid and upper elevations today. Strong winds are forming slab avalanches on a variety of old snow surfaces. Expert evaluation of terrain, the snowpack and rapidly changing conditions will be essential for safe travel in avalanche terrain. Shallow snow depths exist at the lower elevations and rain is forecast below an elevation of 7,000 feet where the avalanche hazard will remain LOW.
At the mid and upper elevations strong southwest winds are creating dense wind slabs on leeward aspects. These slabs will gain depth and volume and become more sensitive to human triggers and natural releases as the days progresses. Slabs depths could grow to two feet in the later afternoon and evening hours.
( Discussion is generated from the previous day's afternoon forecast. )The National Weather Service has issued a Winter Strom Warning from midnight tonight through Friday afternoon. The leading edge of a major winter storm will move into western Wyoming tonight. Like most of the storms that have hit us this season this storm will favor the Teton, Togwotee Pass and the northern portion of the Greys River area. The freezing level is anticipated to rise to an elevation of 7,000 feet by morning. Rain is likely in the valleys, a mix of rain and snow is expected between 7,000 and 8,000 feet. At the higher elevations snowfall will develop overnight and intensify during the day and into the evening. Upper elevation accumulations are forecast to be 4 inches by noon, another 6 inches by midnight with another 9 inches by noon on Friday. West to southwest winds at 25 to 35 with gusts to 50 miles per hour will accompany the snowfall. Temperatures will be in the mid and upper 20s at 10,000 feet and in the 30s and 40s in the valleys.New snow and winds will increase the avalanche hazard as the day progresses. The heaviest snowfall is expected on Thursday evening and into Friday. New wind slabs will form on leeward aspects and gain depth and volume as this storm develops and intensifies. The general avalanche hazard is expected to rise to MODERATE during the day and is likely to increase to CONSIDERABLE in the most favored locations as snowfall intensity increase to rates of over an inch per hour by evening.
