Dangerous avalanche conditions are developing this morning above 8,000 feet. As the day progresses, the avalanche hazard will continue to increase as abundant snowfall and strong southwesterly to westerly winds add depth and volume to new wind slabs. Throughout the day, skiers and riders will be increasingly likely to trigger these slabs on steep, leeward slopes. Natural activity will also become possible. Travel in avalanche terrain will require expert snowpack and terrain evaluation skills. Monitor the impact of the storm system and be willing to alter your travel plans if conditions warrant. Below 8,000 feet, backcountry travelers could trigger small pockets of wind slab in steep, wind loaded terrain. As accumulating snowfall adds weight to persistent weak layers of faceted snow near the base of the snowpack, the unlikely event of a persistent deep slab avalanche will increase slightly.
By this evening, developing wind slabs could reach depths up to 30 inches above 8,000 feet. As these slabs increase in size throughout the day, the chance for human triggering and natural activity will be on the rise in steep, wind loaded terrain. Below 8,000 feet, backcountry travelers could trigger similar slabs to depths up to 18 inches on very steep, leeward slopes.
( Discussion is generated from the previous day's afternoon forecast. )The National Weather Service has issued a Winter Storm Warning beginning at 8 PM tonight and continuing through 11 PM on Sunday. The flow aloft will back to the west, strengthen and bring a stream of Pacific moisture to the region. This scenario will produce moderate to heavy snowfall tonight and through the day on Sunday with mountain accumulations of 12 to 18 inches by tomorrow evening. Westerly ridgetop winds will increase to 30 to 45 miles per hour. Mountain temperatures will slowly rise overnight before reaching a high near 20 during the day.The general avalanche hazard is expected to increase to Considerable above 7,500 feet as dangerous avalanche conditions develop. Abundant snowfall and strong winds will continue to add depth and volume to wind slabs in leeward terrain. As the day progresses, skiers and riders will be increasingly likely to trigger these slabs on steep, avalanche prone slopes. These slabs could reach depths in excess of three feet by tomorrow evening, and natural activity will also be possible. Travel in avalanche terrain will require expert snowpack and terrain evaluation skills. Monitor the impact of the storm system and be willing to alter your travel plans if conditions warrant. Below 7,500 feet, backcountry travelers could trigger similar slab avalanches up to 18 inches deep in steep, wind loaded terrain. There, the general avalanche hazard is expected to increase to Moderate.The Wyoming Department of Transportation will be closing Teton Pass for avalanche mitigation at noon on Sunday. Parking will also be prohibited between the Idaho state line and the Wilson gate beginning at 8 PM tonight.
