In steep, wind loaded terrain at the mid and upper elevations, skiers and riders could trigger small to large wind slabs. Be on the lookout for hard, drummy deposits of wind transported snow, and give them a wide berth if traveling in avalanche terrain. As the day warms, these slabs may become more susceptible to failure. The occurrence of a low probability/high consequence persistent deep slab avalanche cannot be ruled out. With overnight temperatures above freezing at the mid and lower elevations, wet slides might become possible on sunlit aspects as the day warms if the forecasted cloud cover does not materialize.
Since midday on Saturday, southwesterly to westerly ridgetop winds ranged from 30 to 45 miles per hour with gusts up to 59. Above 7,500 feet, these strong winds have scoured windward slopes and formed dense wind slabs in leeward terrain. Skiers and riders could trigger these slabs, along with older wind slabs, to depths of one to three feet in steep, wind loaded terrain.
A slight chance remains for backcountry travelers to trigger persistent deep slab avalanches above 7,500 feet. With depths ranging from three to seven feet, these avalanches are likely unsurvivable. A snowmobiler impacting a shallow portion of the snowpack will be the most likely scenario for triggering one of these destructive avalanches. A cornice drop or a moving wind slab could also initiate one of these slides.
Snow will develop from north to south as a powerful storm system moves through Western Wyoming. Snow banding may create localized areas with snowfall rates of two inches per hour. Winds will increase to speeds of 35 with gusts to 50 miles per hour and veer from the southwest to the northeast. Areas of blowing and drifting snow will develop overnight and continue until skies clear on Monday evening. Temperatures will drop into the single digits in the mountains and into the teens at the lower elevations. Fresh wind slabs will develop and gain volume as the day progresses. In areas that are favored by the most intense snowfall rates these slabs could grow to depths of two feet and are likely to become sensitive to human triggers. Natural releases are possible.A deep slab avalanche was observed to have occurred on a northwest aspect of Palisades Peak in the Snake River Range yesterday morning. The last deep slab avalanche in our forecast region was observed January 19 and occurred on a northeast aspect of Mt. Taylor. This type of avalanche may still be possible in isolated locations. Those locations are likely to be in an active avalanche path and could be triggered by a snowmachine that crosses a thin area of a persistent slab or by the failure of a large cornice. At the higher elevations the new snow and strong winds may briefly increase the general avalanche hazard to considerable. The general avalanche hazard is expected to be low but increasing with respect to new snow hazards at the lower elevations.
