In steep, wind loaded terrain above 7,500 feet, backcountry travelers 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 near freezing below 9,000 feet, wet slides might become possible on sunlit aspects as the day warms if the forecasted cloud cover does not materialize.
Since yesterday afternoon, Mount Coffin recorded westerly ridgetop winds ranging from 45 to 67 miles per hour with gusts up to 83. Above 7,500 feet, these very 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 8,000 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.
( Discussion is generated from the previous day's afternoon forecast. )Cloud cover will increase overnight ahead of the next Pacific storm system, and skies will become overcast by morning. This system will move in from the northwest to the southeast, and moderate to heavy snowfall could begin by Sunday afternoon. Overnight lows in the mountains will be in the low 20s before rising into the upper 20s during the day. Valley temperatures will drop into the mid-20s tonight and then rise into the mid-30s in the afternoon. Ridgetop winds will back to the southwest and decrease to 15 to 25 miles per hour.The general avalanche hazard is expected to be Moderate above 7,500 feet on Sunday. Up there, skiers and riders could trigger small to large wind slabs in steep, wind loaded terrain. In the afternoon, new shallow winds slabs will begin to form on a variety of snow surfaces, which include wind pack, sun crusts and settled snow. The low probability/high consequence event of a persistent deep slab avalanche cannot be ruled out. With below freezing temperatures overnight at all elevations, the threat of wet slides will abate, and avalanches will be unlikely below 7,500 feet.
