Fourteen inches of new snow with over an inch of moisture has fallen in the mountains since about 6 PM last night. Old snow surfaces are slick and exist on west through north to east facing aspects at the upper elevations and on steep north facing terrain at the mid elevations. Human triggered avalanches are likely in steep terrain on those old snow surfaces. These avalanches could be large enough to bury or seriously injure a person. Avalanches are unlikely at the lower elevations and in areas at the mid and upper elevations where last night's new snow has accumulated on bare ground.
West-northwest to west-southwest winds will continue to load leeward aspects. Soft slabs avalanches up two feet in depth could be human triggered on slick old snow surfaces.
The National Weather Service has issued a winter storm warning. The center of a low pressure system is moving down the west coast towards Seattle. As this system digs into northern California it will begin to direct Pacific moisture into the region. Moderate to heavy snowfall is expected to become widespread in the mountains on Friday and continue into Saturday. The freezing level is initially forecast to be around 6,500 feet and will lower as colder air moves in behind a cold front on Saturday. The mountains are expected to receive another 3 to 7 inches of new snow overnight and another 7 to 11 inches during the day on Friday. A mix of rain and snow is likely in the valleys. Temperatures in the mountains will be in the 20s tonight and will rise into the 30s during the day. Winds will be from the west-southwest at 18 to 22 miles per hour with higher gusts.The general avalanche hazard is expected to be MODERATE at the upper elevations (9,000 to 10,500 feet) on Friday and will be increasing as the day progresses. In steep terrain dense wind slabs one to three in depth could be human triggered on slick old snow surfaces. Avalanches are unlikely in areas where the recent new snow lies upon bare ground and on all aspects below an elevation of 8,000 feet.
