With onshore flow and available moisture, showers will move through the region this evening. Snow levels will be around 4,500′ so this will mean rain showers for the Valleys, and a rain/snow mix for the Basin. More importantly, a much stronger system will be moving into the region tomorrow dropping snow levels and bringing high snow accumulations to the Cascades. A winter storm warning is in place for heavy snow for both the Cascades and Siskiyous through Friday evening. A winter weather advisory is in effect for the Valleys into Saturday morning as well.
Showers will begin by early afternoon as the cold front nears. Snow levels will be around 4,000′ tomorrow afternoon and quickly drop with the passing of the front. By about 3pm precipitation will be widespread and intensity will begin to strengthen among the showers. Precipitation will fall as snow for the entire duration of the storm in the higher elevations, while it will start as rain and possibly mix with snow or even change to snow in the Foothills by Saturday morning.
Upsloping winds will allow for a good foot of snow to fall in the Cascades, with even higher amounts further north. Crater Lake could see as much as 18″ by Saturday morning. Heavy snow will allow for snowfall rates to exceed 1″ an hour, in fact it’s quite possible 2-3″ of snow fall per hour. The Siskiyou’s could see roughly 3-8″, with locally higher amounts.
Snow levels are going to drop to 2,000′ and even 1,500′ is possible in some locations. This will allow for snow to reach the Valley floor, so 1-3″ is possible in the Foothills by Saturday morning.
Winds will gust to about 40mph along the Coast and in the Basin. The higher elevations of the Valleys will gust to about 30mph. Sneaker waves are going to be a threat tomorrow afternoon & evening along the Coast. Wave heights will reach 20 to 25 feet so folks along the Coast should stay away from the water at all costs.