An atmospheric river laden with water vapor coming out of the tropics will slam into the Sierra Nevada this weekend and early next week, bringing as much as 10 feet of new, wet snow to the higher elevations, according to the National Weather Service in Sacramento. It is the second of two channels of water-filled clouds that will strike Northern California. By Thursday morning, the first river of water vapor brought nearly seven feet of new snow to Squaw Valley, four feet to Kirkwood and almost as much to Bear Valley.