Look at the heavy rain that’s expected for S. California. A heavy rain like this will not only cause some flooding, but mudslides/rockslides are possible.
The Sierra Mountains will once again see heavy snowfall. I checked some Western ski area season snowfall totals. Mammoth Mt. is up to 430″ for the winter – that’s 68″ more than they got all last winter. The base at the lodge is 178″. At the top of the mountain at 11,053 ft. elevation, the snow base is 340″ (28.3 feet!). It’s the most snow Mammoth Mt. has seen since 2010-11. Other season snowfall totals: 484″ Kirkwood CA, 482″ Alpine CA, 476″ Squaw Valley CA, 464″ Heavenly CA, 434″ Jackson Hole WY, 340″ Alta UT, 339″ Wolf Creek, 326″ Timberline OR, 311″ Alyeska AK, 300″ Whistler BC Canada.
This pic. of the Oroville Dam was taken 2/11. You can see the water going over the spillway. It washed out the road that you see in the pic. The main spillway (which was damaged is in the foreground. The dam was completed in 1968 and at 770 feet, it’s the tallest dam in the U.S. When full, the reservoir contains 3.5 million acre feet of water. It’s very deep with a relatively small surface area (good for storing water). the 3.5 million acre feet compares volume wise to Lake St. Clair that has 2.77 million acre feet. You can see that if the dam failed, that’s a lot of water heading down the Feather River to Yuba City, Maryville and eventually Sacramento. They have been trying to lower the lake level at the rate of 8 feet per day. They have had 125 construction crews that can drop 1,200 tons of rocks until the spillway area in an hour. Two helicopers are in use. The nearly 200,000 people evacuated have been allowed to return home…that’s about the same number of people that live in G.R. Could you imagine the traffic jams if the entire city of G.R. was told to leave town all at once. The overnight run of the GFS model gives 9.6″ of rain to Oroville CA in the next 6 days!