A 1-inch rainstorm deposits 27,154 gallons on one acre, so during this storm, a city the size of Atlanta receives 2.28 billion gallons of water.
11 trillion gallons sounds possible if they continue to get widespread storms.
California has an area of 163,696 sq mi. That is 104,765,440 acres. 1” over the entire state would be 2,844,800,757,760 gallons. Almost 3 trillion gals per inch.