Even in areas where annual precipitation is predicted to decrease through the 21st century (e.g., the Midwest), the number of extreme rainfall events is predicted to increase basically everywhere.
Note: "extreme" rainfall event definitions vary, but most use a threshold percentile of daily precipitation amounts (e.g., a 24-hour rainfall exceeding the 98th percentile of all 24-hour rainfalls at a given location in a year).
http://www2.ucar.edu/atmosnews/news/124334/extreme-downpours-could-increase-fivefold-across-parts-us
Note: "extreme" rainfall event definitions vary, but most use a threshold percentile of daily precipitation amounts (e.g., a 24-hour rainfall exceeding the 98th percentile of all 24-hour rainfalls at a given location in a year).
http://www2.ucar.edu/atmosnews/news/124334/extreme-downpours-could-increase-fivefold-across-parts-us