According to the Grand Canyon office of the National Park Service, the major flash flood occurred Saturday at 2:30 pm MST (4:30pm CDT).  Unfortunately, the National Weather Service's flash flood warning was not issued until 2:42pm, twelve minutes after the flash flood occurred. The worst flooding was apparently in the Bright Angel Creek area. While this was a fast developing flood situation, there were clues. The National Weather Service excessive rainfall forecasting group had put that area under what some would call a flood alert. The image is part of a detailed meteorological (technical) discussion regarding the enhanced risk of flash flooding within the purple area. It was issued at 11:13am Arizona time, about three hours before the flood.  The radar showed torrential rain (for Arizona) occurred starting roughly 20 minutes before the flood. Here is the radar three minutes before the flood (4:27 CDT = 2:27 pm MST). The area of interest is about 5 miles northeast of Grand Ca...