(Updated Monday) Flash Flood Warning Published 12 Minutes After the Grand Canyon Flash Flood
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 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 Canyon Village. The storms, as shown in the image above, were moving east northeast.
Back at WeatherData, Inc. we had a contract with a major flood control district in Arizona. Their hydrologist frequently emphasized, "if you wait [to warn of a flood] until the water hits the ground, it is too late." That meant you had to make a short term forecast based on radar in order to anticipate the heavy rain before it fell in order to have an effective warning. That did not seem to occur in this case.
Of course, the above is a preliminary cursory overview of what occurred. This would be a case where a National Disaster Review Board would be incredibly helpful by doing a comprehensive review. The information they learn and their recommendations would help the National Weather Service provide better warning services in the future.
Congress?
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The update from the Park Service was just posted:
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