About Flash Flood Guidance:
National Weather Service (NWS) River Forecast Centers routinely issue Flash Flood Guidance throughout the day for
every county in their area. The river forecast centers determine 1- 3- and 6-hour flash flood guidance values for
all counties, and 12- and 24-hour values for parts of the eastern United States. The NWS Weather Forecast Offices
use this guidance when issuing flash flood watches and warnings to the public.
Flash Flood Guidance estimates the average number of inches of rainfall for given durations required to produce
flash flooding in the indicated county. These estimates are based on current soil moisture conditions. Note, in
urban areas, less rainfall is required to produce flash flooding.