About Flash Flood Guidance:
*** ATTENTION FFG USERS ***
Gridded FFG can be downloaded at http://www.srh.noaa.gov/ridge2/Precip/gffgshp/
Gridded Flash Flood Guidance is on the scale of a 4 km by 4 km grid allowing for flash flood guidance at a sub-county level.
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.