Flash Flood Guidance products are issued on a twice-daily basis at about 11 a.m. and 9 p.m. Central Time. National Weather Service Weather Forecast Offices (WFOs) use this guidance when issuing flash flood watches and warnings to the public. It should be noted that these values are meant to be used only as guidance. Topography and/or urbanization in some areas are also contributing factors to flash flooding.
Flash Flood Guidance is used to predict the occurrence of flash flooding in a specific area based on specified rainfall amounts within a given duration of time. The River Forecast Center (NCRFC) calculates and issues products with guidance values for 1, 3 and 6-hour rainfall totals for all counties within the NCRFC region.