Decision Support Weather Briefing – National Weather Service (.gov)

Decision Support Weather Briefing  National Weather Service (.gov)

This briefing is updated each Monday and Friday, and more frequently during hazardous weather events. Flash Flood Guidance (FFG) provides a general indication of the amount of rainfall evenly distributed over various durations (in hours), necessary to cause small streams to overflow their natural banks. During heavy rainfall, accurate interpretation of the guidance consists of the combination of rainfall that has already occurred plus any additional rainfall that can be confidently expected to fall over the same location in the immediate future.

It should be noted that FFG values represent estimates of average soil moisture and stream flow conditions. Flooding may occur with less rainfall than indicated in areas of high rainfall intensities, impervious surfaces, or steep slopes. Hydrographs (showing stages and flows over time) are available through the National Water Prediction Service (NWPS) by clicking site names. Mouse over each site to display hydrograph. Hydrographs are available through NWPS by clicking site names.