The primary purpose of the Flash Flood Guidance (FFG) system is to provide real-time guidance products to forecasters worldwide pertaining to the threat of potential small-scale flash flooding over large regions with high resolution. The system provides the necessary products to support the development of warnings for precipitation induced flash floods through the use of real time in situ and remotely sensed data, numerical spatially distributed land surface hydrological models, and mesoscale numerical weather prediction models. The FFG system consists of regional and country-specific systems that allow the incorporation of local information in the system products and the development of regional cooperation in hydrometeorological forecasting. Gauge-adjusted satellite-based rainfall estimates (The satellite-based rainfall estimates are provided to HRC for the operational FFG systems by NOAA. Outputs from the Global HydroEstimator are provided by NESDIS and the CMORPH by CPC.). Also, when available, radar-rainfall estimates provide real time information on precipitation. The system is complemented with an extensive training program and is designed to allow forecaster adjustments to the system products in real time on the basis of local experience and local up-to-the-minute information not incorporated in the system products. The design aims at the reduction of the loss of life and human suffering from the devastation caused by flash floods, and it is consistent with an end-to-end forecast response process.
Advances with respect to the basic FFG system capability include the ability to produce real time nowcasts of landslide threat occurrence based on pre-computed high resolution susceptibility maps and real-time estimated thresholds of the FFG-produced precipitation and soil water. The FFG systems are also being enhanced with riverine routing and reservoir simulation capability and are now able to provide real-time simulated and forecast hydrographs for pre-specified locations on the large regulated rivers of a region.
Example real-time product outputs from FFG systems in Southern Africa and South Asia.