This technical note presents a combination of isohyetal map, kinematic wave, and rational methods for estimating flash flood synthetic hydrographs in and regions. They are combined in a logical sequence for the calculations of time of concentration and synthetic flood hydrograph. This empirical approach relates flood peaks to the average temporal and areal intensities of storm rainfalls. The application of the methodology is presented for two and region wadis in the central western part of the Arabian Peninsula. Hydrograph peaks yield practically reliable estimations of the observed flood magnitudes from individual storms.