Abstract: A methodology was required for estimating flow in ungaged drainages. An analysis of floods in the western Mojave Desert showed that the largest events on basins below 1,500 meters MSL were caused by mesoscale convective complexes (cloudbursts). Regional hydrologic methods were not applicable since peak flow measurements were inaccurate due to sediment bulking and alluvial fan and channel losses. A methodology was developed with determined representative spatial and temporal distributions of precipitation from analysis of historic cloudbursts in California Nevada and Arizona. Templates of spatial distribution of point gage statistics were used in the HEC-1 hydrologic model to simulate peak flows. A comparison was made between simulated peak flows and observed peak flows at gages.