Report of systematic comparisons of rainfall simulations produced by numerical weather predication models (Eta) used in Egypt, Ethiopia, and Sudan, in order to achieve uniform testing and improvement of model performance. The emphasis was on the general process of how to test and improve a numerical rainfall prediction model, rather than the specifics of the Eta model. This work was carried out as part of the World Bank supported Flood Preparedness and Early Warning Project Phase I (FPEW I), implemented by ENTRO from 2007 – 2010.