This research aims to study the relashionship between climatic large scale synoptic patterns and rainfall in khorasan region. Fuzzy inference system (FIS) was used in this study to predict rainfall in the period between December to May in the region. soft computing is an innoviate approch to constract computationally intelligent systems that are supposed to posses humanlike experties within a specific domain adopt themselves and learn to do better inchanging environment and expliend how they make decision unlike conventional artificial intelligence thechniques the guiding principel of soft computing is to exploite tolerance for impression uncertainly , robustness, partial truth to achive tractibility and better ropport with reality.

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