DEVELOPMENT OF EARLY LOCAL HEAVY RAINFALL FORECAST TECHNIQUE AT OSAKA CITY

Abstract

 In Japan, flooding damage in urban areas caused by local heavy rainfall has increased in recent years. It is of great importance to improve the precision of forecasting local heavy rainfall. However, the present weather forecasting system cannot forecast the local heavy rainfall well in advance since local heavy rainfall has small scale and builds up suddenly. In this study, therefore, we develop two early local heavy rainfall forecast techniques at Osaka City. One is the weather index technique, and the other is the numerical weather forecasting technique that assimilates the X-band multiparameter radar (X-MP). As a result, we can forecast local heavy rainfall earlier by the weather index technique, and we can express the movement, strength, and detailed structure of local heavy rainfall using the numerical weather forecasting technique by assimilating X-MP.