This paper applies ECMWF refined net numerical forecast data, AWOS data, wind profiler data as well as regular data to southeast gale forecasting and diagnostic analyzing in Urumqi southern suburbs in spring, in order to reveal the cause of occurrence and the maintaining of southeast gale so as to understand the meaning of the ECMWF refined net numerical forecast data for southeast gale forecasting and increase accuracy rate of southeast gale forecasting. The analysis indicates that the southeast gale from Urumqi southern suburbs to Dabancheng was caused by the Mongolian high pressure moving southward. The gale was resulted from the east-west pressure gradient, terrain of Urumqi with narrow tube direction and the slope gravity. The information of 850 hPa wind, lO-meter wind, sea level pressure, 2-meter temperature were very useful for the forecast of beginning and end of southeast gale , wind grade and the area hit by the wind. ECMWF refined net numerical forecast data make up the lack of spatial and temporal distribution of data that help the forecasters more clearly understand the occurrence and development of the weather system.