Abstract:Using conventional observational data, surface meteorological observation data and Doppler radar data, the weather characteristics and causes of the gust front in North China on 4 August 2013 are analyzed. The results indicate that the configuration of ground front and forward tilting trough is the favorable large scale circulation background of the gust front. Between the outflow cold air of surface mesoscale high and environment wind forms a mesoscale convergence line, which makes the convective activity get intensified, causing new thunderstorms to generate or be strengthened. In the mature stage, squall line has distinct characteristics, and develops to the right. At first, the gust front forms in front of severe thunderstorms of the squall line. The stronger the squall line, the stronger the gust front. The maintainance of the gust front relies mainly on the continued sinking airflow of the storm. The gust front weakens after the sinking airflow drops off. Meteorological elements have dramatic changes as the squall line and gust front are passing through the area. When the system develops stronger, the variation of meteorological elements of gust front is greater than that of squall line, but is weaker in the rest time. After the squall line gets weakened, the gust front still also maintains for a period of time, which needs to be observed more carefully.