Abstract:The effect of sea breeze front on a severe local thunderstorm occurring on July 29, 2013 in Ningbo was studied in this paper. Diagnostic analysis was performed using the observational data from the conventional meteorological stations and the encrypted data from the ground automatic weather stations in Zhejiang Province, the new generation Doppler weather radar, and the NCEP GFS analysis data. WRF was adopted to carry out numerical simulations. Analysis of observational data shows that the severe thunderstorm occurs in a stable atmosphere, and the sea breeze front associated with mesoscale convergence line plays the most important role. The mesoscale sea breeze front in the boundary layer can be identified by the narrow-band echo in the Doppler radar. As the sea breeze front advances inland, the temperature falls and the humidity rises, which can be captured by the meteorological stations. The numerical simulation with WRF can well reproduce this severe thunderstorm process, and capture the spatial and temporal characteristics of low-level sea breeze front circulation as well as the high-level backflow in Ningbo. Geostrophic forcing associated with the sea breeze front frontogenesis strengthens the secondary circulation, favoring ascending motions in the convergence line of the east and west wind. Sensitivity simulation suggests that the sea-land thermal contrast is an important factor that influences the precipitation intensity and the vertical and horizontal circulation of sea breeze front during the thunderstorm.