Analysis of Typhoon-Tornado Weather Process in Leizhou Peninsula

On the morning of November 11, 2013, a tornado occurred in Xuwen County, Zhanjiang City, about 350 km away from the center of Typhoon No.30 “Haiyan”, with the intensity of tornado event was rated EF1. Based on the disaster investigation, conventional observations data, surface automatic weather station, a Zhanjiang S-band Doppler radar and so on, the environmental background and radar echo characteristics of tornado occurrence and development are analyzed. The results show that the tornado was generated southeast jet convergence zone between the subtropical high and typhoon. The atmospheric conditions show that typhoon-tornado occurred in an environment with medium convective available potential energy, weak convective inhibitory energy, low elevation condensation height, strong 0-6 km and 0-1 km vertical wind shear and large low-level relative humidity. The surface mesoscale convergence line and micro vortex occurred before the tornado. The difference between the temperature of the ground cold pool caused by the sinking airf low of the tornado storm and the environment is about 1-4 ℃ and the smaller temperature difference is conducive to the formation of tornado. The convective storm which produced tornado was mini supercell storm with low center of mass, which has the characteristics of hook echo, inf low gap, moderate to strong mesocyclone and TVS in the lower layer. The mesocyclone and TVS have an extension height below 2 km. Before the tornado occurs, the intensity of the mesocyclone increases, the diameter decreases and the base height decreases. The TVS appears about 24 minutes earlier than the tornado.