Analysis of a tornado-like severe storm in the outer region of the 2007 super typhoon Sepat

When super typhoon Sepat came close to the Fujian coastline on the night of 18 August 2007(coded as 0709 in Chinese convention), an associated tornado-like severe storm developed at 2307-2320 Beijing Standard Time in Longgang, Cangnan County, Wenzhou Prefecture, Zhejiang Province approximately 300 km away in the forward direction of the typhoon. The storm caused heavy losses in lives and property. Studying the background of the formation of the storm, this paper identifies some of its typical characteristics after analyzing its retrieval of Doppler radar data, vertical wind shear and so on. Synoptic conditions, such as unstable weather processes and TBB, are also studied.