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Lanqiang Bai, Zhiyong Meng, Ling Huang, Lijun Yan, Zhaohui Li, Xuehu Mai, Yipeng Huang, Dan Yao, and Xi Wang

Abstract

This work presents an integrated damage, visual, and radar analysis of a tropical cyclone (TC) tornado that has not been documented as detailed as midlatitude tornadoes. On 4 October 2015, an enhanced Fujita 3 (EF3) tornado spawned into Typhoon Mujigae and hit Foshan, Guangdong Province, China. This tornado was generated in a minisupercell ∼350 km northeast of the TC center and lasted about 32 minutes, leaving a southeast-to-northwest damage swath 30.85 km long and 20–570 m wide. Near-surface wind patterns and the size of the tornado, juxtaposition of the condensation funnel with the damage swath and radar signatures, and consistency between near-surface wind speed estimated from visual observations and that estimated using EF scale were revealed based on ground and aerial surveys, radar and surface observations, photographs, and tornado videos. Tornado videos showed two occurrences of vertical subvortices followed by the formation of a horizontal vortex. Some features of the tornado, the parent supercell and mesocyclone, and the convective environment were compared to their U.S. counterparts. This work provides a case review of a tornado with the most comprehensive information ever in China. Damage indicators used to estimate the tornado intensity in this Chinese case were compared with those in the United States, demonstrating the potential applicability of the EF scale in tornado damage surveys outside the United States.

Open access
Kun Zhao, Mingjun Wang, Ming Xue, Peiling Fu, Zhonglin Yang, Xiaomin Chen, Yi Zhang, Wen-Chau Lee, Fuqing Zhang, Qing Lin, and Zhaohui Li

Abstract

On 4 October 2015, a miniature supercell embedded in an outer rainband of Typhoon Mujigae produced a major tornado in Guangdong province of China, leading to 4 deaths and up to 80 injuries. This study documents the structure and evolution of the tornadic miniature supercell using coastal Doppler radars, a sounding, videos, and a damage survey. This tornado is rated at least EF3 on the enhanced Fujita scale. It is by far the strongest typhoon rainband tornado yet documented in China, and possessed double funnels near its peak intensity.

Radar analysis indicates that this tornadic miniature supercell exhibited characteristics similar to those found in United States landfalling hurricanes, including a hook echo, low-level inf low notches, an echo top below 10 km, a small and shallow mesocyclone, and a long lifespan (3 h). The environmental conditions—which consisted of moderate convective available potential energy (CAPE), a low lifting condensation level, a small surface dewpoint depression, a large veering low-level vertical wind shear, and a large cell-relative helicity—are favorable for producing miniature supercells. The mesocyclone, with its maximum intensity at 2 km above ground level (AGL), formed an hour before tornadogenesis. A tornado vortex signature (TVS) was identified between 1 and 3 km AGL, when the parent mesocyclone reached its peak radar-indicated intensity of 30 m s−1. The TVS was located between the updraft and forward-flank downdraft, near the center of the mesocyclone. Dual-Doppler wind analysis reveals that tilting of the low-level vorticity into the vertical direction and subsequent stretching by a strong updraft were the main contributors to the mesocyclone intensification.

Open access