ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 47 Issue 2 > 2021,47(2):216-229. DOI:10.7519/j.issn.1000-0526.2021.02.008 Prev Next
Analysis of the 13 April 2019 Strong Tornado in Xuwen County, Guangdong Province
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Abstract:
An EF3 strong tornado in Xuwen County of Zhanjiang City, Guangdong Province on 13 April 2019 was analyzed by using observation data, automatic weather station data, Zhanjiang Doppler Radar data and FY4A satellite high resolution visible cloud images. The results show that this strong tornado occurred near the coastal zone in the low latitude area, with a path length of about 16 km. It experienced a complex process of “three times on 〖JP2〗land and two times on sea”, lasting for about 36 minutes. The 〖JP〗mesoscale convective system producing tornado supercell appeared in front of the warm and low pressure trough, where the southwest air flow and southerly jet flow converged significantly in the middle and lower layers. The environmental conditions were characterized by strong vertical wind shear, low lifting condensation height, large storm relative helicity and large energy helicity. There were mesoscale convergence lines and smallscale vortex triggering convection on the ground. The tornado 〖JP2〗passed through the〖JP〗 automatic weather station of Hean Town Government of Xuwen County, which was affected by different parts of the tornado vortex. The wind direction of the tornado changed from clockwise to reverse to clockwise, and the wind force got to Grade 15. The average pressure and temperature dropped sharply by 2.6 hPa·（5 min）-1 min and 1.7 ℃·（5 min）-1, respectively. The tornado occurred in a supercell storm with positive cloudtoground lightning and high cell centroid. The hook echo and echo pendency were obviously accompanied by lowlevel strong mesocyclone and tornado vortex signature. The intensity and top height of the mesocyclone changed in inverse phases, and the three (two) peak value (valley value) of the intensity and three (two) valley value (peak value) of top height exactly corresponded to the time of the three (two) land (sea) activities of the tornado. When the tornado was on the land (sea), the mesocyclone was stronger (weaker) and the top height was lower (higher). The tornado occurred near the top of the hook echo and at the maximum 〖JP2〗TBB gradient on the windward side of mesoβ scale convective system, under the water vapor plume and during the period when the height of the bottom of the mesocyclone was lower than 500 m.
Keywords:
strong tornado, environmental condition, supercell, mesocyclone, Xuwen
Clc Number:
P445，P458
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