Wednesday, 5 November 2014
Capitol Ballroom AB (Madison Concourse Hotel)
A tornado generated at about 2300 UTC in 16 April 2013 in Chaoyang village, Qixing block, Guilin, China accompanied by the downburst and gale. The rainfall in Chaoyang between 2300UTC 16 to 0000 UTC 17 April 2013 was 52mm, and the temperature dropped 1.5 °C in one hour. The affected area of tornado was only 10km away from Guilin radar station. A 17m/s outflow could be seen in the radar radial velocity image at 2300 UTC 16 April, but the inflow was weak. This was the evidence for the existence of tornado. The couplet of positive and negative velocity indicated that mesoscale cyclone existed. The VIL was not high, only 27 kg.m-2. The outflow area was more to the east on 9.9 ° radar elevation than 2.4 ° radar elevation. It meant that the tornado was declining. From the radar radial velocity profile, it could be found that there was convergence in the lowest 3km and divergence on 6km. The structure was also declining. The outflow in low level was 20m/s. The tornado could be confirmed by these features. The radar reflectivity profile showed that the strongest reflectivity was 3-5km high, there might be downburst. In the images of Liuzhou radar, the radial velocity reached 27m/s, the VIL reached 43kg.m-2, the echo top reached 1.1-12.2km. The reflectivity profile showed that in the initial stage of tornado the reflectivity present a hook, the strongest reflectivity was at about 6km. The hook echo became atypical when the gale strengthened on the surface. The reflectivity strengthened and descended, similar to the downburst.. A flash flood case occurred in Longhu village from 1500 UTC to 2600 UTC 15 May 2013. The precipitation was 293mm in 3 hours in Longhu village Cuilin. A short-time heavy rain also occurred in Yongan village Guilin from 1800 to 2100 UTC 21 May 2014, one hour precipitation reached 95mm. The radar reflectivity in two cases was 53-58dBz. The adverse wind region existed at the raining area. But the VIL and reflectivity were not as strong as the supercell in tornado case, the echo height were only 6km.
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