html On the morning of July 3, judging from the Fengyun-4 high-definition visible light satellite cloud image, although the situation of two typhoons dancing together in the Western Pacific continues today, the situation is very different from before - Typhoon Siamba that landed in South China has already It has weakened significantly due to the friction of inland terrain. Although the obvious spiral structure of Typhoon Siam can still be seen in the satellite cloud map today, the core convection area is becoming withered and shriveled. At the same time, Typhoon Avery also quietly passed over the Ryukyu Islands and entered the East China Sea. However, under the influence of vertical wind shear and other unfavorable factors, the convective clouds of Typhoon Avery were completely cut away, leaving only a dry low-level circulation center. .
Although Typhoon Siam has made landfall, its intensity is weakening significantly. At 11 a.m. this morning, the center was located in Guangxi and it weakened to a level 8 tropical storm . However, from the radar map, the convection in the core area of Typhoon Siam has weakened. At the same time, the convection on its south side is still very active, pulling up a large number of vigorous rainbands along the southern coast of Guangxi and many places in Guangdong. The rainbands in some areas also appear dark red, which means that local convective activities are quite strong.
At 23:50 on the evening of July 2nd, Beijing time, the Foshan Meteorological Observatory raised a tornado warning, pointing out that there may be tornadoes in Dali, Shishan, Lishui, Nanhai District, Yundonghai, Leping and other towns and streets in Sanshui District. volume, reminding the local area to organize defense immediately. As of this morning, the Foshan Meteorological Observatory has been continuously raising tornado warnings and has issued 6 tornado warnings. In addition to Foshan , Guangzhou Huadu and other places also issued tornado warnings this morning. It can be seen that the weather in Guangdong today is still very unstable.
In the past July 2, multiple tornadoes occurred in Guangdong, respectively in Chaoan, Shantou, and Nanhai, Foshan., such as Xiqiao Town, Nanhai, Foshan. Powerful tornadoes connected the sky and the earth, directly passing through densely populated areas. area, causing a relatively large impact.
Whether it was several tornadoes on July 2 or a large number of tornado warnings today, they are all related to Typhoon Siam. You can also see from the cloud map that Typhoon Siam is in the west of South China, while tornadoes all occur on the right side of the typhoon. This is where the airflows from the southeast and southwest fight, so the typhoon lands in western Guangdong, the Pearl River Delta and Guangdong. East is prone to tornadoes, this is a rule.
Although typhoons and tornadoes are two different weather phenomena, tornadoes may indeed be induced during typhoon activities: tornadoes can also appear in landfalling typhoons, and some can parasitize within the main circulation of typhoons, and to the right front of landfalling typhoons. Quadrant and are high-incidence areas for tornadoes. According to research, tornado belts often appear in areas with strong low-altitude vertical shear, strong convection, strong amplitude convergence, and strong vertical motion. When a typhoon approaches land or lands, low-altitude wind shear is caused by surface wind friction. The vertical wind shear decreases and the vertical wind shear increases, and the coastal mountain range terrain can also enhance amplitude convergence, so tornadoes often occur in landfalling typhoons. For example, the super typhoon Rainbow that landed on the coast of South my country in October 2015. Before and after it landed in Zhanjiang , tornado outbreaks occurred in the Pearl River Delta and eastern Guangdong. A powerful EF3 tornado hit Foshan. The maximum wind force was estimated to be above level 17, causing a major blackout in the Pearl River Delta.
Of course, the storms caused by the remnant circulation of Typhoon Siam continue to affect South China. For example, from yesterday to today, the cumulative rainfall in Leizhou, Guangdong in 24 hours has exceeded 250 millimeters, reaching the level of heavy rainstorms. As the impact of Typhoon Siam continues, Guangxi and Guangdong must continue to be vigilant!
