The statistical data from the Hunan Provincial Lightning Protection Center showed that at 14:24 on February 5, lightning was detected in the southern part of Changsha city. By 17:12 on February 5, a total of 10 lightning strikes had been monitored across the province, located in Changsha and the eastern part of Yueyang.
However, at 14:32 on February 5, the first thunder of 2012 occurred just one day after the beginning of spring in the southern part of Changsha city. A staff member of the Hunan Meteorological Bureau described the scene at that time: "Two deafening claps of thunder followed by two flashes of lightning split off a layer of bark from top to bottom on the big tree in the courtyard of the Hunan Meteorological Warning Center."
Changsha, February 6 (reporter Li Huifang, correspondent Chen Jingjing) - On February 4, it was the start of spring according to the twenty-four solar terms. At 18:22 on that day, the official start of spring began, and at 14:32 on February 5, Changsha welcomed its first thunder after the spring season. The Hunan Meteorological Observatory reminded the public that as we enter the spring season, the alternation between cold and warm air masses from the north and south becomes more frequent, leading to more thunderstorms. Please enhance your awareness of prevention to avoid personal safety accidents and property losses caused by lightning. (A tree trunk in the courtyard of the Hunan Meteorological Warning Center was split from top to bottom by this year's first thunderstorm.)
In fact, around the time of the start of spring each year, there are usually thunderstorms in Hunan. This year, however, the first thunder in Changsha arrived earlier than usual and was localized. Experts from the Hunan Meteorological Bureau introduced that although February 4 marked the beginning of spring according to the twenty-four solar terms, due to Hunan still being enveloped by low temperatures and rainy weather, it hasn't yet entered the true sense of spring: "According to meteorological standards, when the average daily temperature exceeds 10°C for five consecutive days, it is considered officially entering spring."
Regarding the cause of this localized thunderstorm, Ye Chengzhi, the chief forecaster of the Hunan Meteorological Observatory, explained that starting from the evening of the 5th to the 7th, Hunan will be affected by a stronger cold air mass, resulting in a cooling and precipitation weather process. Before the influence of the cold air, the southwest warm and humid airflow strengthened somewhat, and the surface trough also developed somewhat, causing the surface temperature to rise to a certain extent. The unstable energy stored in the atmosphere increased, making it easier to trigger localized strong convective weather. In addition, according to the ground meteorological element monitoring at 14:00 on February 5, there was a small-scale surface convergence line between Changsha and Zhuzhou. Near the surface convergence line is usually where strong convective weather occurs.