中文摘要：

Derechos 经常发生在欧洲和美国，而是在中国的 derechos 的报告是少见的。在这份报纸，雷达，卫星，和表面观察，数据被用来在 2011 年 4 月 17 日在华南分析一个 derecho 事件。对流系统与中等对流可得到的精力在环境形成了的生产 derecho mesoscale，大垂直的风砍，并且在中间的对流层的干燥的层，并且进行与前面和一根表面风集中线一起向南方。暴风能在雷达回响的特征和强风的原因根据差别被划分成二个阶段。一个阶段是一个 supercell 阶段，有塑造鞠躬的雷达回响的高降水的 supercell 的下沉后面的流入在导致了 Fujita F0 班强风。另外的阶段是一个 non-supercell 阶段(回响是顺序肾形的，塑造脚，并且一个平常的单个房间) ，在哪个 downbursts 在 Fujita F1 班上导致了强风。这个 derecho 事件有许多类似， derechos 在西方的国家观察了。例如，暴风对吝啬的流动垂直，强风位于鞠躬回响的鼓起的部分，并且 derecho 移动了与表面前面一起向南方。一些差别也被观察。摘要规模的强迫当进展不在时是弱的高振幅的 midlevel 马槽并且伴随强壮的表面气旋；然而，垂直的风砍是很强壮的，典型地代表与强壮的摘要规模的强迫联系的 derechos 的一个特征。对流可得到的势能以前被认为必要到弱强迫的原型和混合 derechos 的形成的对流可得到的势能和 downdraft 的极其高的价值；然而，这些价值多不到 2000 J 在这个 derecho 事件期间。

英文摘要：

Derechos occur frequently in Europe and the United States, but reports of derechos in China are scarce. In this paper, radar, satellite, and surface observation data are used to analyze a derecho event in South China on 17 April 2011. A derecho-producing mesoscale convective system formed in an environment with medium convective available energy~ strong vertical wind shear, and a dry layer in the middle troposphere, and progressed southward in tandem with a front and a surface wind convergence line. The windstorm can be divided into two stages according to differences in the characteristics of the radar echo and the causes of the gale. One stage was a supercell stage, in which the sinking rear inflow of a high-precipitation supercell with a bow-shaped radar echo induced a Fujita F0 class gale. The other stage was a non-supercell stage （the echo was sequentially kidney-shaped, foot-shaped, and an ordinary single cell）, in which downbursts induced a gale in Fujita F1 class. This derecho event had many similarities with derechos observed in western countries. For example, the windstorm was perpendicular to the mean flow, the gale was located in the bulging portion of the bow echo, and the derecho moved southward along with the surface front. Some differences were observed as well. The synoptic-scale forcing was weak in the absence of an advancing high-amplitude midlevel trough and an accompanying strong surface cyclone; however, the vertical wind shear was very strong, a characteristic typical of derechos associated with strong synoptic-scale forcing. Extremely high values of convective availa- ble potential energy and downdraft convective available potential energy have previously been considered necessary to the formation of weak-forcing archetype and hybrid derechos; however, these values were much less than 2000 J during this derecho event.