An eight-year climatology of the warm-season severe thunderstorm environments over North China

Abstract

Using proximity soundings taken during the warm seasons (May–September) of 2011–2018 over North China, this work investigated the environments of severe thunderstorms that caused the following four types of convective hazards: only hail (H), only thunderstorm high winds (W), only short-duration heavy rainfall (R), and two or three types of the above three hazards (hybrid). The environments for non-severe thunderstorms and no-rain days were also studied for comparison. Soundings in each weather category were further classified into mountain and plain groups. A set of parameters was tested for skill in discriminating between various categories. Results indicate that the environments over the plains, compared with those over the mountains, are generally characterized by stronger instability, more moisture, and higher vertical wind shear. Over both mountains and plains, the precipitable water (PW) shows the greatest skill overall in discriminating between various categories; the instability parameters show considerable skill in discriminating between the severe thunderstorm, non-severe thunderstorm, and no-rain categories but rather limited skill in discriminating between the four severe thunderstorm categories; the wind shear parameters show very limited skill in discriminating between various categories; the lifting condensation level (LCL) distinguishes well the environments of no-rain and R from those of other categories; and the mid-tropospheric pseudo-equivalent potential temperature is the only parameter investigated here that shows utility in discriminating between H and W environments. Probability distributions in two-parameter spaces reveal that great variations exist regarding the environments under which different weather types are most likely to occur.