Climatology and pre-convection environmental conditions of dry and wet thunderstorm high winds over eastern China

Thunderstorm high wind (THW) is defined as a kind of convective weather phenomenon with a maximum wind gust speed not less than 17.2 m·s⁻¹ over China. It is a sudden, damaging, but common convective weather phenomenon during the warm seasons of China. By adopting a kernel density estimation (KDE) for the THWs during warm seasons (March–September) of 2010–2019 over eastern China and the European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5) dataset, the dry and wet THWs usually with different mechanisms are objectively obtained, and climatology and pre-convection environmental conditions investigated. KDE shows the total precipitable water (TPW) of 38 mm can be used as the threshold for distinguishing dry THWs from wet ones. Dry THWs mainly concentrate in North China and Yunnan province, while wet ones mainly concentrate in South China. West of Hebei province has high frequencies for both dry and wet THWs. A comparison of pre-convection environmental conditions shows dry THWs mainly occur under environmental conditions with lower saturation at both the middle-lower and upper layers, while wet ones usually have relatively lower saturation at the middle-lower layers. The instability of wet THWs can be well characterized by the most unstable lifted index (MULI) and most unstable convective available potential energy (MUCAPE), while dry ones can be well depicted by the lower 500 hPa temperature caused higher temperature difference (DT85) or temperature lapse rate (TLR85) between 850 and 500 hPa. The 0–6-km vertical wind shear (SHR₆) can distinguish dry THWs from wet ones better than SHR₁. The typical difference can be comprehensively revealed by the representative soundings. The results provide objective references for understanding and forecasting THWs under dry and wet environmental conditions.