Abstract:Using observation data from Yantai S-band dual polarization Doppler weather radar, Rongcheng CINRAD/SA radar, radiosonde and surface meteorological stations, as well as the ERA5 (ECMWF reanalysis data) and the hail, and tornado information obtained from field surveys, this article analyzes a severe hailstorm and tornado that occurred on 1 October 2021 in the eastern part of Shandong Peninsula. The results are as follows. Compared to the climatic mean field, the 500 hPa northeast cold vortex responsible for this severe convective process was extremely strong, and at 850 hPa there was continuous southward water vapor transport from South China to the west of Northeast China. Under the abnormal circulation background, the atmospheric thermal and dynamic conditions, such as dry and cold in the upper troposphere, but wet and warm in the low troposphere, with strong 0-6 km 〖JP2〗vertical wind shear and convective available〖JP〗 potential energy (CAPE) on the eastern Shandong Peninsula, were very favorable for the occurrence of severe hailstorm and tornadoes. The features of pre-storm low pressure, thunderstorm high pressure, and cold pool were obvious near the surface. During the hail period, the supercell features were very typical, with distinct hook-shaped echo and inverted “V” anterior inflow gaps in the lower layers, and vertical profiles showed distinct bounded weak echo region (BWER) and differential reflectivity (ZDR) column characteristics. According to the large hail location and starttime information, the median values of reflectivity factor (ZH), ZDR and correlation coefficient (CC) were 48.7 dBz, 0.89 dB and 0.90 respectively. When tornado and severe hail appeared on the ground, the maximum storm-top 〖JP2〗divergent outflow reached 71.5 m·〖JP〗s-1. The cold pool airflow at the northern end of the rear flank gust front (RFGF) and the south inflow on the pre-storm side formed a strong vortex upward motion, resulting in an EF1-level tornado. The tornado occurred at the top of the hook-like echo, and large hailstones appeared on the north side of the inflow gap. About 5 min before the tornado, 〖JP2〗the radar detected the tornadic debris signature (TDS) features, with ZDR being as low as -0.1 dB〖JP〗 and CC as low as 0.81. About 11 min before the tornado genesis, the ZDR arc in the lower layer and the descending reflectivity core (DRC) in the rear flank side of the supercell was detected. Rongcheng and Yantai radars identified mesoscale cyclones and tornadic vortex signature (TVS) about 22 min and 5 min in advance, respectively. This can provide an important reference for tornado warning. Based on the observation analysis, the schematic diagram of the low-layer air flow field and the tornado and large hail-falling area of the supercell storm is summarized.