Downbursts in the Jianghuai region of East China are primarily caused by two storm types: isolated storms (ISs) and linear-embedded storms (LSs). However, systematic differences in their synoptic backgrounds, convective environments, and downburst formation mechanisms remain poorly understood, limiting the accuracy of downburst warnings. This study aims to quantify these differences and identify storm-type-specific triggering mechanisms for associated downbursts. Based on 18 downburst events (9 ISs and 9 LSs) from 2011 to 2024, we performed composite analysis using ERA5 reanalysis data (0.25°, hourly) and examined two representative downburst cases with S-band Doppler radar, automatic weather station (AWS; minute-resolution), and sounding data. Statistical significance of environmental differences was tested with t-tests. The results are as follows. (1) LSs form ahead of upper-level troughs near the 850-hPa front with strong synoptic forcing, whereas ISs develop along the subtropical high edge under weak forcing but with higher convective available potential energy (CAPE: ~3000 vs. ~2000 J kg⁻¹). LSs exhibit significantly stronger low-to-mid-level vertical wind shear (surface to 500 hPa: ~18 vs. ~7 m s⁻¹; 0–1 km: ~21 vs. ~6 m s⁻¹; p < 0.05). (2) For ISs, downburst initiation is dominated by negative buoyancy from hail melting and hydrometeor evaporation, driving a mid-level rear-inflow jet (RIJ) and a rapidly descending weak-echo gap. For LSs, a low-level RIJ, intensified by the surface cold pool and a developing mesocyclone (which generates a downward perturbation pressure gradient force), combines with hydrometeor drag to produce the downburst. (3) Surface observations show that ISs cause a larger pre-downburst temperature drop (mean 5.1 vs. 4.6°C in LSs) and a distinct dewpoint drop (3.7 vs. 1.0°C) within 10 min before the gust. In general, the two storm types develop under fundamentally different environmental controls (instability-dominated vs. shear-dominated) and rely on different primary mechanisms (thermodynamic cooling vs. dynamic forcing from RIJ and mesocyclone). These findings provide specific pre-downburst signatures (e.g., rapid temperature/dewpoint drops within 5–10 min ahead of peak winds) that can support storm-type-specific nowcasting of disastrous downbursts in the Jianghuai region of East China.

Based on multi-source observational data, the extreme convective gale caused by two different types of storms during a severe convective process in Huang-Huai region on 30 April 2021 is discussed. Results indicate that the severe convective process occurred under the background of the Northeast Cold Vortex with strong vertical wind shear and stratification instability. The initial convective activities were triggered by a surface cyclone and associated front and developed rapidly. The convective systems went through different evolution stages such as organization, movement, initiation and explosive development of isolated storm cells, and merge and reorganization in the subsequent 10 hours of propagation process, during which different characteristics of convective winds were caused by two different types of storms. Represented by Huai'an station, extreme convective winds (36.2 m/s) occurred in central Jiangsu due to the downburst caused by a strong supercell storm. An obvious hook echo structure occurred in the lower layer of the storm, corresponding to the deep mesocyclone with strong cyclonic rotation. As the extreme wind occurred, the mesocyclone stretched upward and downward simultaneously, accompanied by a horizontal rapid contraction process. The downdraft throughout the whole storm was located at the back of the hook structure of the storm, and the strong downdraft diverged outward rapidly near the ground, accompanied by a rapid drop of the strong reflectivity core in the storm. This resulted in extreme winds on small spatial-temporal scale and significantly discontinuous spatial distribution in Huai'an. Represented by Nantong area, the development of extreme winds in southeastern Jingsu involved interactions between multi-scale weather systems. An obvious gust front developed at the front of the linear convective system, resulting in large area of surface gales above Grade 10. The extreme gale in Tongzhou bay of Nantong (47.9 m/s) occurred at the back of the gust front, which was caused by the superposition effect of multi-scale systems, including the strong cold pool induced by the linear convective storm and the surface cold front, the rapid development of the surface cyclone that entered the sea and the downdraft in the rear of the storm with downward transfer of upper wind momentum.