On the Fine-scale Boundary-layer Dynamic Processes Leading to Extreme Gust Wind Events in East China: Insights Gained From Radar Wind Profiler Mesonet Observations

Extreme wind gusts pose significant threats to human safety and infrastructure, yet limited pre-onset observational constraints lead to substantial uncertainties in nowcasting and forecasting. In this study, we investigate two severe wind events: a dry extreme surface gust event (wind speed > 35 m s⁻¹) that occurred in Beijing on 30 May 2024, and a wet convective severe wind event in coastal East China on 30 April 2021. Their dynamical characteristics are examined using a high-density radar wind profiler mesonet, a meteorological tower, automated weather stations, and radar and satellite observations. For the Beijing event, multi-source observations show that a multicellular storm developed ahead of a convergence line formed by the collision between northeasterly cold outflows and environmental southerlies during downhill propagation. Evaporative cooling initiated strong downdrafts, which were further intensified by downward momentum transport and pressure gradient forcing. After reaching the plain, two convective segments merged into a well-organized squall system containing a midlevel mesovortex and an intense rear-inflow jet. Low-level frontogenesis and shearing deformation sustained mesoscale convection and enhanced small-scale turbulent processes. Turbulent inverse energy cascades intensified markedly as wind speeds increased. In the coastal event, cloud clusters developed ahead of a baroclinic midlevel trough and organized into a comma-shaped squall system that moved offshore. A mesovortex embedded within the stratiform region generated strong northerly rear inflows that descended to the surface, producing damaging gusts. These cases highlight the distinct but complementary roles of multiscale dynamical processes in accelerating surface winds to extreme intensity. These findings demonstrates the value of radar wind profiler mesonet observations for resolving multiscale convective dynamics and provides important observational support for improving numerical weather prediction of extreme gust events.