Distinct Mechanisms of Damaging Gusts at Different Locations of a Bow Echo Embedded in a Squall Line

Damaging gusts near bow echoes are among the most destructive convective hazards, yet accurately forecasting their location and intensity remains highly challenging because the main physical processes across different storm regions are poorly understood. Using a dense network of seven S-band and three X-band polarimetric radars, together with a hydrometeor identification algorithm and three-dimensional wind retrievals, this study investigates the distinct mechanisms of damaging gusts at different locations of a bow echo embedded in a squall line over the Yangtze–Huaihe region. The results indicate that the squall line is induced by sub-synoptic-scale dynamic forcing under the influence of the Northeast China cold vortex, and sustained by the strong low-level convergence and associated upward motion. During its mature stage, a pronounced bow echo became embedded within the central segment of the squall line. Near the bow echo center, where a damaging gust of 37.6 m s⁻¹ is observed, a strong descending rear-inflow jet appears to generate downdrafts through mid-level radial convergence and evaporative cooling of hydrometeors, and the drag effect of large raindrops likely contribute to the destructive surface gust. At the leading edge of the bow echo, where a gust of 30 m s⁻¹ occurs, the downdrafts together with the horizontal pressure gradient force associated with an intense cold pool are linked to the extreme northwesterly gust. By contrast, the extreme southeasterly gust of 29.9 m s⁻¹ observed at the outflow boundary appears to be related to a low-level meso-γ-scale vortex coupled with strengthening environmental wind. Finally, a physical-mechanism-based and location-dependent conceptual model is proposed, which can help improve the early warning of damaging gusts associated with bow echoes in operational weather forecasting.