An observational study of a circular gust front over the Yangtze Delta, China

Abstract Concentric gust fronts are formed when a thunderstorm’s downdraft reaches the ground and the outflow from the cold pool spreads uniformly outwards into the surrounding warm and humid air mass. Observational evidence presented here show the case of narrow‐band echoes forming a ring around a thunderstorm. Unlike conventional gust fronts, concentric or circular gust fronts are more likely to form in subtropical high‐pressure environments, where the horizontal wind speed in the middle to lower troposphere is relatively weak, the underlying surface is uniform and the temperature gradient around the cold pool that produces the circular gust front remains largely consistent.