Single Doppler radar observation of the concentric eyewall in Typhoon Saomai, 2006, near landfall

Landfalling Typhoon Saomai (2006) was observed by the CINRAD WSR‐98D radar on the southeast coast of China. This study documents the formation and evolution of a concentric eyewall episode using the axisymmetric circulation derived from the ground‐based velocity track display technique. Saomai's outer eyewall formed after reaching its peak intensity, ∼5 hours before landfall. Updraft, tangential wind maximum and shallow low‐level inflow coincided with the high reflectivity and voriticity ring in both inner and outer eyewalls, surrounding a moat region characterized by weak downward motion and lower reflectivity. The subsidence and rain‐free moat region between the two eyewalls was filled with rain and upward motion prior to landfall, indicating a breakdown in the outer eyewall which was a barrier to radial inflow. Meanwhile, the outer vorticity maximum flattened and the central pressure dropped 9 hPa. The eyewall replacement cycle didn't complete probably due to the landfall.