Abstract Typhoon Lekima (2019) exhibited a long‐lived concentric eyewall (LLCE) structure, which was successfully simulated using the Weather Research and Forecasting model. The simulation captured the LLCE, including a nearly steady inner eyewall and an expanding outer eyewall indicated by the radius of the maximum tangential wind (RMW). The RMW budget diagnostics reveal that the radial advection of momentum is balanced by the vertical advection of momentum and diffusion at the inner RMW. This dynamic balance maintains a near‐zero radial gradient of tangential wind tendency, thereby supporting a steady inner eyewall with a sharpening tangential wind profile. The inward‐propagating rainbands enhance tangential winds outside the outer eyewall, maintaining a positive radial gradient of tangential wind tendency and facilitating the outer RMW expansion. These processes produce a wide moat, which prolongs the duration of the CE by weakening the suppression of the outer eyewall on the inner eyewall.
Observations from the Little Bunker
Last updated: August 18, 2025 04:13 PM
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