Polygonal eyewalls in a 2 km WRF simulation of Wilma (2005)

A 2 km WRF simulation was run with GFS initial conditions. During an 18 hour period, the eyewall appeared as triangles, squares, and pentagons. The shapes showed some consistency with vortex Rossby wave theory. The impact of the shapes on eyewall convection and eye/eyewall mixing was investigated. Eliassen-Palm flux diagnostics showed the vortex Rossby waves associated with the shapes had a generally negative effect on the mean flow. Empirical normal mode analysis was used to isolate the dominant vortex Rossby wave modes. A nondivergent barotropic model was initialized with snapshots of model state to gauge the extent to which dry dynamics dominate the shape selection process.