Hurricane Michael was the strongest storm of the 2018 Atlantic hurricane season. It became a hurricane at the western end of Cuba, moved northward and made landfall on the Florida Panhandle, then moved inland and turned northeastward, being downgraded to a tropical storm then an extratropical cyclone. 74 deaths in the United States and Central America were attributed to the storm and it caused an estimated US$25 billion in damage.
A better understanding of the structure and evolution of tropical cyclones is crucial for improving weather forecasts. Imagery from single‐Doppler Next Generation Weather Radar (NEXRAD) provided some important insights into this storm. Cha et al.  present observational evidence of changes in the shape of the eyewall of the hurricane while it was going through rapid intensification. It was seen to have an elliptical, triangular, and square shape at different times.
This is the first time that the evolution of eyewall asymmetries has been quantitatively deduced from observations and emphasizes the importance of coastal radar observations. A better understanding of this mechanism could potentially contribute to improving hurricane intensity forecasts in the future.
Citation: Cha, T.‐Y., Bell, M. M., Lee, W.‐C., & DesRosiers, A. J. . Polygonal eyewall asymmetries during the rapid intensification of Hurricane Michael (2018). Geophysical Research Letters, 47, e2020GL087919. https://doi.org/10.1029/2020GL087919
—Suzana Camargo, Editor, Geophysical Research Letters