Did you know that some tropical cyclones are designated “annular hurricanes” when they develop a distinctive structure with a large and nearly symmetrical eye, little or no discernable banding, and an eyewall entirely surrounded by intense thunderstorm activity? They are significantly stronger, maintain their peak intensities longer, and weaken more slowly than average hurricanes.
Also known as truck tire or doughnut hurricanes, they typically do not retain their annular structure for very long and soon revert to regular hurricane status. They are rare and develop more often in the Pacific than the Atlantic.
Read about Hurricane Iselle, a 2014 annular hurricane in the Central Pacific, in this AIR Currents article.