The eye is so big that anything underneath it would experience 7 to 8 hours of calm, before getting slammed by the storm’s eyewall. “It wouldn’t surprise me if some birds are taking shelter there,” Klotzbach said.
John Knaff, a tropical cyclone researcher also out of Colorado State, estimated Champi’s eye is about 1.5 standard deviations bigger than average or roughly in the top 10 percent.
While Champi’s eye is big, Klotzbach said it’s not unheard of for storms in the northwest Pacific to form giant eyes.
The unmistakable and menacing eye is a textbook characteristic of what are known as annular tropical cyclones (typhoons or hurricanes).
In addition to their large eyes, annular storms typically contain a concentrated core of thunderstorms around the eye which abruptly cutoff leaving a lack of spiral banding along their periphery. Just four percent of hurricanes and typhoons are annular, and they are known for their staying power, weakening more slowly under unfavorable conditions compared to conventional storms.
Some people call them “doughnut” hurricanes or typhoons due to their shape.
Before morphing into an annular storm, Champi peaked in intensity as a super typhoon on Sunday, with maximum sustained winds of 150 mph, equivalent to a category 4 hurricane. On Wednesday, it swept by Iwo Jima producing wind gusts to at least 68 mph.