https://phys.org/news/2018-09-nasa-satellite-hurricane-florence-eyewall.html

Infrared and Microwave Satellite Images Reveal

NOAA's National Hurricane Center (NHC) said that recent satellite imagery shows that the eye of Florence has become cloud filled. A microwave image of the storm at 12:41 a.m. EDT (0441 UTC) showed a double eyewall structure. These observations suggest that an eyewall replacement cycle is likely underway.