After reaching tropical storm status, the maximum sustained winds existed for three days between 40 mph (65 km/h) and 50 mph (85 km/h). This is because of the large size of Florence; the wind field reached 460 miles (745 km) wide with a radius of maximum winds of about 110 miles (170 km). By September 6, an orgained form of cloud swirls became visible, with thin rainbands developing in the southeast and northwest quadrants. As a result, hurricane forecasters predicted Florence to quickly develop and reach major hurricane status. Though convection slowly moved closer to the center of the storm, forecasters could not detect an organized center of circulation late on September 13.