sentences:  Using the Dvorak technique, a method used to estimate the intensity of tropical cyclones, a value of 7.6 was obtained.This indicated that maximum winds at the surface could have been as high as 181 mph (291 km/h); however, this was not used as the reported intensity as six- to twelve-hour averages indicated sustained winds around 160 mph (260 km/h).After maintaining this intensity for roughly 18 hours, the system began to weaken as it moved into a less favorable environment with moderate wind shear.