Meteorological history A tropical wave moved off the western coast of Africa on September 1. An area of low pressure associated with the wave moved slowly westward, and its convection initially appeared to become better organized. On September 3, as it passed to the south of the Cape Verde islands, organization within the system degraded, though convection increased the next day. The system gradually became better organized, and Dvorak classifications began early on September 5. Based on the development of a closed surface circulation, it is estimated the system developed into Tropical Depression Thirteen early on September 6. Hours later, it intensified into Tropical Storm Isabel, though operationally the National Hurricane Center did not begin issuing advisories until 13 hours after it first developed. Located within an area of light wind shear and warm waters, Isabel gradually organized as curved bands developed around a circular area of deep convection near the center. It steadily strengthened as it moved to the west-northwest, and Isabel strengthened to a hurricane on September 7 subsequent to the development of a large, yet ragged eye located near the deepest convection. The eye, overall convective pattern, and outflow steadily improved in organization, and deep convection quickly surrounded the -wide eye. Isabel intensified on September 8 to reach major hurricane status while located 1,300 miles (2,100 km) east-northeast of Barbuda. On September 9, Isabel reached an initial peak intensity of 130 mph (210 km/h) for around 24 hours, a minimal Category 4 hurricane on the Saffir–Simpson Hurricane Scale. Early on September 10, the eyewall became less defined, the convection near the eye became eroded, and northeasterly outflow became slightly restricted. As a result, Isabel weakened slightly to a Category 3 hurricane. The hurricane turned more to the west due to the influence of the Bermuda-Azores High. Later on September 10, Isabel restrengthened to a Category 4 hurricane after convection deepened near the increasingly organizing eyewall. The hurricane continued to intensify, and Isabel reached its peak intensity of 165 mph (270 km/h) and a minimum central pressure of 915 mbar (hPa; 27.02 inHg) on September 11, a Category 5 hurricane on the Saffir–Simpson Hurricane Scale. Due to an eyewall replacement cycle, Isabel weakened slightly, though it retained Category 5 status for 24 hours. As Isabel underwent another eyewall replacement cycle, outflow degraded in appearance and convection around the eye weakened, and early on September 13, Isabel weakened to