High Quality Content by WIKIPEDIA articles! The effects of Hurricane Isabel in Pennsylvania were primarily related to tropical storm force winds across much of the state. Hurricane Isabel formed from a tropical wave on September 6, 2003 in the tropical Atlantic Ocean. It moved northwestward, and within an environment of light wind shear and warm waters it steadily strengthened to reach peak winds of 165 mph (265 km/h) on September 11. After fluctuating in intensity for four days, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina with winds of 105 mph (165 km/h) on September 18. It quickly weakened over land and became extratropical over western Pennsylvania the next day.