eye began to form, and the system attained hurricane status on August 31. It was classified as a Category 3 major hurricane 18 hours later. As it tracked north-northwestward, Hurricane Luis continued to strengthen, and became a Category 4 hurricane on the Saffir–Simpson scale on September 2. As it turned further westward, the cyclone maintained a rectilinear slow motion, and the intensity was confirmed by a reconnaissance flight on September 3. At the time of the flight, Luis was located approximately east of the Lesser Antilles. The storm began to accelerate slightly as it moved along a subtropical ridge, due to the absorption of Tropical Storm Karen by the stronger Iris. By the time that it approached the Lesser Antilles on September 4, Luis had sustained a wind field measuring from in diameter. On the morning of September 5, the islands of Dominica and Guadeloupe, which experienced hurricane-force winds on the northeastern coast of Grande-Terre and La Désirade, had been relatively spared by the storm. The eyewall of the hurricane, however, skimmed Antigua and directly passed over Barbuda as it slowly weakened. During this time, the storm proceeded slowly northwestward, causing moderate damage to Montserrat, Saint Kitts and Nevis, Sint Eustatius, and Saba. Later, Luis moved along St. Barthelemy, St. Martin, and ultimately crosed Anguilla, where the most powerful winds within the eyewall were estimated to have reached , and its central pressure had dropped from . Luis maintained its Category 4 intensity until September 7, when it was situated approximately north of Puerto Rico. After seven consecutive days as a major hurricane with maximum sustained winds of at least beginning on September 1, the storm gradually re-curved over the northern Atlantic as a Category 2 hurricane, its wind speed dropping to . On September 9, the center of the storm passed to the west of Bermuda, causing minor damage. Later that day, the storm began to accelerate as it traveled northeast, ahead of a strong trough located to the northwest of Luis. On the afternoon of September 10, Luis began to undergo an extratropical transition as it rapidly approached the Canadian coastline. Due to the rapid movement of the storm, significant weakening did not occur until Luis was at an unusually high latitude. The NHC reported that the central pressure of the storm decreased to , and sustained winds did not exceed . Luis maintained this intensity until September