Ivan became a tropical depression on September 2, 2004 and was christened the following day while it was far out in the eastern Atlantic. Ivan was upgraded to hurricane on September 5th and began to deepened rapidly. The central pressure dropped 39 millibars in 24 hours and was packing top winds of 130 by that evening. It then became the southernmost major hurricane on record. As rapidly as it had strengthened, Ivan weakened as dry air was entrained into the inner circulation. Shaking of the effects of the dry air, Ivan intensified as it approached the islands. The eyewall passed directly over the island of Grenada as a strong category three hurricane. Damage was severe. In the Caribbean, Ivan began another rapid deepening phase, peaking at 165 mph on the evening of September 8th as it moved slowly towards Jamaica. It was the first of three occasions when Ivan would attain Category Five status.
Prayers were fervent on the vulnerable island nation as Ivan approached. Jamaicans breathed a sigh of relief as the devastating hurricane turned directly west at the last minute and weakened slightly during a fortuitous eyewall replacement cycle, keeping the highest winds of the eyewall just south of the island. The Caymans would not be so lucky. In a low shear environment, Ivan again attained Category Five status around noon on September 11th. This stint as a Cat Five was short lived as Ivan steamed toward the Caymans. But the hurricane scored a direct hit on Grand Cayman with high Category Four winds and a devastating storm surge that nearly inundated the entire island. Ivan regained Cat Five intensity west of the Caymans on September 12th. The very warm waters of the Northwest Caribbean and a low shear environment allowed Ivan to stay a Cat Five for a record thirty hours.
Ivan passed through the Yucatan Channel and into the southeastern Gulf of Mexico early on September 14th. Ivan was turning north northwestward, exploiting a weakness in the upper ridge ahead of an approaching trough. As Ivan steamed northward, the trough began to produce shear that weakened the hurricane slowly. Cooler water and dry air also were working against the large and powerful hurricane, but its massive size allowed it to stay stronger than a smaller hurricane might have.
A massive evacuation occurred on the 15th as Ivan set its sights on the northern Gulf Coast. There was great concern that Ivan might be the big one for the Big Easy, but New Orleans dodged a bullet as the hurricane closed in on the Alabama coast, making landfall near Gulf Shores around 1:50 a.m. CDT early on the 16th with top winds of 120 mph. Twenty five U.S. fatalities were reported.
