Hurricane Ivan was a large, long-lived, Cape Verde hurricane that caused widespread damage in the Caribbean and United States. The cyclone was the ninth named storm, the sixth hurricane and the fourth major hurricane of the active 2004 Atlantic hurricane season.
Ivan formed in early September, and reached Category 5 strength on the Saffir–Simpson Hurricane Scale (SSHS). Ivan caused catastrophic damage in Grenada as a strong Category 3 storm, heavy damage in Jamaica as a strong Category 4 storm, and then severe damage in Grand Cayman, Cayman Islands, and the western tip of Cuba as a Category 5 hurricane. After peaking in strength, the hurricane moved north-northwest across the Gulf of Mexico to strike Pensacola/Milton, Florida and Alabama as a strong Category 3 storm, causing significant damage. Ivan dropped heavy rain on the Southeastern United States as it progressed northeastward and eastward through the Eastern United States, becoming an extratropical cyclone on September 18. The remnant low of the storm moved into the western subtropical Atlantic and regenerated into a tropical cyclone on September 22, which then moved across Florida and the Gulf of Mexico, and then into Louisiana and Texas, causing minimal damage. Ivan degenerated into a remnant low on September 24, before dissipating on the next day.
Ivan caused an estimated US$26.1 billion (equivalent to $ billion in ) in damage along its path, of which $20.5 billion occurred in the United States.
Meteorological history
On September 2, 2004, Tropical Depression Nine formed from a large tropical wave southwest of Cape Verde. As the system moved to the west, it strengthened gradually, becoming Tropical Storm Ivan on September 3, and reaching hurricane strength on September 5, to the east of Tobago. Later that day, the storm intensified rapidly, and by 5 p.m. EDT (UTC–4), Ivan became a Category 4 hurricane with winds of . The National Hurricane Center said that the rapid strengthening of Ivan on September 5 was unprecedented at such a low latitude in the Atlantic basin.
As it moved west, Ivan weakened slightly because of wind shear in the area. The storm passed over Grenada on September 7, battering several of the Windward Islands. As it entered the Caribbean Sea, Ivan reintensified rapidly and became a Category 5 hurricane, just north of the Windward Netherlands Antilles (Curaçao and Bonaire) and Aruba on September 9, with winds reaching . Ivan weakened slightly as it moved west-northwest towards Jamaica. As Ivan approached the island late on September 10, it began a westward jog that kept the eye and the strongest winds to the south and west. However, because of its proximity to the Jamaican coast, the island was battered with hurricane-force winds for hours.
After passing Cuba, Ivan resumed a more northerly track and regained Category 5 strength. Ivan's strength continued to fluctuate as it moved west on September 11, and the storm attained its highest 1-minute maximum sustained winds of as it passed within of Grand Cayman. Ivan reached its peak strength with a minimum central pressure of on September 12. Ivan passed through the Yucatán Channel late on September 13, while its eyewall affected the westernmost tip of Cuba. Once over the Gulf of Mexico, Ivan weakened slightly to Category 4 strength, which it maintained while approaching the Gulf Coast of the United States. When Ivan entered the Gulf of Mexico, U.S. Naval Research Laboratory ocean-floor pressure sensors detected a freak wave, which was caused by the hurricane. The wave was around high from peak to trough, and around long. Their computer models also indicated that waves may have exceeded in the eyewall.
Just before it made landfall in the United States, Ivan's eyewall weakened considerably, and its southwestern portion almost disappeared. Around 2 a.m. CDT (UTC–5) on September 16, Ivan made landfall on the U.S. mainland in Gulf Shores, Alabama, as a Category 3 hurricane, with 1-minute sustained winds of . Some hurricane information sources put the winds from Hurricane Ivan near (Category 4) upon landfall in Alabama and northwestern Florida. Ivan then continued inland, maintaining hurricane strength until it was over central Alabama. Ivan weakened rapidly that evening and became a tropical depression on the same day, still over Alabama. Ivan lost tropical characteristics on September 18 while crossing Virginia, becoming an extratropical storm. Later that day, the remnant low of Ivan drifted off the U.S. mid-Atlantic coast into the Atlantic Ocean, and the low-pressure disturbance continued to dump rain on the United States.