Hurricane Ivan - Meteorological History

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, 1,150 miles (1,850 km) to the east of Tobago. Later that day, the storm intensified rapidly, and by 5 pm EDT (2100 UTC), Ivan became a Category 3 hurricane with winds of 125 miles per hour (200 km/h). 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 160 mph (260 km/h). 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 Jamaica, 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 winds of 165 mph (270 km/h) as it passed within 30 miles (50 km) of Grand Cayman. Ivan reached its peak strength with a minimum central pressure of 910 millibars (27 inHg) on September 12, making Ivan the tenth most intense Atlantic hurricane on record, as of August 2007. 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, it weakened slightly to Category 4 strength, which it maintained while approaching the Gulf Coast of the United States.

Just before it made landfall in the United States, Ivan's eyewall weakened considerably, and its southwestern portion almost disappeared. Around 2 am CDT September 16 (0700 UTC), Ivan made landfall on the U.S. mainland in Gulf Shores, Alabama as a Category 3 hurricane with 120 mph (195 km/h) winds; some hurricane information sources put the winds from Hurricane Ivan near 130 mph (210 km/h) 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 the same day, still over Alabama. Ivan lost tropical characteristics on September 18 while crossing Virginia. Later that day, the remnant low 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.

On September 20, Ivan's remnant surface low completed an anticyclonic loop and moved across the Florida peninsula. As it continued west across the northern Gulf of Mexico, the system reorganized and again took on tropical characteristics. On September 22 the National Weather Service, "after considerable and sometimes animated in-house discussion the demise of Ivan," determined that the low was in fact a result of the remnants of Ivan and thus named it accordingly. On the evening of September 23, the revived Ivan made landfall near Cameron, Louisiana as a tropical depression. Ivan finally dissipated on September 24 as it moved overland into Texas.