Hurricane Ivan

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.Hurricane Ivan prompts rogue wave rethink
'' The Register'', 5 August 2005 Their computer models also indicated that waves may have exceeded 130 feet (40 m) 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.

On September 20, Ivan's remnant surface low completed an anticyclonic loop and moved across the Florida peninsula. As it continued westward across the northern Gulf of Mexico, the system reorganized and again took on tropical characteristics on September 22. On September 22, the National Weather Service, "after considerable and sometimes animated in-house discussion egardingthe 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 weakened into a remnant low on September 24, as it moved overland into Texas. The remnant circulation of Ivan persisted for another day, before dissipating on September 25.

Records

Ivan set 18 new records for intensity at low latitudes. When Ivan initially became a Category 1 hurricane on September 3, it was centered 9.5 degrees north from the equator. This is farthest south position on record for a hurricane in the Atlantic basin. Later that day (6 p.m. UTC), when Ivan became a Category 3 hurricane, it was centered near 10.2 degrees north from the equator. This is the most southerly location on record for a major hurricane in the Atlantic basin. Just six hours later, Ivan also became the most southerly Category 4 hurricane on record in the Atlantic basin when it reached that intensity while located at 10.6 degrees north. Finally, at midnight (UTC) on September 9 while centered at 13.7 degrees north, Ivan became the most southerly Category 5 hurricane on record in the Atlantic basin. The latter record would not be surpassed until Hurricane Matthew in 2016, which reached Category 5 intensity at 13.4 degrees north.

Ivan had held the world record of 33 (with 32 consecutive) six-hour periods of intensity at or above Category 4 strength. This record was broken two years later by Pacific Hurricane/Typhoon Ioke, which had 36 (33 consecutive) six-hour periods at Category 4 strength. This contributed to Ivan's total Accumulated Cyclone Energy (ACE) of 70.38. The tornado outbreak associated with Ivan spawned 127 tornadoes, more than any other tropical cyclone worldwide.

Scientists from the Naval Research Laboratory at Stennis Space Center, Mississippi have used a computer model to predict that, at the height of the storm, the maximum wave height within Ivan's eyewall reached .

Preparations

Caribbean

By September 5, a hurricane watch was posted for Barbados. Early on the following day, a tropical storm watch was issued for Grenada. Later that day, hurricane watches were also put into effect for Saint Lucia, and Martinique. A tropical storm warning was issued for Saint Vincent and Grenadines and Tobago and Grenada. By 3 p.m. UTC on September 6, the hurricane watches and tropical storm watches and warnings were upgraded to a hurricane warning and expanded to: Barbados, Saint Vincent and Grenadines, Saint Lucia, Tobago, and Grenada. Simultaneously, a tropical storm warning was issued for Trinidad. On September 7, the hurricane warning in effect for several countries was downgraded to a tropical storm warning. By September, all tropical storm and hurricane watches and warnings were discontinued in the eastern portions of the Windward Islands.

As Ivan continued westward, a hurricane watch was issued for the ABC islands on September 8. Many schools and businesses were closed in the Netherlands Antilles, and about 300 people evacuated their homes on Curaçao.

In the Caribbean, 500,000 Jamaicans were told to evacuate from coastal areas, but only 5,000 were reported to have moved to shelters. 12,000 residents and tourists were evacuated from Isla Mujeres off the Yucatán Peninsula.

United States

In Louisiana, mandatory evacuations of vulnerable areas in Jefferson, Lafourche, Plaquemines, St. Charles, St. James, St. John the Baptist, and Tangipahoa parishes took place, with voluntary evacuations ordered in six other parishes. More than one-third of the population of Greater New Orleans evacuated voluntarily, including more than half of the residents of New Orleans