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Hurricane Irma

Category 5 Atlantic hurricane in 2017

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On September 6, 2017, at 12:30 UTC (8:30 AM Antigua and Barbuda Local Time), the Advanced Baseline Imager (ABI) instrument aboard NOAA's preliminary GOES 16 satellite captured a true-color image of Hu
NOAA's GOES 16 Satellite · Public domain

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Through Atmospheric pressure and Cuba

The ninth named storm, fourth hurricane, second major hurricane, and first Category 5 hurricane of the extremely active 2017 Atlantic hurricane season, Irma developed from a tropical wave near the Cape Verde Islands on August 30. Favorable conditions allowed Irma to rapidly intensify into a Category 3 hurricane on the Saffir–Simpson wind scale by late on August 31. The storm's intensity fluctuated between Categories 2 and 3 for the next several days, due to a series of eyewall replacement cycles. On September 4, Irma resumed intensifying, becoming a Category 5 hurricane early the next day. Early on September 6, Irma peaked with 1-minute sustained winds of 180 mph (290 km/h) and a minimum pressure of 914 hPa (27.0 inHg). Irma was the second-most intense tropical cyclone worldwide in 2017 in terms of barometric pressure, and the strongest worldwide in 2017 in terms of wind speed. Another eyewall replacement cycle caused Irma to weaken back to a Category 4 hurricane, but the storm re-attained Category 5 status before making landfall in Cuba. Although Irma briefly weakened to a Category 2 storm while making landfall on Cuba, the system re-intensified to Category 4 status as it crossed the warm waters of the Straits of Florida, before making landfall on Cudjoe Key on September 10. Irma then weakened to Category 3 status, prior to another landfall in Florida on Marco Island later that day. The system degraded into a remnant low over Alabama and ultimately dissipated on September 13 over Missouri.

Irma caused widespread and catastrophic damage throughout its long lifetime, particularly in the northeastern Caribbean and the Florida Keys. It was also the most intense hurricane to strike the continental United States since Katrina in 2005, the first major hurricane to make landfall in Florida since Wilma in the same year, and the first Category 4 hurricane to strike the state since Charley in 2004. The storm caused catastrophic damage in Barbuda, Saint Barthélemy, Saint Martin, Anguilla, and the Virgin Islands as a Category 5 hurricane. The hurricane caused at least 134 deaths: one in Anguilla; one in Barbados; three in Barbuda; four in the British Virgin Islands; 10 in Cuba; 11 in the French West Indies; one in Haiti; three in Puerto Rico; four on the Dutch side of Sint Maarten; 92 in the contiguous United States, and four in the U.S. Virgin Islands. The word Irmageddon was coined soon after the hurricane to describe the damage caused by the hurricane. Hurricane Irma was the top Google searched term in the U.S. and globally in 2017.

Meteorological history

A tropical wave left the west coast of Africa on August 27, producing a large area of deep convection. Over the following days, convection became more concentrated over the northern part of the disturbance, and a surface circulation developed by August 30. The National Hurricane Center (NHC) estimates that the disturbance developed into a tropical depression around 00:00 UTC August 30, about 120 nautical miles (138.1 miles; 222.2 kilometers) southwest of the Cape Verde Islands. Six hours later, the depression intensified into Tropical Storm Irma, the ninth named storm of the 2017 Atlantic hurricane season. Located over warm sea surface temperatures (SSTs), and within an environment of low wind shear, Irma underwent rapid intensification. The formation of an eye around 06:00 UTC on August 31 signified Irma's strengthening into a hurricane, just 30 hours after formation. Turning to the northwest as the ridge steering the cyclone weakened, Irma rapidly intensified into a major hurricane by 00:00 UTC September 1. Within a 48-hour period, the hurricane's intensity had increased by 80 mph (130 km/h). Fluctuations in intensity occurred over the next few days due to internal processes, as the first aircraft reconnaissance mission into Irma discovered an eye 29 mi (47 km) in diameter and surface winds of 115 mph (185 km/h) on September 3.

As Irma continued approaching the Leeward Islands, the hurricane underwent a second and more robust period of rapid intensification on September 4, becoming a Category 5 hurricane early the following day. The extremely powerful hurricane continued to strengthen, with maximum sustained winds peaking at 180 mph (290 km/h) shortly afterwards. Irma acquired annular characteristics around this time, with the storm exhibiting a large, symmetric central dense overcast (CDO). At 05:45 UTC on September 6, Irma made landfall along the northern coast of Barbuda at peak intensity, with the storm's central minimum pressure having bottomed out at 914 mbar (27.0 inHg)—this was the lowest minimum pressure in the Atlantic since Dean in 2007; the storm also made landfall with maximum sustained winds of 180 mph (290 km/h). Irma continued to maintain its peak intensity until 12:00 UTC on September 6 and made additional successive landfalls on that same day, at 11:15 UTC on Sint Maarten, and at 16:30 UTC on Virgin Gorda, in the British Virgin Islands.

Irma maintained Category 5 strength for several days as it passed north of the Greater Antilles. After beginning an eyewall replacement cycle, Irma weakened to a Category 4 hurricane as it passed south of the Turks and Caicos Islands early on September 8, subsequently ending the 60-hour continuous period of Irma maintaining Category 5 intensity, the second-longest any Atlantic storm had maintained winds above 156 mph (251 km/h)—behind only the 1932 Cuba hurricane. The hurricane then began tracking more to the west due to the intensification of a subtropical ridge to its north. Once the eyewall replacement cycle was complete, Irma began to re-intensify, and it attained Category 5 intensity for the second time at 18:00 UTC that day east of Cuba. The very powerful hurricane then made landfall in Cayo Romano, Cuba, at 03:00 UTC on September 9, with winds of 165 mph (266 km/h). This made Irma only the second Category 5 hurricane to strike Cuba in recorded history, after the 1924 Cuba hurricane. As the eye of Irma moved along the northern coast of Cuba, quick weakening ensued due to extended land interaction, with the eye becoming cloud-filled. Irma bottomed out as a high-end Category 2 storm later on September 9.

After slowing down late that day, the hurricane turned northwestward towards Florida. This motion resulted from Irma rounding the southwestern edge of the subtropical high to its northeast and a low-pressure system that was located over the continental United States, to its northwest. Moving over the warm waters of the Straits of Florida, Irma quickly re-intensified to a Category 4 hurricane at 06:00 UTC on September 10, as deep convection improved and the eye became better defined. The cyclone made landfall in Cudjoe Key, Florida, at 13:00 UTC on September 10, at Category 4 intensity, with winds of 130 mph (210 km/h). Increasing wind shear and land interaction caused the satellite appearance of the storm to become ragged later that day, and Irma weakened to Category 3 intensity before making its seventh and final landfall at 19:30 UTC, in Marco Island, Florida, with sustained winds of 115 mph (185 km/h). Once Irma had moved inland, it began to accelerate to the north-northwest, while rapid weakening began to occur due to the increasing wind shear, land interaction, and dry air, with the storm falling below Category 3 intensity hours after landfall. Irma finally weakened to a tropical storm on September 11 as it entered southern Georgia. The greatly weakened storm turned more northwestward and degenerated to a remnant low as it crossed into Alabama by 06:00 UTC September 12. The remnant low continued to diminish in strength as it progressed northwestward, dissipating over Missouri the following day.

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