Hurricane Ida

Hurricane Ida was a deadly and extremely destructive tropical cyclone that became the second-most damaging and intense hurricane to make landfall in the U.S. state of Louisiana on record, behind Hurricane Katrina in 2005. In terms of maximum sustained winds at landfall (150 mph or 240 km/h), Ida tied with 2020's Hurricane Laura and the 1856 Last Island hurricane as the strongest on record to hit Louisiana. The remnants of the storm also caused a tornado outbreak and catastrophic flooding across the Northeastern United States. The ninth named storm, fourth hurricane, and second major hurricane of the 2021 Atlantic hurricane season, Ida originated from a tropical wave in the Caribbean Sea on August 23. On August 26, the wave developed into a tropical depression, which organized further and became Tropical Storm Ida later that day, near Grand Cayman. Amid favorable conditions, Ida intensified into a hurricane on August 27, just before moving over western Cuba. A day later, the hurricane underwent rapid intensification over the Gulf of Mexico, and reached its peak intensity as a strong Category 4 hurricane while approaching the northern Gulf Coast, with maximum sustained winds of 150 mph (240 km/h) and a minimum central pressure of 929 millibars (27.4 inHg). On August 29, the 16th anniversary of Hurricane Katrina making landfall, Ida made landfall near Port Fourchon, Louisiana, devastating the town of Grand Isle. Ida weakened steadily over land, becoming a tropical depression on August 30, as it turned northeastward. On September 1, Ida transitioned into a post-tropical cyclone as it accelerated through the Northeastern United States, breaking multiple rainfall records in various locations before moving out into the Atlantic on the next day. Afterward, Ida's remnant moved into the Gulf of St. Lawrence and stalled there for a couple of days, before being absorbed into another developing low-pressure area early on September 5.

The precursor to Ida caused catastrophic and deadly flash flooding in Venezuela. Ida knocked down palm trees and destroyed many homes in Cuba during its brief passage over the country. Throughout its path of destruction in Louisiana, more than a million people in total had no electrical power. Widespread heavy infrastructural damage occurred throughout the southeastern portion of the state, as well as extremely heavy flooding in coastal areas. New Orleans' levees survived (unlike during Katrina), though power line damage was extensive throughout the whole city. There was also substantial plant destruction in the state. Numerous tornadoes were spawned by Ida as it moved over the Eastern United States. The remnants of the storm produced unexpectedly severe damage in the Northeastern United States on September 1–2. Several intense tornadoes and catastrophic flash flooding swept through the entire region, which had already been impacted by several tropical cyclones, Elsa, Fred, and Henri during July and August. The flooding in New York City prompted the shutdown of much of the transportation system.

Ida is the sixth-costliest tropical cyclone on record, and the fifth-costliest Atlantic hurricane in the United States, having caused at least $75.25 billion (2021 USD) in damages. Of this total, at least $18 billion was in insured losses in Louisiana, $250 million was in Cuba, and $584 million was from agriculture damage in the U.S., surpassing Hurricane Ike of 2008. CoreLogic estimated that Ida caused an estimated $16 to 24 billion in flooding damage in the Northeastern United States, making it the costliest storm to hit the region since Hurricane Sandy in 2012, with an estimated $44 billion in insured loss.

A total of 112 deaths were attributed to Ida, including 92 in the United States and 20 in Venezuela. In the United States, 32 deaths were in New Jersey, 30 in Louisiana, 18 in New York, 5 in Pennsylvania, 2 in Mississippi, 2 in Alabama, 2 in Maryland, 1 in Connecticut, and 1 in Virginia. There was also a remarkable number of hospitalizations and deaths in the Greater New Orleans Area as a result of carbon monoxide poisoning while using portable gas generators with inadequate ventilation, including three in a family of four in Marrero, Louisiana on September 1, 2021.

Meteorological history

A weak tropical wave moved off the coast of Africa and moved into the Atlantic Ocean on August 14. The wave moved slowly westward through the monsoon trough without showing any signs of organization over the next several days. On August 21, the wave entered a trade wind environment west of 45°W accompanied by a large area of convection, or thunderstorms, that was elongated from east to west. As the wave moved over the Windward Islands, the convective coverage increased at which point the National Hurricane Center (NHC) began to the track the system as it continued westward into the Caribbean Sea. The next day, the wave interacted with a broad area of low-pressure over the north coast of South America, which led to the formation of a much larger broad low-pressure characterized by spots that were near or below 1006 mbar (29.71 inHg) over the southwestern Caribbean Sea by late the same day. On August 25, a vorticity maximum emerged from the eastern side of the larger low-pressure area and convection became concentrated and better organized around it, prompting the NHC to assess this disturbance as a high likelihood of development as it turned north-northwestward. The system continued to further organize and obtain a better defined circulation the next day to the south of Jamaica. At 12:00 UTC on August 26, the system had attained sufficient organization to be classified as Tropical Depression Nine, about 115 mi (185 km) south-southwest of Negril, Jamaica. Upon its development, the depression was moving north-northwestward before turning northwestward a few hours later, steered around the southwestern side of a subtropical ridge located over the western Atlantic Ocean. Favorable factors in the system's further development included warm waters of the northwestern Caribbean Sea, low wind shear, and a moist environment.

Late on August 26, at 18:00 UTC, a Hurricane Hunters flight indicated that the depression intensified into Tropical Storm Ida 130 mi (210 km) Southeast of Grand Cayman, Cayman Islands. Initially, the storm had an asymmetric structure, with its strongest winds and deepest convection located east of the center. This was due to some southwesterly wind shear, which gradually lessened. As Ida moved through the Cayman Islands and toward northwestern Cuba, its structure improved, with more outflow and rainbands. The convection also organized into a central dense overcast (CDO). Ida then rapidly intensified, with its winds increasing by 35 mph (55 km/h) in just over 11 hours. Late on August 27, at 18:00 UTC, the NHC upgraded Ida to Category 1 hurricane status, based on observations made by the Hurricane Hunters. Around the same time, the hurricane made its first landfall on Cuba's Isle of Youth with sustained winds of 80 mph (130 km/h) and a minimum central pressure of 987 mbar (29.15 inHg). After crossing over, Ida made its second landfall at 23:25 UTC at Playa Dayaniguas in Pinar del Río, Cuba, with the same winds speeds and a slightly higher 988 mbar (29.18 inHg) pressure. The system continued northwestward and its center emerged over the southeastern Gulf of Mexico between 01:00–02:00 UTC on August 28. Although it did not lose any strength, land interaction and entrainment of dry air into the hurricane's southwestern quadrant as Ida crossed Cuba inhibited further intensification, and little change in strength occurred during the first several hours after it reached the Gulf.

During the day-time hours of August 28 microwave satellite imagery and Cuban radar data showed Ida's central core to be reorganizing with the formation of a convective ring around the center. This, combined with the favorable conditions of light vertical wind shear and warm sea surface temperatures, led to a second, and more significant, period of rapid intensification that commenced around 12:00 UTC on August 28. Ida intensified to Category 2 strength by 00:00 UTC on August 29, and into a Category 4 hurricane six hours later, as it moved northwestward toward the Louisiana coast. At around 12:00 UTC that day, Ida reached its peak intensity, with 1-minute sustained wind speeds of 150 mph (240 km/h) and a minimum central barometric pressure of 929 mbar (27.43 inHg), while located not far southwest the mouth of the Mississippi River. During this intensification phase, the maximum winds increased 70 mph (110 km/h) and the central pressure dropped 57 mbar (1.683 inHg). At peak, the hurricane displayed a pronounced satellite presentation, with a near-symmetrical structure and a well-defined eye with an impressive stadium effect visible. Strengthening was then halted as the storm began an eyewall replacement cycle, forming a second, larger eyewall around the first one, but Ida remained near its peak intensity. At 16:55 UTC, Ida made its third, and final, landfall near Port Fourchon, Louisiana, with sustained winds of 150 mph (240 km/h) and a central pressure of 931 mbar (27.49 inHg), tying the 1856 Last Island hurricane and Hurricane Laura as the strongest landfalling hurricane on record in Louisiana, as measured by maximum sustained wind, and trailing only Hurricane Katrina, as measured by central pressure at landfall. A ship at sea near the point of landfall verified this intensity, with reported gusts as high as 172 mph (277 km/h).