Hurricane Irma (2017)

Date: August 30, 2017 to September 12, 2017

Place: Several islands in the Caribbean, Florida, Georgia, South Carolina

Result: Irma was one of the strongest hurricanes ever to form in the Atlantic Ocean. It was responsible for forty-seven deaths in the Caribbean and the southeastern United States. The hurricane was the fifth-costliest in US history, causing an estimated $50 billion in damage.

Overview

Hurricane Irma was a powerful storm that formed in the Atlantic Ocean in late August 2017. Irma began its life similar to many other Atlantic hurricanes. It started out on August 27 as a disorganized wave of thunderstorms that moved into the ocean from the west coast of Africa. If atmospheric conditions are right and water temperatures are warm enough, these waves can turn into strong storms. This wave of thunderstorms fed on the warm waters of the Atlantic and began to grow larger. What set the system apart is that it intensified so quickly it became a tropical storm soon after leaving the coast. A tropical storm is a weather system with wind speeds greater than 39 miles per hour (63 kilometers per hour).

Within thirty hours of becoming a tropical storm on August 30, Irma had strengthened into a major hurricane. Hurricanes have sustained wind speeds greater than 74 mph (119 km/h). A major hurricane is a category 3 storm or higher, with wind speeds greater than 111 mph (178 km/h). It is unusual for a tropical storm system to become so strong while still over the eastern Atlantic Ocean. As Irma began to approach the Leeward Islands on September 5, it grew into a powerful category 5 storm. A category 5 hurricane is the highest classification issued by the National Weather Service. It has sustained winds greater than 157 mph (253 km/h), and it is capable of causing catastrophic damage. Irma’s sustained winds reached 180 mph (290 km/h) on September 5 and 6, making it the most powerful hurricane ever recorded in the open waters of the Atlantic Ocean. Other hurricanes had stronger winds, but those were recorded while the storms were over the Gulf of Mexico or Caribbean Sea. Irma was one of only seven Atlantic hurricanes in history ever to have wind speeds of 180 mph or greater.

Irma maintained 180 mph wind speeds when it made its first landfalls on the small islands of Barbuda and St. Martin on September 6. It also struck one of the British Virgin Islands. Irma passed north of Puerto Rico, Hispaniola, and the US Virgin Islands but still buffeted those islands with rain and strong winds. The storm kept its category 5 status for about sixty hours, the second-longest period on record for an Atlantic hurricane. The storm weakened slightly as it moved over the southern Bahamas, and regained category 5 status before hitting the northern coast of Cuba on September 9.

Irma’s encounter with land weakened it to a category 2 storm, but it again picked up strength as it headed north toward Florida. Irma was a category 4 storm with winds of 132 mph (212 km/h) when it made landfall September 10 at Cudjoe Key in Florida. The storm packed winds of 115 mph (185 km/h) when it hit the Florida mainland hours later at Marco Island. Irma weakened over land, but it was still at category 1 strength when it passed over the heavily populated areas of Tampa and Orlando on September 11. Irma was downgraded to a tropical storm as it pushed into northern Florida and Georgia. It became a low-pressure system on September 12 over Alabama before breaking apart over Missouri the next day.

Impact

Irma devastated many of the Caribbean islands it impacted and caused severe flooding and damage in the United States. Storm surges as high as 8 feet (2.4 meters) were recorded in Barbuda. Large storm surges were also recorded in the US Virgin Islands. Storm surges in Cuba reached about 10 to 11 feet (3 to 3.4 meters). In Florida, the surge ranged from 5 to 8 feet (1.5 to 2.4 meters) in the Florida Keys to 6 to 10 feet (1.8 to 3 meters) on the mainland. Irma dumped an average of 10 to 15 inches (25.4 to 38 centimeters) of rain across the Caribbean and Florida. Some areas of Florida received as much as 21.7 inches (55 centimeters). Major flooding was reported in many areas in Puerto Rico and northern Cuba. Flooding was also widespread across much of central and northern Florida and parts of Georgia. Jacksonville, Florida, was hit by some of the worst flooding in its history. Parts of the city were inundated by more than five feet of water. Moderate flooding was reported as far north as South Carolina.

The powerful winds from Irma destroyed about 95 percent of the structures on Barbuda. The storm rendered the island virtually uninhabitable, and most of the island’s more than 1,600 residents were evacuated to nearby Antigua. Irma also destroyed an estimated 90 percent of the structures on St. Martin. Both the British and US Virgin Islands suffered severe damage with power lines downed and numerous homes and businesses destroyed. The trees on St. Thomas and St. John in the US Virgin Islands were almost completely stripped of their leaves.

In the United States, the Florida Keys were hit hardest by Irma. About 25 percent of the structures in the lower Keys were destroyed; another 65 percent suffered significant damage. On the Florida mainland, Irma downed power lines and trees in Marco Island, Everglades City, and Naples. More than 1,500 buildings were damaged in Collier County, and more than 1,000 homes were damaged in neighboring Miami-Dade County. An estimated 50 percent of Miami-Dade’s agricultural capability was destroyed by the storm. Irma’s winds damaged thousands of structures in central Florida, with an estimated 450 homes destroyed in Brevard County. The storm caused about $760 million in damage to the area’s orange groves.

Irma was responsible for forty-seven direct deaths—deaths that result from the hurricane’s winds, flooding, or storm surge. Thirty-seven of those deaths were reported in the Caribbean; ten deaths occurred in the United States. An additional eighty-two deaths in the United States were indirectly attributed to Irma. Indirect deaths include deaths from heart attacks, house fires, and electrocutions that may occur days after the storm. Irma caused an estimated $50 billion in damage in the United States. It was the fifth-costliest US storm on record. Two of the storms above Irma on the list—Harvey ($125 billion) and Maria ($90 billion)—also occurred in 2017.

Bibliography

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