September 13, 2017

Last week, on September 6, the massive storm known as Hurricane Irma began ravaging the Leeward Islands of the eastern Caribbean Sea. The storm then roared over Puerto Rico and Cuba before reaching southern Florida on September 10. The storm has since weakened to a tropical depression and dissipated over land, but it continues to bring torrential rains as it passes up the southeastern coast of the United States. Irma’s week of havoc has killed 70 people, leaving a shattered landscape and record flooding in its wake.

The eye of Hurricane Irma centers on the island of Anguilla on Sept. 6, 2017. Emergency precautions on Puerto Rico and the Dominican Republic (at left) prepared residents for the approaching storm. Credit: CIRA/NOAA

Hurricanes are measured using the Saffir-Simpson scale of intensity. The scale is based on wind speed and the height of the resulting storm surge—that is, how much the sea level rises above normal high tide. The scale ranges from Category 1 (weak) to Category 5 (devastating). Irma formed as a low pressure and thunderstorm system over the Atlantic Ocean before consolidating into a massive storm in the eastern Caribbean Sea. As a Category 5 hurricane, Irma devastated parts of Antigua and Barbuda, the islands of Anguilla, St.-Barthélemy, and St.-Martin, and the British and U.S. Virgin Islands. Irma’s strength fluctuated as it roared over Puerto Rico, the Dominican Republic, Haiti, Cuba, the Turcs and Caicos Islands, and the Bahamas, alternating between categories 3 and 4 before reaching the Florida Keys. The storm weakened to a tropical storm over Florida, but still caused massive wind and water damage. Among the Caribbean Islands, Irma killed 43 people. Twenty-seven more people have died in the southeastern U.S. states of Florida, Georgia, and South Carolina. Those numbers will very likely rise.

On Sept. 11, 2017, the flattened devastation of Jost Van Dyke island in the British Virgin Islands reveals the destructive force of Hurricane Irma. Credit: UK Department for International Development (licensed under CC BY 2.0)

In the southeastern United States and the Caribbean, hundreds of roads are still blocked by high water, and many airports, schools, and office buildings remain closed. Millions of people have been displaced, and many areas are without electric power or drinking water. Humanitarian and military aid is arriving in the areas hit by Irma, providing shelter, medicine, and food and water, and helping with the beginning of a colossal cleanup. Damage from Irma is expected to top $200 billion, and repairs and reconstruction after the storm could take years. Irma is the strongest storm to hit the region since Hurricane Wilma in 2005.

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Hurricane Irma roared from east to west through the Caribbean Islands. Credit: WORLD BOOK map

Irma followed closely on the heels of Hurricane Harvey, which flooded the Texas coast, and preceded the formation of Hurricane Katia, which hit southern Mexico last weekend. An astounding fourth hurricane, Jose, chased Irma into the Caribbean before spinning off into the western Atlantic Ocean. Water temperatures in the Atlantic and Caribbean Sea are well above average, and massive storms feed off those warm waters. The expansion of high pressure areas—as well as a superabundance of moisture in the air—are ripe conditions for hurricane creation. They are also consistent with the effects of anthropogenic (human-caused) climate change.

October 11, 2016

On Oct. 7, 2016, people in Les Cayes, Haiti, search through the wreckage left by Hurricane Matthew days earlier. Credit: Julien Mulliez, UK Department for International Development (licensed under CC BY 2.0)

This past weekend, Hurricane Matthew ravaged the southeast Atlantic coast of the United States, causing flooding and accidents that killed at least 33 people in Florida, Georgia, South Carolina, North Carolina, and Virginia. The storm then weakened and turned out to sea, but flooding from heavy rains and storm surges continued in a number of areas. Matthew’s worst destruction, however, came days earlier when the hurricane made landfall in Haiti. There, the storm killed around 1,000 people and triggered a number of cholera cases. Deaths were also reported at sea and in the Dominican Republic, which shares the island of Hispaniola with Haiti.

A NASA satellite captured this image of Hurricane Matthew along the coast of Florida on Oct. 7, 2016. Credit: NASA’s Goddard MODIS Rapid Response Team

Hurricane Matthew formed as a tropical storm off the west coast of Africa in late September. The system strengthened as it prowled across the Atlantic Ocean, building into a hurricane as it entered the eastern Caribbean Sea. Peaking in strength at Category 5—the strongest hurricane rating with winds above 150 miles per hour (240 kilometers per hour)—Matthew scudded northwest and crashed into Haiti on October 4, devastating the country’s southwestern Tiburon Peninsula. Entire villages and farms were flattened or washed away, with contaminated water causing outbreaks of cholera. That same day, the storm lashed the eastern tip of Cuba, causing severe flooding in and around the city of Baracoa. Over the next two days, the storm rumbled over the Bahamas, doing its worst on Grand Bahama island just off the coast of Florida.

Hurricane Matthew rolled through the Caribbean Sea and up the southeast coast of the United States in early October 2016. Credit: WORLD BOOK map

Hurricane Matthew then skirted the southeast coast of the United States, where mass evacuations had cleared many people from harm’s way. From October 7 through October 9, the storm caused flooding from Saint Augustine, Florida, up to Fort Pulaski, Georgia; Charleston, South Carolina; and inland into North Carolina and Virginia. Savannah, Georgia, recorded the highest rain total during the storm—more than 17 inches (44 centimeters). Around Greenville, North Carolina, flooding washed out highways and bridges, stranded motorists, and forced people to the roofs of their homes. In that state, boat and aircrews rescued more than 1,000 people—700 in central Cumberland County alone. Evacuations of coastal areas were fairly successful, but inland areas were often caught off guard. The storm also knocked out electric power for more than 2 million people and forced the closures of thousands of business and schools—including the Walt Disney World Resort in Orlando, Florida, which closed for just the fourth time in its history.