September 23, 2019

Three weeks ago, on September 1, Hurricane Dorian savaged the Bahamas, a chain of islands east of Florida in the Atlantic Ocean. In the slang of the islands, Dorian mashed up (devastated) much of Grand Bahama and the Abaco Islands in the northwestern part of the archipelago. Dorian, one of the strongest hurricanes on record to strike the Bahamas, killed at least 53 people there. That number will almost certainly skyrocket, however, as more than 600 people remain missing.

Hurricane Dorian’s high winds and floods destroyed much of Freeport, Grand Bahama, seen here on Sept. 5, 2019. Credit: © Adam DelGiudice, AFP/Getty Images

Dorian struck the Bahamas as a category 5 storm on the Saffir-simpson scale, which measures hurricane intensity. Category 5 is the strongest hurricane rating, with winds above 157 miles (252 kilometers) per hour. Hurricanes of this strength typically occur about every three years, but Dorian marked the fourth consecutive year that a category 5 hurricane has struck the Caribbean, with two striking in 2017 when Irma and Maria killed more than 3,000 people, mostly in Puerto Rico. Hurricanes of all categories can cause terrible destruction and loss of life, but category 5 hurricanes are labeled “catastrophic” by the United States National Oceanic and Atmospheric Administration (NOAA). Winds that strong will destroy most framed houses by tearing away roofs and collapsing walls. They will flatten trees and electric power poles and leave residential areas uninhabitable for weeks or months. Increases in the intensity of hurricanes and other bad weather align with what scientists expect as the world’s climate continues to change.

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Bahamas.
Credit: WORLD BOOK map

Dorian formed as a tropical depression over the Atlantic Ocean on August 24. A tropical depression is a low-pressure area surrounded by winds that have begun to blow in a circular pattern. Dorian developed into a hurricane four days later. The storm rapidly gained size and strength, reaching category 5 status by September 1. That day, the massive hurricane hit Elbow Cay and Great Abaco Island before moving on to Grand Bahama, where Dorian lingered for more than 24 devastating hours. Dorian lashed the islands with sustained winds of 185 miles (300 kilometers) per hour and gusts over 220 miles (350 kilometers) per hour. Storm surges (sudden onrushes of seawater) and torrential rains caused deadly flooding in many parts of the low-lying islands.

On Sept. 5, 2019, people search through the ruins of their home in Marsh Harbour, Great Abaco Island, days after Hurricane Dorian hit as a category 5 storm. Credit: © Jose Jimenez, Getty Images

Dorian then spun away along the coasts of eastern Florida, Georgia, and South Carolina, greatly diminishing to a category 1—but still dangerous—hurricane before hitting Cape Hatteras in North Carolina’s Outer Banks on September 6. From there, Dorian further downgraded to an extratropical cyclone (a stormy low pressure system) and raced northward off the U.S. east coast. On September 7, Dorian’s final gasp brought heavy rains and fierce winds to Newfoundland and Nova Scotia in Canada. The storm at last dissipated near Greenland on September 10.

Dorian threatened many areas, and states of emergency were declared in several Caribbean and Atlantic islands and eastern U.S. states. But the storm’s rapid degradation after striking the Bahamas greatly reduced its deadliness. Dorian still killed people—directly or indirectly—outside the Bahamas, however, including one person in Puerto Rico, six people in Florida, and three people in North Carolina. Direct deaths are caused by such things as blown debris, flooding, or falling trees. Indirect deaths include people who die by accident or heart attacks while involved in storm-related activities, such as clearing trees or boarding up houses. They also include those who die in car accidents trying to evacuate.

October 20, 2017

On Monday, October 16, tropical storm Ophelia roared through the northeastern Atlantic Ocean, killing three people in Ireland and causing damage in parts of the United Kingdom. Ophelia, one of the most powerful storms ever recorded in that part of the Atlantic, was an unusual occurrence. The last such storm to reach Ireland, Hurricane Debbie, killed 11 people on the island in 1961.

Tropical storm Ophelia slammed the coasts of Ireland and Wales on Oct. 16, 2017. This photo shows Ophelia-driven waves battering the sea wall at Porthcawl in southern Wales. Credit: © Leighton Collins, Shutterstock

Major Atlantic storms typically form in waters off the central and southern coasts of west Africa. Trade winds then carry them westward toward the Caribbean Sea and the southeastern United States. Ophelia began as a cluster of storms farther north, gathering strength near the Azores before driving northeast toward Europe. Classified as a mid-strength Category 3 hurricane, Ophelia was the strongest-ever storm that far east in the Atlantic Ocean. Downgraded to a tropical storm on its jet stream-led course to Ireland, Ophelia remained dangerous. Ireland’s national weather service issued a red alert for severe weather, warning of “violent and destructive gusts” and “potential loss of life.”

This satellite image shows Ophelia coiling over Ireland on Oct. 16, 2017. Credit: NASA

The storm made landfall in Ireland on Monday morning with wind gusts of 109 miles (176 kilometers) per hour at Fastnet Rock, the country’s most southerly point. Torrential rains lashed the southwestern counties of Cork and Kerry, where schools, businesses, public buildings, and hospitals were closed ahead of the storm. Public transportation ceased running in much of Ireland, ferries and flights were canceled, and people were warned to stay indoors.

Ophelia quickly swamped all of the Republic of Ireland, whipping Wales hard too across the Irish Sea. Electric power was lost in many areas of both Ireland and Wales, trees were blown down (causing all three of the deaths in Ireland), rooftops were ripped away, and storm surges breached sea walls in many places. Winds and heavy rains then hit Northern Ireland and Scotland as Ophelia raced back out to sea, dissipating but still carrying severe weather as far as Norway. (The United Kingdom is divided among the political divisions of Wales, Northern Ireland, Scotland, and England.)

Ophelia affected other areas, too. In Portugal and Spain, strong winds from the storm fanned wildfires that killed 44 people. Ophelia blew smoke from the fires—and dust from Sahara sandstorms—over England, where the London sky turned an eerie smoky orange. Ophelia was the 10th hurricane of a busy and deadly 2017 Atlantic storm season. Ophelia’s rare path illustrates how rising global temperatures are expanding the range of powerful storms around the world.

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.

October 26, 2015

Hurricane Patricia, seen on Friday, October 23, 2015, was the strongest storm ever recorded in the Western Hemisphere. (NOAA)

On October 21, a small tropical storm formed from a system of thunderstorms in the Pacific Ocean off the coast of Mexico. Just two days later, that storm became became Hurricane Patricia, the strongest storm ever recorded in the Western Hemisphere, with winds of 200 miles (320 kilometers) per hour. Soon after, the storm hit coastal villages in Jalisco in western Mexico. Then, less than a day later, Hurricane Patricia fizzled out and was gone. The storm’s rapid development and disappearance caused scientists to ask new questions about extreme weather’s connection to worldwide climate cycles.

Hurricanes are powerful, swirling storms that begin over warm seas. The storms then move westward, often toward the poles. When a hurricane hits land, it can cause great damage through fierce winds, torrential rain, flooding, and huge waves crashing ashore.

Hurricanes require a special set of conditions, including ample heat and moisture, that exist primarily over warm, tropical oceans. For a hurricane to form, there must be a sufficiently warm layer of water at the top of the sea. This warm seawater evaporates into the air. The moisture then condenses (changes into liquid), forming clouds. As the moisture condenses, it releases heat that warms the air, causing the air to rise. The warm, rising air creates a region of relatively low atmospheric pressure. (Atmospheric pressure is the weight of the air pressing down on a given area.)

Air tends to move from areas of high atmospheric pressure to areas of low pressure, creating wind. Earth’s rotation can cause the wind to swirl as it blows into a low-pressure area. As the swirling winds increase in speed, more ocean water evaporates and condenses. The moisture releases more heat, further warming the storm’s core. The warm air rises faster, increasing surface wind speeds, and so on. This cycle, called a positive-feedback loop, continues to strengthen the hurricane. Only when friction between the air and the water surface becomes great enough will a hurricane weaken.

Scientists still aren’t sure why such hurricanes as Patricia intensify so quickly. In Patricia’s case, some of the energy may have come from exceptionally warm surface waters in the region, caused by this year’s developing El Niño event. El Niño is part of the interaction between Earth’s atmosphere and the tropical waters of the Pacific Ocean. An El Niño occurs about every two to seven years, and it can affect climate throughout the world. The El Niño of 2015 is shaping up to be one of the strongest events on record. Studying Hurricane Patricia’s development will help meteorologists make better predictions concerning extreme weather in regions affected by El Niño.

Despite Patricia’s incredible intensity, it caused relatively little damage to Mexico. It struck an area of the country where few people live. Evacuation efforts were also effective. The hurricane’s enormous strength quickly waned over land, as tall coastal mountains helped beak up the storm. Overall, fewer than 10 people died and damages were not expected to exceed $200 million.

September 15, 2014

Hurricane Odile (oh-DEEL) pummeled beach resorts along Mexico’s Baja California peninsula with winds of up to 125 miles (200 kilometers) per hour, confining thousands of tourists to their hotels. The government of Mexico put the area on high alert, warning of falling trees, storm surges, flooding, and landslides. Electric power lines and traffic signals are reported down in Los Cabos, a resort community on the southern tip of the peninsula.

A satellite image of Hurricane Odile released by the U.S. National Oceanic and Atmospheric Administration (NOAA) on September 15, 2014. (NOAA)

The U.S. National Hurricane Center in Miami had predicted that the Odile would make landfall as a category four storm, but it actually lost strength as it reached the Pacific Coast. Nevertheless, Odile is the strongest hurricane to ever hit the peninsula, dumping six months’ worth of rain in an hour. A meteorologist for “The Weather Channel” reported “mind-boggling” readings of 7 to 11 inches (17 to 27 centimeters) of rain in just one hour but noted the monitoring devices may be malfunctioning.

Additional World Book articles:

• The Forecast: Better Weather Prediction Ahead (a special report)
• How the Ocean Affects Climate (a special report)

August 7, 2014

People in the Hawaiian islands today are bracing for two storms–Hurricane Iselle and Tropical Storm Julio. The islands are rarely directly hit by hurricanes, so for two storms to make landfall on the Hawaiian Islands in 3 days is a rare event. Yesterday, Iselle had maximum sustained winds of 100 miles (161 kilometers) per hour and Julio of 65 miles (100 kilometers) per hour. Iselle was expected to reach the Big Island, the island of Hawaii, this afternoon or evening. Julio is further out and is expected to make landfall Monday (August 11).

Two major storms from the east are expected to make landfall in Hawaii over the next few days—Hurricane Iselle and Tropical Storm Julio. (World Book map; map data © MapQuest.com, Inc.)

The U.S. Coast Guard predicted storm surges and high surf and the U.S. National Weather Service issued a flash flood watch that began early today. Residents of Hawaii were stocking up on bottled water and canned goods as they were warned to gather a 7-day disaster supply kit.

Additional World Book articles:

• Hurricane
• Hurricane (a research guide)

May 1, 2013

Scientists have discovered a hurricane on Saturn that is 20 times as large as the average hurricane on Earth. NASA’s Cassini spacecraft has provided scientists with the first close-up views of the enormous storm swirling around Saturn’s north pole. The hurricane swirls inside a mysterious six-sided feature first photographed in 2006. The hexagon is unlike anything seen on any other planet. The Cassini probe was able to photograph the storm in sunlight only after the planet’s north pole emerged from the darkness of its polar winter. Cassini’s orbit was also shifted so the probe would pass directly over the north pole.

The eye of the hurricane is about 1,250 miles (2,000 kilometers) wide. The clouds circling around the outer edge of the storm are moving at 330 miles  (530 meters) per hour. By contrast, the strongest hurricanes on Earth have winds of up to 200 miles (320 kilometers) per hour. Also, unlike hurricanes on Earth, which generally move, the Saturnian hurricane is locked onto the planet’s north pole. Scientists believe it has been churning for years.

A hurricane swirls around the north pole of Saturn, in a false-color infrared image taken by the Cassini space probe at a distance of about 261,000 miles (419,000 kilometers). Clouds shown in red are closer to the surface than those shown in green. (NASA/JPL-Caltech/SSI)

“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” noted Cassini imaging team member Andrew Ingersoll. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn’s hydrogen atmosphere.”

Hurricanes on Earth feed off warm ocean water. But there is no body of water close to these clouds high in Saturn’s atmosphere. Scientists suggest learning how these Saturnian storms use water vapor could provide greater understanding of how hurricanes on Earth are generated and sustained.

Additional World Book articles

• Jet Propulsion Laboratory
• Close encounters with Saturn (a special report)
• Probing the Planets (a special report)
• Space exploration 1997 (a Back in Time article)
• Space exploration 2004 (a Back in Time article)
• Space exploration 2008 (a Back in Time article)

November 5, 2012

The death toll from the massive storm that started out as Hurricane Sandy stands at 71 people in the Caribbean, 110 in the United States, and 2 people in Canada. The storm left at least 40 people dead in New York City. More than 1.8 million homes and businesses remain without electric power in the states of Connecticut, New Jersey, New York, Pennsylvania, and West Virginia, down from a peak of 8.5 million on October 30.

New York City’s 1.1 million public school students returned to class today. However, 57 school buildings are too damaged to be reopened, forcing some 34,000 students to be reassigned to other schools. At least 29 schools remain without electric power, and 8 buildings that normally house 24,000 students are currently being used as shelters for people left homeless by the storm.

The strong winds in hurricanes can push huge amounts of water onto land in a storm surge. Sandy's massive storm surges caused widespread devastation in parts of New York and New Jersey. (AP/Wide World)

An estimated 30,000 to 40,000 New Yorkers remain homeless, according to the office of Mayor Michael Bloomberg. At least 20,000 of the total were residents of public housing. In New Jersey, more than 5,000 people remain in shelters, and tens of thousands of people who evacuated are known to be living with friends or relatives.

Hurricane Sandy made landfall in the United States near Atlantic City, New Jersey, in the early evening of October 29. A record storm surge caused enormous damage along the Jersey Shore and in New York City, particularly in Queens and on Staten Island. As the storm moved inland, it collided with two other weather systems, including a burst of cold air sweeping down through the Canadian Plains. The combined storm brought high winds, freezing rains, and heavy snows to parts of West Virginia. In Pennsylvania, it caused power outages and flooding and forced numerous closures of roads, schools, and businesses. The storm left at least seven people dead in Pennsylvania and five dead in West Virginia.

Additional World Book articles:

• Federal Emergency Management Agency (FEMA)
• The Forecast: Better Weather Prediction Ahead (a special report)
• How the Ocean Affects Climate (a special report)

October 31, 2012

President Barack Obama, who has put campaigning on hold, accompanied New Jersey Governor Chris Christie today on a tour of areas of the Jersey Shore devastated by Hurricane Sandy. The storm made landfall on the night of October 29 along the New Jersey coast near the resort of Atlantic City. A storm surge flooded much of the city and tore up parts of the famed boardwalk. Governor Christie described the damage to the Jersey Shore as “incalculable,” and President Barack Obama declared a federal disaster area in eight New Jersey counties as well as in New York City and Long Island. Governor Christie, a Republican who supports Republican presidential candidate Mitt Romney, has gone out of his way to praise President Obama for his handling of the storm. “I spoke to the president three times yesterday,” he said during a televised interview. “He’s been incredibly supportive and helpful to our state and not once did he bring up the election.”

The death toll from the storm has been raised to at least 80, including 37 people in New York State. At least 8 million households and businesses remain without electric power, the U.S. Department of Energy announced today.

A fire fueled by high winds from Hurricane Sandy burned more than 100 houses in the New York City borough of Queens. Sections of Staten Island remain flooded. (World Book map)

In New York City, the storm flooded seven subway tunnels under the East River in what the chairman of the Metropolitan Transportation Authority characterized as the single most destructive disaster in the 108-year history of the subway system. Although parts of the system are running on a limited basis, rails and electrical equipment in the flooded tunnels will have to be cleaned before the entire network can reopen, which could take weeks.

The storm toppled thousands of trees in New York City and sparked numerous fires. Driven by the hurricane-force winds, one fire burned more than 100 houses in the borough of Queens. In Manhattan, flooding topped the sea wall in the financial district and triggered an explosion in a Consolidated Edison generating plant, cutting electric power to much of the island below mid-town. The area remains in the dark. However, the New York Stock Exchange reopened today, running on generator power, after being closed for two days. The last time the stock exchange shut down for so long because of the weather was during the Great Blizzard of 1888.

With offices reopening and the subway hobbled, many commuters drove into the city, creating massive gridlock. Drivers reported delays of hours, with cars and taxis lined up at major crossings and the entrances to reopened bridges and tunnels.

The famed Boardwalk in Atlantic City, New Jersey, suffered major damage as a storm surge caused by Hurricane Sandy devastated beaches on the Jersey Shore. (© age fotostock/SuperStock)

As Sandy moved inland, it collided with two other weather systems, including a burst of cold air sweeping down through the Canadian Plains. The combined storm brought high winds, freezing rains, and heavy snows to parts of West Virginia. In Pennsylvania, it caused power outages and flooding and forced numerous closures of roads, schools, and businesses. The storm left at least seven people dead in Pennsylvania and five dead in West Virginia.

Additional World Book articles:

• Federal Emergency Management Agency (FEMA)
• The Forecast: Better Weather Prediction Ahead (a special report)
• How the Ocean Affects Climate (a special report)