Severe weather can strike any part of the world, but every year the Atlantic hurricane season brings heavy rain, strong winds, storm surges, and sometimes catastrophic devastation to areas from the Caribbean islands and Central America, all the way up through the United States and into Canada. Forecasters at the Miami-based National Hurricane Center closely monitor these storms from their formation until they dissipate. This year, the 2024 season was anticipated to be highly active, delivering the earliest Category 5 Atlantic hurricane on record.
So, how do hurricanes form, and what do the different categories signify? Hurricanes typically begin as tropical waves merging with warm ocean waters, often being fuelled by thunderstorms. As warm ocean air rises into the weather system, it moves west, creating a low-pressure area beneath it. This phenomenon leads to the formation of clouds and thunderstorms. Hurricanes are characterised by maximum sustained winds of 74 mph (120 kph) or higher. A tropical cyclone with winds between 39 and 73 mph (63 kph to 120 kph) is known as a tropical storm, while winds below 39 mph classify as a tropical depression.
Hurricanes are most prevalent during the Atlantic basin’s hurricane season, occurring annually from June 1 to November 30. The Saffir-Simpson Hurricane Wind Scale categorises hurricanes from one to five, with Category 1 being the least severe, ranging from 74 to 95 mph. As hurricanes progress up the scale, they become increasingly powerful. Major hurricanes are designated as Category 3 or higher, starting at maximum sustained winds of 111 mph (180 kph).
A Category 5 hurricane is deemed catastrophic, causing widespread destruction by destroying houses, cutting power to vast areas, isolating communities, and damaging infrastructure like roads and bridges. Such hurricanes have the potential to render large areas uninhabitable for weeks or longer. The impact of a hurricane varies depending on its strength and landfall location. Even a moderately weak hurricane can result in major damage and fatalities if it strikes a vulnerable community or crucial infrastructure.
The deadliest hurricane in US history is the 1900 Galveston hurricane in Texas, claiming at least 8,000 lives, destroying numerous buildings, and inflicting hundreds of millions of dollars in damage by modern standards. Other notably catastrophic hurricanes include Hurricane Maria in 2017, which caused over 3,000 fatalities, and Hurricane Katrina in 2005, claiming more than 1,300 lives.
Understanding the formation and categories of hurricanes is crucial for preparedness and response efforts to mitigate the potential devastation they can bring. Stay informed and stay safe during hurricane season.