September 23, 2023

By Jennifer Grey | CNN Meteorologist

As soon as a tropical storm strengthens right into a hurricane, it earns a class designation on the Saffir-Simpson Hurricane Wind Scale: 1 via 5.

Figuring out about every class will help predict what harm an incoming storm could inflict – and the way finest to arrange.

The classes are outlined by wind pace, with a storm of Class 3, 4, or 5 thought of a significant hurricane. And harm is exponential as wind pace will increase, which means a robust Class 3 storm might do as much as 60 instances as a lot harm as a weak Class 1 storm.

However it’s not all the time so simple as ticking up from 1 to five.

Hurricanes carry many dangers not adequately conveyed by the wind speed-based scale, together with:

• Storm surge – when winds push water onto shore – which accounted for about half of hurricane fatalities between 1963 and 2012, in line with a 2014 report within the Bulletin of the American Meteorological Society;

• Rainfall-induced flooding and mudslides, which made up a few quarter of such deaths, the report reveals;

• A storm’s ahead pace: Slower storms are extra harmful, with sturdy gusts or rainstorms that pound the identical areas for hours or days;

• Tornadoes, which might spawn by the dozen from any hurricane.

Nonetheless, the Nationwide Hurricane Heart makes use of classes – set by sustained wind pace – to estimate doable property harm from hurricanes. Right here’s what’s anticipated in every:

Class 1: 74-95 mph

Sustained winds are sufficient to blow shingles off roofs and harm gutters and vinyl siding, the Nationwide Oceanic and Atmospheric Administration mentioned.

These winds can also uproot bushes and convey down branches, inflicting energy outages and extra property harm. They will harm energy traces instantly, too.

• Hurricane Nicole, a Class 1 storm, made landfall in November 2022 alongside Florida’s East Coast and impacted locations nonetheless then recovering from Hurricane Ian lower than two months earlier. Nicole brought about important seaside erosion and brought about greater than $1 billion in damages, in line with NOAA.

Class 2: 96-110 mph

Sustained winds might trigger as a lot as 20 instances the harm as these of a Class 1 storm, together with intensive harm to a house’s roof and siding.

Quite a few bushes and energy traces will probably be broken, blocking roads, damaging property and knocking out energy for days, if not weeks.

• Hurricane Delta struck Louisiana’s coast in October 2020 with winds of 100 mph and made landfall simply 12 miles east of the place Hurricane Laura had come ashore simply six weeks earlier. Delta blew away many tarps on roofs broken by Laura and did intensive harm to bushes, houses and companies. It additionally dumped greater than a foot of rain throughout South Louisiana, creating extended flooding.

Class 3: 111-129 mph

Now in “main hurricane” territory, wind harm is way more widespread. Properly-built houses and different buildings might undergo main harm, and roofs will maintain heavy harm. Quite a few bushes can be broken or uprooted.

“Electrical energy and water can be unavailable for a number of days to weeks after the storm passes,” NOAA mentioned.

• Hurricane Katrina was a Class 3 storm that struck through the busy 2005 Atlantic hurricane season. It first made landfall alongside the Florida coast at Class 1 power earlier than quickly intensifying within the Gulf of Mexico to Class 5. It weakened earlier than making landfall in southeast Louisiana as a Class 3 storm.

Storm surge was estimated at shut to twenty toes alongside the Mississippi-Alabama border, and estimated winds reached as excessive as 140 mph close to Grand Isle, Louisiana. Levee breaches despatched water flooding into a lot of New Orleans, forcing individuals onto rooftops for rescue. Katrina killed greater than 1,800 individuals, left as many as 600,000 households displaced for a minimum of a month and have become the costliest storm on report, in line with NOAA.

Class 4: 130-156 mph

Catastrophic harm may result from these winds. Properly-built houses can be closely broken, with many of the roof blown away. Timber and energy traces can be down. Water and energy companies might be out for months, with the hardest-hit locations uninhabitable for weeks.

• Hurricane Ian made landfall in September 2022 alongside the southwest Florida coast as a Class 4 storm. It killed 150 individuals and have become the most expensive storm on report in Florida. Its huge measurement and snail’s tempo made it exceedingly harmful, with 150-mph winds that battered coastal communities for hours.

Ian introduced report storm surge to Fort Myers and Naples, estimated at 10 to fifteen toes, NOAA mentioned. For days after landfall, the storm dumped unprecedented volumes of rain throughout Florida, triggering large river flooding within the weeks that adopted.

Class 5: 157 mph or better

These are essentially the most highly effective storms on Earth. Most well-built houses can be destroyed, many stripped to the inspiration. Energy outages might final for months, and the areas hardest hit might be uninhabitable for months.

• Hurricane Andrew in August 1992 was one of many worst storms to ever hit the US, devastating a complete area after it made landfall close to Homestead, Florida. Andrew grew from a Class 1 storm to a Class 5 storm in simply 36 hours, with most winds close to Homestead round 165 mph, in line with NOAA.

On the time, Andrew was the “costliest and most damaging hurricane ever to hit the US,” the Nationwide Climate Service mentioned.

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