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article imageWhat are the factors that determine the severity of hurricanes?

By Karen Graham     Sep 1, 2019 in Science
Hurricane Dorian is classified as a Category 5 storm on the Saffir-Simpson scale, however, it takes more than winds to determine a storm's ferocity. And if we add several more factors, it doesn't really matter if a storm is a Category 5 or 6 hurricane.
Hurricane Dorian, with wind speeds of 185 mph and gusts of over 220 mph is a full-fledged Category 5 tropical cyclone on the Saffir-Simpson scale.
This classification covers major storms that have wind speeds 157 mph (252 kph) or higher. This is because, in Category 5 storms, we can expect catastrophic damage and even loss of life.
A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
GOES 16 satellite imagery of Hurricane Dorian on August 31  2019 at 12:26 p.m. ET.
GOES 16 satellite imagery of Hurricane Dorian on August 31, 2019 at 12:26 p.m. ET.
GOES 16 satellite imagery
There are other factors besides wind speed that determine if a storm is the "worst" or "biggest" one ever experienced. Now, Dorian is the strongest and most intense hurricane to hit the Bahamas on record. And there is no doubt that this hurricane is capable of causing catastrophic damages.
But let's take a stroll down memory lane - You might be surprised to learn that wind speed, lowest minimum central pressure, and damage costs also need to be taken into consideration in determining what is the strongest hurricane.
The strongest hurricanes to hit the US mainland
Hal Needham, a hurricane scientist at Louisiana State University, explained on the weather site WXshift in 2017 that a storm's category doesn't fully convey how much damage it could cause.
Debris and the remnants of the Rt. 626 bridge over the Rockfish River. Located in Howardsville  Nels...
Debris and the remnants of the Rt. 626 bridge over the Rockfish River. Located in Howardsville, Nelson County. No. 69-2109, Virginia Governor's Negative Collection, Library of Virginia.
The Library of Virginia @ Flickr Commons
1. Camille (Mississippi, Louisiana, Virginia) - became a Category 5 storm. Camille's highest sustained wind speed reached 175 mph (280 kph) and its lowest central pressure reached 900 mb. Damages from Camille totaled $1.42 billion, and 259 people lost their lives.
2. Hurricane Wilma in 2005 probably holds the record for intensifying into a Category 5 storm the fastest. Wilma's highest sustained wind speed was also 175 mph (280 kph), but the storm's central pressure dipped to 882 mb. Wilma did $27.4 billion in damages and 87 people lost their lives.
Hurricane Wilma was the most intense tropical cyclone ever recorded in the Atlantic basin, and the second-most intense tropical cyclone recorded in the Western Hemisphere, after Hurricane Patricia in 2015.
A car makes its way down a flooded avenue in Miami  Florida on October 24  2005 hours after hurrican...
A car makes its way down a flooded avenue in Miami, Florida on October 24, 2005 hours after hurricane Wilma swept through the area
Roberto Schmidt, AFP/File
3. Irma, also in 2017, was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Maria two weeks later. Irma had sustained winds of 180 mph (285 kph) and a central pressure that dropped to 914 mb. Irma caused a whopping $77.16 billion in damage and 52 people were directly killed by the storm.
4. Maria in 2017 was the thirteenth named storm, eighth consecutive hurricane, the fourth major hurricane, second Category 5 hurricane, and deadliest storm of the 2017 Atlantic hurricane season. The Atlantic was very busy that year. Maria had sustained winds of 175 mph (280 kph) and its central pressure dropped to 908 mb. Maria caused a whopping $91.61 billion in damage and 3,059 people lost their lives.
5. Tropical Storm Harvey made landfall in Texas as a Category 4 hurricane on Aug. 25, 2017, dumped unprecedented amounts of rain on areas of the state, causing devastation in the Houston area. One rain gauge picked up more than 51 inches of rainfall, according to NOAA.
People walk through the flooded waters of Telephone Rd in Houston in August 2017 during tropical sto...
People walk through the flooded waters of Telephone Rd in Houston in August 2017 during tropical storm Harvey
Thomas B. Shea, AFP/File
Harvey's sustained wind speed was 130 mph (215 kph) and its central pressure only dropped to 937 mb. But because of the deluge of rain, damages amounted to $125 billion with 69 people directed killed because of the storm. Harvey is tied with Katrina in 2005 as the costliest hurricane on record.
6. Hurricane Katrina was a Category 5 storm which decimated New Orleans in 2005. It is essentially tied with Michael as the third most intense hurricane to make U.S. landfall but was by far the costlier storm. Katrina had maximum sustained winds of 175 mph (280 kph) and a minimum pressure of 902 mb.
Like Hurricane Harvey, Katrina also caused $125 billion in damages and it is estimated that between 1,245 and 1,836 people lost their lives.
Description of the 5 categories in the Saffir-Simpson hurricane wind scale
Description of the 5 categories in the Saffir-Simpson hurricane wind scale
AFP, AFP
If hurricanes outside the continental U.S. are factored in, two hurricanes to strike Puerto Rico - San Felipe (1928) and David (1979) - rank among the most intense in history. And there are notable records for tropical cyclones around the globe. As an example, Tropical Cyclone Mahina struck Australia in 1899 and produced a storm surge of 30 feet.
Then, if you consider the death toll in determining a monster storm, the largest tropical cyclone death toll on record is the Bangladesh Cyclone of 1970. Close to 500,000 people died due to the storm surge, according to the National Weather Service.
The point is simply that once winds get over 130 mph, regardless of a storm's category, they are all major storms with the ability to cause severe damage and loss of life.
More about Hurricanes, SaffirSimpson scale, barometric pressure, wind speed, cost of damages
 
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