HOW THE FURY OF A HURRICANE IS MEASURED: THE SAFFIR-SIMPSON HURRICANE SCALE (SSHS)

The way we measure hurricanes today is based on a scale developed in 1971 by the civil engineer Herbert Saffir and the meteorologist Robert Simpson, who at the time was the director of the U.S. National Hurricane Center in the US (NHC). By 1973 the scale widespread to the public.saffir

The preliminary scale proposal was developed by Saffir who in 1969 went on commission for the United Nations to study a low-cost housing in hurricane affected areas. Saffir realized there was no simple scale for describing the effects of a hurricane, so then through the mirroring of the Richter magnitude scale in describing earthquakes, he envisioned a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the NHC where Simpson added the effects of storm surge and flooding to have a more comprehensive scale.

Types of categories according to the National Oceanic and Atmospheric Administration (NOAA) from the US:

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LOOKING TO THE SCALE IN THE PRACTICE: SOME EXAMPLES

Category 5: Cataclysmic damage will occur.

Hurricane Isabel was the deadliest and strongest hurricane in the 2003 Atlantic hurricane season. The fifth hurricane and second major hurricane of the season, Isabel formed near the Cape Verde Islands from a tropical wave on September 6 in the Atlantic Ocean. It moved northwestward and within an environment of light wind shear and warm waters it steadily strengthened to reach peak winds of 165 mph (265 km/h) on September 11. After fluctuating in intensity for four days, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina with winds of 105 mph (165 km/h) on September 18. It quickly weakened over land and became extratropical over western Pennsylvania the next day fortunately, therefore directly, Isabel recorded 17 fatalities plus 34 indirectly, which seems low vs other hurricanes with lower intensity but penetrate farther in continentals lands with higher impact in fatalities.

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Image of Isabel Category 5 hurricane as seen from the ISS on September 15th, 2003. Image credit of Mike Trenchard. Earth Sciences & Image Analysis Laboratory. NASA Johnson Space Center.

Category 4: Catastrophic damage will occur.

Recently, Harvey was one of the most extremely destructive Atlantic hurricanes which became the first major hurricane to make landfall in the United States since Wilma in 2005 ending a record 12-year drought in which no hurricanes made landfall at such this level of intensity in this territory. In a four-day period, many areas received more than 40 inches (100 cm) of rain as the system meandered over eastern Texas and adjacent waters, causing catastrophic flooding. With peak accumulations of 51.88 in (131.8 cm), Harvey is the wettest tropical hurricane on record in the contiguous United States. The resulting floods inundated hundreds of thousands of homes, displaced more than 30,000 people, and prompted more than 17,000 rescues with recorded fatalities as of 83 people.HARVEY

Archived imagery of the landfall of hurricane Harvey reaching almost the size of Texas, August 2017. Image credit from RAMMB / CIRA slider.

Category 3: Devastating damage will occur.

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Hurricane Otto over Nicaragua, Nov 24th, 2016. Image from NASA´s EOSDIS worldview.

Category 2: Extremely dangerous winds.

Hurricane Alex was an unusual hurricane, since was formed in June, was the first tropical cyclone to develop in the 2010 Atlantic hurricane season. Originating from an area of disturbed weather on June 25, 2010, slowly developed in the western Caribbean Sea and struck Belize as a heavy tropical storm. After entering the Gulf of Mexico, Alex became huge and encountered conditions for gradual growth. On June 30, the cyclone reached hurricane status as it approached northeastern Mexico and the storm rapidly intensified just off the coast of Tamaulipas. Alex came ashore near Soto la Marina, Mexico as a Category 2 hurricane. 33 reported fatalities.

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Alex approaching Tamaulipas, Mexico shore, June 2010. Image from MODIS Rapid Response Team.

Category 1: Very dangerous winds.

Hurricane Ophelia was a long-lived storm remembered for its very erratic behavior and extremely slow motion off the East Coast of the United States, alternating several times between tropical storm and hurricane intensity. This hurricane caused some damage and beach erosion along the United States coastline from Florida to North Carolina, with its closest approach occurring on September 14 and 15 with its western eyewall crossing land and the eye remaining just offshore. Minimal damage and erosion was also reported in Atlantic Canada when Ophelia hit as a tropical storm in extratropical transition on September 17 and 18. 1 fatality recorded.

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Ophelia near north Carolina, September 2005. NASA image credit from Jeff Schmaltz, MODIS Land Rapid Response Team at NASA GSFC.
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Author: Jesus Padilla

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