The Saffir-Simpson Hurricane Scale is used to classify storms that are stronger than “tropical depressions” and “tropical storms”. The scale separates hurricanes into five different categories based on sustained wind speeds, barometric pressure, and storm surge. In order to be classified as a hurricane, a storm must have sustained winds of more than 74 mph. The highest classification in the scale, Category 5, is reserved for storms with winds greater than 155 mph. The U.S. National Hurricane Center classifies hurricanes of Category 3 and above as major hurricanes.
The classifications are intended primarily for use in measuring the potential damage and flooding a hurricane will cause upon landfall. The Saffir-Simpson Hurricane Scale is used only to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas use different classification scales to classify storms, which are called “cyclones” or “typhoons”, depending on the area.
Saffir-Simpson Scale History
The Saffir-Simpson Hurricane Wind Scale was developed in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson.
The initial scale was developed by Saffir, a structural engineer, who in 1969 was commissioned by the United Nations to study low-cost housing in hurricane-prone areas. While conducting the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. Mirroring the utility of the Richter magnitude scale for describing earthquakes, he devised a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the National Hurricane Center, and Robert Simpson who the director of the U.S. National Hurricane Center at the time, added the effects of storm surge and flooding.
Sustained Winds: 74-95 mph
Very dangerous winds will produce some damage
Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.
Even though it is the least intense type of hurricane, they can still produce widespread damage and can be life-threatening storms.
Hurricane Barry in 2019 and Hurricane Isaias in 2020 made landfall as Category 1 hurricanes.
Sustained Winds: 96-110 mph
Extremely dangerous winds will cause extensive damage
Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.
Hurricane Sally that struck Alabama in September 2020 was a Category 2 storm.
Sustained Winds: 111-129 mph
Devastating damage will occur
Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.
Tropical cyclones of Category 3 and higher are described as major hurricanes in the Atlantic or Eastern Pacific basins.
Sustained Winds: 130-156 mph
Catastrophic damage will occur
Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
Hurricane Harvey that flooded Houston, Texas in 2017 was a Category 4 storm.
There were three storms rated as Category 4 in 2020: Laura, Eta and Iota.
Sustained Winds: 157 mph or higher
Catastrophic damage will occur
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.
Category 5 is the highest category of the Saffir–Simpson scale.
Historical examples of storms that made landfall at Category 5 status include: Camille in 1969, Andrew that struck South Florida in 1992, Katrina in 2005 and Michael in 2018.
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Background Picture: Hurricane Dean on August 18, 2007 at approximately 1409 UTC. This image was produced from data from MetOp-2/A, provided by NOAA. (U.S. National Oceanic and Atmospheric Administration)