Saffir-Simpson Hurricane Scale
Encyclopedia
The Saffir–Simpson Hurricane Scale (SSHS), or the Saffir–Simpson Hurricane Wind Scale (SSHWS), classifies hurricanes — Western Hemisphere
tropical cyclone
s that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained wind
s. To be classified as a hurricane, a tropical cyclone
must have maximum sustained wind
s of at least 74 mph (33.1 m/s; 60.8 kn) (Category 1). The highest classification in the scale, Category 5, is reserved for storms with winds exceeding 155 mph (69.3 m/s; 127.3 kn).
The classifications can provide some indication of the potential damage and flood
ing a hurricane will cause upon landfall
.
Officially, 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 scales
to label these storms, which are called "cyclones" or "typhoons", depending on the area.
There is occasional criticism of the classifications as being too simple.
Herbert Saffir
and meteorologist Bob Simpson, who at the time was director of the U.S. National Hurricane Center
(NHC). The scale was introduced to the general public in 1973, and saw widespread use after Neil Frank
replaced Simpson at the helm of the NHC in 1974.
The initial scale was developed by Saffir, a structural engineer, who in 1969 went on commission for the United Nations
to study low-cost housing in hurricane-prone areas. While performing 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
in describing earthquakes, he devised a 1–5 scale based on wind speed
that showed expected damage to structures. Saffir gave the scale to the NHC, and Simpson added the effects of storm surge
and flooding.
In 2009, the NHC made moves to eliminate pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale (Experimental) [SSHWS]. The new scale became operational on May 15, 2010. The scale excludes flood ranges, storm surge estimations, rainfall, and location, which means a Category 2 hurricane which hits a major city will likely do far more cumulative damage than a Category 5 hurricane that hits a rural area. The agency cited various hurricanes as reasons for removing the "scientifically inaccurate" information, including Hurricane Katrina
and Hurricane Ike
which both had stronger than estimated storm surge and Hurricane Charley
which had weaker than estimated storm surge.
(WMO), which specifies measuring winds at a height of 33 ft (10.1 m) for 10 minutes, and then taking the average. By contrast, the U.S. National Weather Service
defines sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height. Central pressure
and storm surge values are approximate and often dependant on other factors, such as the size of the storm and the location. Intensity of example hurricanes is from both the time of landfall and the maximum intensity. As a result, it is not uncommon for a pressure to be significantly higher or lower than expected for a specific category. Generally, large storms with very large radii of maximum winds have the lowest pressures relative to its intensity.
The scale is roughly logarithmic in wind speed, and the top wind speed for Category "c" (c=1 to 4) can be expressed as
miles per hour rounded to the nearest multiple of 5.
The five categories are, in order of increasing intensity:
Very dangerous winds will cause some damage
Category 1 storms usually cause no significant structural damage
; however, they can topple unanchored mobile home
s, as well as uproot or snap trees. Poorly attached roof shingles or tiles can blow off. Coastal flooding and pier
damage are often associated with Category 1 storms. Power outages are typically widespread to extensive, sometimes lasting several days. Even though it is the least intense type of hurricane, the storm can still produce plenty of widespread damage and can be a life-threatening storm.
Examples of storms which made landfall at this intensity include: Hurricane Alice (1954), Danny
(1985), Jerry
(1989), Lester
(1992), Ismael
(1995), Claudette
(2003), Humberto
(2007).
Extremely dangerous winds will cause extensive damage
Storms of Category 2 are strong enough to lift a house and inflict damage upon poorly constructed doors and windows. Vegetation
, poorly constructed signs, and piers can receive considerable damage. Mobile homes, whether anchored or not, are typically damaged, and many manufactured homes
also suffer structural damage. Small craft in unprotected anchorages may break their moorings. Extensive to near-total power outages and scattered loss of potable water are likely, possibly lasting many days.
Hurricanes that peaked at Category 2 intensity, and made landfall at that intensity, include Diana
(1990), Erin
(1995), Alma
(1996), Marty
(2003), Juan
(2003), Alex (2010).
Devastating damage will occur
Tropical cyclones of Category 3 and higher are described as major hurricanes in the Atlantic or Eastern Pacific basins
. These storms can cause some structural damage to small residences and utility buildings, particularly those of wood frame or manufactured materials with minor curtainwall failures. Buildings that lack a solid foundation, such as mobile homes, are usually destroyed, and gable
-end roofs are peeled off. Manufactured homes usually sustain severe and irreparable damage. Flooding near the coast destroys smaller structures, while larger structures are struck by float
ing debris. Additionally, terrain
may be flooded well inland. Near-total to total power loss is likely for up to several weeks and water will likely also be lost.
Examples of landfalling storms of this intensity include Carol
(1954), Alma
(1966), Alicia
(1983), Fran
(1996), Isidore
(2002), Jeanne
(2004), Lane
(2006), Karl (2010).
Catastrophic damage will occur
Category 4 hurricanes tend to produce more extensive curtainwall failures, with some complete roof structural failure
on small residences. Heavy, irreparable damage and near complete destruction of gas station canopies and other wide span overhang type structures are common. Mobile and manufactured homes are leveled. These storms cause extensive beach erosion, while terrain may be flooded far inland. Total and long-lived electrical and water losses are to be expected, possibly for many weeks.
The Galveston Hurricane of 1900
, the deadliest natural disaster to hit the United States
, peaked at an intensity that corresponds to a modern-day Category 4 storm. Other examples of storms making landfall at this intensity include Hazel
(1954), Carmen
(1974), Joan (1988), Iniki
(1992), Luis
(1995), Iris
and Michelle
(both in 2001), and Charley
(2004).
Catastrophic damage will occur
Category 5 is the highest category a tropical cyclone can obtain in the Saffir-Simpson scale. These storms cause complete roof failure on many residences and industrial buildings, and some complete building failures with small utility buildings blown over or away. Collapse of many wide-span roofs and walls, especially those with no interior supports, is common. Very heavy and irreparable damage to many wood frame structures and total destruction to mobile/manufactured homes is prevalent. Only a few types of structures are capable of surviving intact, and only if located at least 3 to 5 mi (4.8 to 8 km) inland. They include office, condominium and apartment buildings and hotels that are of solid concrete or steel frame construction, public multi-story concrete parking garages, and residences that are made of either reinforced brick or concrete
/cement
block and have hipped roof
s with slopes of no less than 35 degrees from horizontal and no overhangs of any kind, and if the windows are either made of hurricane resistant safety glass or covered with shutters.
The storm's flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened or washed away by the storm surge. Storm surge damage can occur up to four city blocks inland, with flooding, depending on terrain, reaching six to seven blocks inland. Massive evacuation
of residential areas may be required if the hurricane threatens populated areas. Total and extremely long-lived electrical and water losses are to be expected, possibly for up to several months.
Storms of this intensity can be severely damaging. Historical examples that reached the Category 5 status and made landfall as such, include the 1928 Okeechobee hurricane
, the Labor Day Hurricane of 1935
, the 1959 Mexico Hurricane
, Camille
in 1969, Gilbert
in 1988, Andrew
in 1992, Dean
, and Felix
(both in 2007).
and Lakshmi Kantha, have criticized the scale as being too simplistic, indicating that the scale does not take into account the physical size of a storm, nor the amount of precipitation
it produces. Additionally, they and others point out that the Saffir-Simpson scale, unlike the Richter scale used to measure earthquakes, is not open-ended, and is quantized
into a small number of categories. Proposed replacement classifications include the Hurricane Intensity Index, which is based on the dynamic pressure caused by a storm's winds, and the Hurricane Hazard Index, which bases itself on surface wind speeds, the radius of maximum wind
s of the storm, and its translational
velocity. Both of these scales are continuous, akin to the Richter scale; however, neither of these scales have been used by officials.
, a few newspaper columnists and scientists brought up the suggestion of introducing Category 6, and they have suggested pegging Category 6 to storms with winds greater than 174 or; 150 –. Only a few storms of this category have been recorded, most were West Pacific and titled as super typhoons, most notably Typhoon Tip
in 1979 with sustained winds of 190 mph (305.8 km/h).
According to Robert Simpson, there are no reasons for a Category 6 on the Saffir-Simpson Scale because it is designed to measure the potential damage of a hurricane to manmade structures. If the wind speed of the hurricane is above 155 mph (249.4 km/h), then the damage to a building will be "serious no matter how well it's engineered".
Western Hemisphere
The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the Prime Meridian and east of the Antimeridian , the other half being called the Eastern Hemisphere.In this sense, the western hemisphere consists of the western portions...
tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
s that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
s. To be classified as a hurricane, a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
must have maximum sustained wind
Maximum sustained wind
The maximum sustained winds associated with a tropical cyclone are a common indicator of the intensity of the storm. Within a mature tropical cyclone, they are found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are...
s of at least 74 mph (33.1 m/s; 60.8 kn) (Category 1). The highest classification in the scale, Category 5, is reserved for storms with winds exceeding 155 mph (69.3 m/s; 127.3 kn).
The classifications can provide some indication of the potential damage and flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing a hurricane will cause upon landfall
Landfall (meteorology)
Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...
.
Officially, the Saffir–Simpson Hurricane Scale is used only to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean
Pacific hurricane
A Pacific hurricane or tropical storm is a tropical cyclone that develops in the northeastern part of the Pacific Ocean. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern, , central , and western...
east of the International Date Line
International Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
. Other areas use different scales
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
to label these storms, which are called "cyclones" or "typhoons", depending on the area.
There is occasional criticism of the classifications as being too simple.
History
The scale was developed in 1971 by civil engineerCivil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
Herbert Saffir
Herbert Saffir
Herbert Seymour Saffir was the developer of the Saffir-Simpson Hurricane Scale, for measuring the intensity of hurricanes. As recently as 2005, Saffir was the principal of Saffir Engineering in Coral Gables, Florida...
and meteorologist Bob Simpson, who at the time was director of the U.S. National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
(NHC). The scale was introduced to the general public in 1973, and saw widespread use after Neil Frank
Neil Frank
Dr. Neil Frank, Ph.D. is an American meteorologist and former director of the National Hurricane Center in Florida. He was instrumental in advancing both the scientific and informational aspects of hurricane forecasting. He retired as Chief Meteorologist at KHOU-TV in Houston. Dr...
replaced Simpson at the helm of the NHC in 1974.
The initial scale was developed by Saffir, a structural engineer, who in 1969 went on commission for the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
to study low-cost housing in hurricane-prone areas. While performing 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
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
in describing earthquakes, he devised a 1–5 scale based on wind speed
Wind speed
Wind speed, or wind velocity, is a fundamental atmospheric rate.Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth and metabolism rate of many plant species, and countless other implications....
that showed expected damage to structures. Saffir gave the scale to the NHC, and Simpson added the effects of storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
and flooding.
In 2009, the NHC made moves to eliminate pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale (Experimental) [SSHWS]. The new scale became operational on May 15, 2010. The scale excludes flood ranges, storm surge estimations, rainfall, and location, which means a Category 2 hurricane which hits a major city will likely do far more cumulative damage than a Category 5 hurricane that hits a rural area. The agency cited various hurricanes as reasons for removing the "scientifically inaccurate" information, including Hurricane Katrina
Hurricane Katrina
Hurricane Katrina of the 2005 Atlantic hurricane season was a powerful Atlantic hurricane. It is the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall...
and Hurricane Ike
Hurricane Ike
Hurricane Ike was the second-costliest hurricane ever to make landfall in the United States, the costliest hurricane ever to impact Cuba and the second most active hurricane to reach the Canadian mainland in the Great Lakes Region after Hurricane Hazel in 1954...
which both had stronger than estimated storm surge and Hurricane Charley
Hurricane Charley
Hurricane Charley was the third named storm, the second hurricane, and the second major hurricane of the 2004 Atlantic hurricane season. Charley lasted from August 9 to August 15, and at its peak intensity it attained 150 mph winds, making it a strong Category 4 hurricane on the...
which had weaker than estimated storm surge.
Categories
The scale separates hurricanes into five different categories based on wind. The U.S. National Hurricane Center classifies hurricanes of Category 3 and above as major hurricanes (although all hurricanes can be very dangerous). Most weather agencies use the definition for sustained winds recommended by the World Meteorological OrganizationWorld Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...
(WMO), which specifies measuring winds at a height of 33 ft (10.1 m) for 10 minutes, and then taking the average. By contrast, the U.S. National Weather Service
National Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
defines sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height. Central pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
and storm surge values are approximate and often dependant on other factors, such as the size of the storm and the location. Intensity of example hurricanes is from both the time of landfall and the maximum intensity. As a result, it is not uncommon for a pressure to be significantly higher or lower than expected for a specific category. Generally, large storms with very large radii of maximum winds have the lowest pressures relative to its intensity.
The scale is roughly logarithmic in wind speed, and the top wind speed for Category "c" (c=1 to 4) can be expressed as
miles per hour rounded to the nearest multiple of 5.The five categories are, in order of increasing intensity:
Category 1
| Sustained winds | 33–42 m/s Metre per second Metre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds.... |
64–82 kn |  Hurricane Lester near landfall |
|---|---|---|---|
| 119–153 km/h | 74–95 mph | ||
| Normal central pressure Atmospheric pressure Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point... |
980–994 mbar | 28.94 inHg Inch of mercury Inches of mercury, ' is a unit of measurement for pressure. It is still widely used for barometric pressure in weather reports, refrigeration and aviation in the United States, but is seldom used elsewhere.... |
Very dangerous winds will cause some damage
Category 1 storms usually cause no significant structural damage
Property damage
Property damage is damage to or the destruction of public or private property, caused either by a person who is not its owner or by natural phenomena. Property damage caused by persons is generally categorized by its cause: neglect , and intentional damage...
; however, they can topple unanchored mobile home
Mobile home
Mobile homes or static caravans are prefabricated homes built in factories, rather than on site, and then taken to the place where they will be occupied...
s, as well as uproot or snap trees. Poorly attached roof shingles or tiles can blow off. Coastal flooding and pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...
damage are often associated with Category 1 storms. Power outages are typically widespread to extensive, sometimes lasting several days. Even though it is the least intense type of hurricane, the storm can still produce plenty of widespread damage and can be a life-threatening storm.
Examples of storms which made landfall at this intensity include: Hurricane Alice (1954), Danny
Hurricane Danny (1985)
Hurricane Danny was a minimal Category 1 hurricane on the Saffir-Simpson hurricane scale that made landfall in the U.S. state of Louisiana. The fourth tropical cyclone and third hurricane of the 1985 Atlantic hurricane season, Danny originated from a tropical wave that moved into the western...
(1985), Jerry
Hurricane Jerry (1989)
Hurricane Jerry was the tenth named storm and the sixth and final hurricane of the 1989 Atlantic hurricane season. Jerry was also the fourth U.S. landfalling storm and the third storm to strike Texas during the 1989 season; the two previous storms were Allison in June and Chantal in August. When it...
(1989), Lester
Hurricane Lester (1992)
Hurricane Lester was the first Pacific tropical cyclone to enter the United States as a tropical storm since 1967. The twelfth named storm and seventh hurricane of the 1992 Pacific hurricane season, Lester formed on August 20 from a tropical wave southwest of Mexico. The tropical storm moved...
(1992), Ismael
Hurricane Ismael
Hurricane Ismael was a weak, but deadly Pacific hurricane that killed over one hundred people in northern Mexico in September of the 1995 Pacific hurricane season. It developed from a persistent area of deep convection on September 12, and steadily strengthened as it moved to the north-northwest...
(1995), Claudette
Hurricane Claudette (2003)
Hurricane Claudette was the third tropical storm and first hurricane of the 2003 Atlantic hurricane season. A fairly long-lived July Atlantic hurricane, Claudette began as a tropical wave in the eastern Caribbean. It moved quickly westward, brushing past the Yucatán Peninsula before moving...
(2003), Humberto
Hurricane Humberto (2007)
Hurricane Humberto was a minimal hurricane that formed and intensified faster than any other North Atlantic tropical cyclone on record before landfall. Developing on September 12, 2007, in the northwestern Gulf of Mexico, the tropical cyclone rapidly strengthened and struck High Island, Texas, with...
(2007).
Category 2
| Sustained winds | 43–49 m/s | 83–95 kn | Alex approaching Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... |
|---|---|---|---|
| 154–177 km/h | 96–110 mph | ||
| Normal central pressure | 965–979 mbar | 28.50–28.91 inHg |
Extremely dangerous winds will cause extensive damage
Storms of Category 2 are strong enough to lift a house and inflict damage upon poorly constructed doors and windows. Vegetation
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
, poorly constructed signs, and piers can receive considerable damage. Mobile homes, whether anchored or not, are typically damaged, and many manufactured homes
Manufactured housing
Manufactured housing is a type of prefabricated housing that is largely assembled in factories and then transported to sites of use...
also suffer structural damage. Small craft in unprotected anchorages may break their moorings. Extensive to near-total power outages and scattered loss of potable water are likely, possibly lasting many days.
Hurricanes that peaked at Category 2 intensity, and made landfall at that intensity, include Diana
Hurricane Diana
Hurricane Diana was the deadliest tropical cyclone during the 1990 Atlantic hurricane season, killing 139 people in Mexico. Forming out of a tropical wave on August 4, the system brushed Honduras before intensifying into a tropical storm the following day. Gradually gaining strength, Diana...
(1990), Erin
Hurricane Erin (1995)
Hurricane Erin was the fifth named tropical cyclone and the second hurricane of the unusually active 1995 Atlantic hurricane season. Erin began as a tropical wave off the west coast of Africa on July 22, and crossed the Atlantic ocean without ever developing. On July 31, the last day of the month,...
(1995), Alma
Hurricane Alma (1996)
Hurricane Alma was the first of three consecutively named storms to make landfall on the Pacific coast of Mexico during a ten-day span. Alma was the third tropical cyclone, first named storm and first hurricane of the 1996 Pacific hurricane season. It is believed that the storm originated out of an...
(1996), Marty
Hurricane Marty (2003)
Hurricane Marty was the deadliest tropical cyclone of the 2003 Pacific hurricane season. Forming on September 18, it became the 13th tropical storm and fourth hurricane of the year...
(2003), Juan
Hurricane Juan
Hurricane Juan was a significant hurricane that struck the southern part of Atlantic Canada in late September 2003. It was the tenth named storm and the sixth hurricane of the 2003 Atlantic hurricane season. Juan formed southeast of Bermuda on September 24, 2003 out of a tropical wave that tracked...
(2003), Alex (2010).
Category 3
| Sustained winds | 50–58 m/s | 96–113 kn |  Roxanne Hurricane Roxanne Hurricane Roxanne caused extensive flooding in Mexico due to its erratic movement. The seventeenth storm, tenth hurricane, and the fifth and final major hurricane of the very active 1995 Atlantic hurricane season, Roxanne developed in the southwestern Caribbean Sea from an area of low pressure on... near its peak strength |
|---|---|---|---|
| 178–209 km/h | 111–130 mph | ||
| Normal central pressure | 945–964 mbar | 27.91–28.47 inHg |
Devastating damage will occur
Tropical cyclones of Category 3 and higher are described as major hurricanes in the Atlantic or Eastern Pacific basins
Tropical cyclone basins
Traditionally, areas of tropical cyclone formation are divided into seven basins. These include the north Atlantic Ocean, the eastern and western parts of the northern Pacific Ocean, the southwestern Pacific, the southwestern and southeastern Indian Oceans, and the northern Indian Ocean. The...
. These storms can cause some structural damage to small residences and utility buildings, particularly those of wood frame or manufactured materials with minor curtainwall failures. Buildings that lack a solid foundation, such as mobile homes, are usually destroyed, and gable
Gable
A gable is the generally triangular portion of a wall between the edges of a sloping roof. The shape of the gable and how it is detailed depends on the structural system being used and aesthetic concerns. Thus the type of roof enclosing the volume dictates the shape of the gable...
-end roofs are peeled off. Manufactured homes usually sustain severe and irreparable damage. Flooding near the coast destroys smaller structures, while larger structures are struck by float
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
ing debris. Additionally, terrain
Terrain
Terrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used...
may be flooded well inland. Near-total to total power loss is likely for up to several weeks and water will likely also be lost.
Examples of landfalling storms of this intensity include Carol
Hurricane Carol
Hurricane Carol was among the worst tropical cyclones to affect the New England region of the United States. It developed from a tropical wave near the Bahamas on August 25, 1954, and gradually strengthened as it moved northwestward. On August 27, Carol intensified to reach winds of , but weakened...
(1954), Alma
Hurricane Alma (1966)
Hurricane Alma was a rare June major hurricane in the 1966 Atlantic hurricane season. It was the earliest continental U.S. hurricane strike within any season since 1908...
(1966), Alicia
Hurricane Alicia
Hurricane Alicia was the costliest tropical cyclone in the Atlantic since Hurricane Agnes in 1972. Alicia was the third depression, the first tropical storm, and the only major hurricane of the 1983 Atlantic hurricane season...
(1983), Fran
Hurricane Fran
Hurricane Fran was a powerful Cape Verde-type hurricane of the 1996 Atlantic hurricane season that made landfall near Cape Fear in North Carolina at Category 3 strength. Throughout the eastern United States, early statistics on Fran reported 27 deaths and $3.2 billion in damage...
(1996), Isidore
Hurricane Isidore
Hurricane Isidore was the ninth named storm and the second hurricane in the 2002 Atlantic hurricane season. Isidore was the fifth of eight named storms to occur in September. The tropical cyclone peaked as a Category 3 hurricane, causing damage as well as four fatalities in Jamaica, Cuba, Mexico,...
(2002), Jeanne
Hurricane Jeanne
Hurricane Jeanne was the deadliest hurricane in the 2004 Atlantic hurricane season. It was the tenth named storm, the seventh hurricane, and the fifth major hurricane of the season, as well as the third hurricane and fourth named storm of the season to make landfall in Florida...
(2004), Lane
Hurricane Lane (2006)
Hurricane Lane was the thirteenth named storm, ninth hurricane, and sixth major hurricane of the 2006 Pacific hurricane season. The strongest Pacific hurricane to make landfall in Mexico since Hurricane Kenna of 2002, Lane developed on September 13 from a tropical wave to the south of Mexico...
(2006), Karl (2010).
Category 4
| Sustained winds | 59–69 m/s | 114–135 kn | Joan at peak intensity over Nicaragua |
|---|---|---|---|
| 210–249 km/h | 131–155 mph | ||
| Normal central pressure | 920–944 mbar | 27.17–27.88 inHg |
Catastrophic damage will occur
Category 4 hurricanes tend to produce more extensive curtainwall failures, with some complete roof structural failure
Structural failure
Structural failure refers to loss of the load-carrying capacity of a component or member within a structure or of the structure itself. Structural failure is initiated when the material is stressed to its strength limit, thus causing fracture or excessive deformations...
on small residences. Heavy, irreparable damage and near complete destruction of gas station canopies and other wide span overhang type structures are common. Mobile and manufactured homes are leveled. These storms cause extensive beach erosion, while terrain may be flooded far inland. Total and long-lived electrical and water losses are to be expected, possibly for many weeks.
The Galveston Hurricane of 1900
Galveston Hurricane of 1900
The Hurricane of 1900 made landfall on the city of Galveston in the U.S. state of Texas, on September 8, 1900.It had estimated winds of at landfall, making it a Category 4 storm on the Saffir-Simpson Hurricane Scale...
, the deadliest natural disaster to hit the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, peaked at an intensity that corresponds to a modern-day Category 4 storm. Other examples of storms making landfall at this intensity include Hazel
Hurricane Hazel
Hurricane Hazel was the deadliest and costliest hurricane of the 1954 Atlantic hurricane season. The storm killed as many as 1,000 people in Haiti before striking the United States near the border between North and South Carolina, as a Category 4 hurricane...
(1954), Carmen
Hurricane Carmen
Hurricane Carmen was the most intense tropical cyclone of the 1974 Atlantic hurricane season. A destructive and widespread storm, Carmen originated as a tropical disturbance that emerged from Africa toward the end of August. The wave traveled westward, spawning a tropical depression east of the...
(1974), Joan (1988), Iniki
Hurricane Iniki
Hurricane Iniki was the most powerful hurricane to strike the U.S. state of Hawaii in recorded history. Forming on September 5 during the strong El Niño of 1991–1994, Iniki was one of eleven Central Pacific tropical cyclones during the 1992 season. It attained tropical storm status on...
(1992), Luis
Hurricane Luis
Hurricane Luis was one of the deadliest and most destructive hurricanes of the 1995 Atlantic hurricane season, with maximum sustained winds of 140 mph . The storm was the twelfth tropical storm, sixth hurricane, and second major hurricane of the season...
(1995), Iris
Hurricane Iris
Hurricane Iris was a Category 4 hurricane that devastated Belize in October 2001. It was the eleventh tropical cyclone, ninth named storm, fifth hurricane, and third major hurricane of the 2001 Atlantic hurricane season. It was the second strongest storm of the season behind Hurricane...
and Michelle
Hurricane Michelle
Hurricane Michelle was the thirteenth named storm and the strongest tropical cyclone of the 2001 Atlantic hurricane season. Michelle developed from a tropical wave that moved across the Atlantic, and formed into Tropical Depression Fifteen on the October 29. The depression slowly intensified as...
(both in 2001), and Charley
Hurricane Charley
Hurricane Charley was the third named storm, the second hurricane, and the second major hurricane of the 2004 Atlantic hurricane season. Charley lasted from August 9 to August 15, and at its peak intensity it attained 150 mph winds, making it a strong Category 4 hurricane on the...
(2004).
Category 5
| Sustained winds | ≥ 70 m/s | ≥ 136 kn | John Hurricane John (1994) Hurricane John formed during the 1994 Pacific hurricane season and became both the longest-lasting and the farthest-traveling tropical cyclone ever observed... in the central Pacific Ocean Pacific Ocean The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World... |
|---|---|---|---|
| ≥ 250 km/h | ≥ 156 mph | ||
| Normal central pressure | < 920 mbar | < 27.17 inHg |
Catastrophic damage will occur
Category 5 is the highest category a tropical cyclone can obtain in the Saffir-Simpson scale. These storms cause complete roof failure on many residences and industrial buildings, and some complete building failures with small utility buildings blown over or away. Collapse of many wide-span roofs and walls, especially those with no interior supports, is common. Very heavy and irreparable damage to many wood frame structures and total destruction to mobile/manufactured homes is prevalent. Only a few types of structures are capable of surviving intact, and only if located at least 3 to 5 mi (4.8 to 8 km) inland. They include office, condominium and apartment buildings and hotels that are of solid concrete or steel frame construction, public multi-story concrete parking garages, and residences that are made of either reinforced brick or concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
/cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
block and have hipped roof
Hip roof
A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid. Hip roofs on the houses could have two triangular side...
s with slopes of no less than 35 degrees from horizontal and no overhangs of any kind, and if the windows are either made of hurricane resistant safety glass or covered with shutters.
The storm's flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened or washed away by the storm surge. Storm surge damage can occur up to four city blocks inland, with flooding, depending on terrain, reaching six to seven blocks inland. Massive evacuation
Emergency evacuation
Emergency evacuation is the immediate and rapid movement of people away from the threat or actual occurrence of a hazard. Examples range from the small scale evacuation of a building due to a bomb threat or fire to the large scale evacuation of a district because of a flood, bombardment or...
of residential areas may be required if the hurricane threatens populated areas. Total and extremely long-lived electrical and water losses are to be expected, possibly for up to several months.
Storms of this intensity can be severely damaging. Historical examples that reached the Category 5 status and made landfall as such, include the 1928 Okeechobee hurricane
1928 Okeechobee Hurricane
The Okeechobee hurricane, or San Felipe Segundo hurricane, was a deadly hurricane that struck the Leeward Islands, Puerto Rico, the Bahamas, and Florida in September of the 1928 Atlantic hurricane season...
, the Labor Day Hurricane of 1935
Labor Day Hurricane of 1935
The 1935 Labor Day Hurricane was the strongest tropical cyclone of the 1935 Atlantic hurricane season, and one of the most intense hurricanes to make landfall in the United States in recorded history...
, the 1959 Mexico Hurricane
1959 Mexico Hurricane
The 1959 Mexico Hurricane was a devastating tropical cyclone that was one of the worst ever Pacific hurricanes. It impacted the Pacific coast of Mexico in October 1959. It killed at least 1,000 people, and perhaps double that, a record that still stands, and caused at least 280 million...
, Camille
Hurricane Camille
Hurricane Camille was the third and strongest tropical cyclone and second hurricane during the 1969 Atlantic hurricane season. The second of three catastrophic Category 5 hurricanes to make landfall in the United States during the 20th century , which it did near the mouth of the Mississippi River...
in 1969, Gilbert
Hurricane Gilbert
Hurricane Gilbert was an extremely powerful Cape Verde-type hurricane that formed during the 1988 Atlantic hurricane season and created widespread destruction in the Caribbean Sea and the Gulf of Mexico. It is the second most intense hurricane ever observed in the Atlantic basin behind only...
in 1988, Andrew
Hurricane Andrew
Hurricane Andrew was the third Category 5 hurricane to make landfall in the United States, after the Labor Day Hurricane of 1935 and Hurricane Camille in 1969. Andrew was the first named storm and only major hurricane of the otherwise inactive 1992 Atlantic hurricane season...
in 1992, Dean
Hurricane Dean
The name Dean was used for five tropical cyclones in the Northern Atlantic Ocean:*1983's Tropical Storm Dean, which struck the coast of Virginia, causing minor erosion and flooding...
, and Felix
Hurricane Felix
The name Felix was used for four tropical cyclones in the Atlantic Ocean.* 1989's Hurricane Felix - A Category 1 storm that dissipated in the Atlantic without threatening land....
(both in 2007).
Criticism
Some scientists, including Kerry EmanuelKerry Emanuel
Kerry Emanuel is an American professor of meteorology currently working at the Massachusetts Institute of Technology in Cambridge. In particular he has specialized in atmospheric convection and the mechanisms acting to intensify hurricanes. He coined the term "hypercane" in 1994. In 2007, he was...
and Lakshmi Kantha, have criticized the scale as being too simplistic, indicating that the scale does not take into account the physical size of a storm, nor the amount of precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
it produces. Additionally, they and others point out that the Saffir-Simpson scale, unlike the Richter scale used to measure earthquakes, is not open-ended, and is quantized
Quantization (signal processing)
Quantization, in mathematics and digital signal processing, is the process of mapping a large set of input values to a smaller set – such as rounding values to some unit of precision. A device or algorithmic function that performs quantization is called a quantizer. The error introduced by...
into a small number of categories. Proposed replacement classifications include the Hurricane Intensity Index, which is based on the dynamic pressure caused by a storm's winds, and the Hurricane Hazard Index, which bases itself on surface wind speeds, the radius of maximum wind
Radius of maximum wind
The radius of maximum wind is the distance between the center of a cyclone and its band of strongest winds. It is a parameter in atmospheric dynamics and tropical cyclone forecasting. The highest rainfall rates occur near the RMW of tropical cyclones. The extent of a cyclone's storm surge and...
s of the storm, and its translational
Translation (geometry)
In Euclidean geometry, a translation moves every point a constant distance in a specified direction. A translation can be described as a rigid motion, other rigid motions include rotations and reflections. A translation can also be interpreted as the addition of a constant vector to every point, or...
velocity. Both of these scales are continuous, akin to the Richter scale; however, neither of these scales have been used by officials.
Category 6
After the series of powerful storm systems of the 2005 Atlantic hurricane season2005 Atlantic hurricane season
The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...
, a few newspaper columnists and scientists brought up the suggestion of introducing Category 6, and they have suggested pegging Category 6 to storms with winds greater than 174 or; 150 –. Only a few storms of this category have been recorded, most were West Pacific and titled as super typhoons, most notably Typhoon Tip
Typhoon Tip
Typhoon Tip was the largest and most intense tropical cyclone on record. The nineteenth tropical storm and twelfth typhoon of the 1979 Pacific typhoon season, Tip developed out of a disturbance in the monsoon trough on October 4 near Pohnpei...
in 1979 with sustained winds of 190 mph (305.8 km/h).
According to Robert Simpson, there are no reasons for a Category 6 on the Saffir-Simpson Scale because it is designed to measure the potential damage of a hurricane to manmade structures. If the wind speed of the hurricane is above 155 mph (249.4 km/h), then the damage to a building will be "serious no matter how well it's engineered".
See also
- Tropical cyclone scalesTropical cyclone scalesTropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
- Beaufort scaleBeaufort scaleThe Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort Wind Force Scale.-History:...
- Fujita scaleFujita scaleThe Fujita scale , or Fujita-Pearson scale, is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation...
– For tornado intensity with damage correlated to wind speeds. The system was also intended for applicability in hurricanes, and is utilized by engineers in hurricane damage assessment. - Rohn Emergency ScaleRohn Emergency ScaleThe Rohn Emergency Scale is a scale on which the magnitude of an emergency is measured. It was first proposed in 2006, and explained in more detail in a peer-reviewed paper presented at a 2007 system sciences conference. The idea was further refined later that year. The need for such a scale was...
for measuring the magnitude (intensity) of any emergency - Severe weather terminologySevere weather terminology (United States)This article describes the United States National Weather Service severe weather terminology. The NWS defines precise meanings for nearly all its weather terms. This article describes NWS terminology and related NWS weather scales...
- List of tropical cyclones
- List of Category 5 Atlantic hurricanes
- List of Category 5 Pacific hurricanes
External links
- An Interview with Dr. Robert Simpson — The Mariners Weather Log, April 1999
- Q&A with Herbert Saffir — The South Florida Sun-Sentinel, June 2001