Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
Congressional testimony by Max Mayfield, Director of the National Hurricane Center, and comments by Dr. William Gray of Colorado State Univerity following Hurricane Katrina have drawn attention to the research on heightened states of activity in the Atlantic basin. Many climatologists believe that hurricane activity in the Atlantic Ocean may be on the rise. This increase, driven by two main causes (see Appendix A), has led to growing concern amongst the research community about a frequency shift that has occurred over the last 10 years for Atlantic tropical systems. Additionally, 2004 and 2005 proved to be a very challenging period for insurers and reinsurers, as these active hurricane seasons forced companies to cope with record high damage claims numbers in Louisiana, Mississippi, Alabama and Florida. Climatological experts have said that the Atlantic and Caribbean Oceans are currently in an heightened period of hurricane activity, and that this activity increase may continue for another 1 to 2 decades (see Appendix A). Latest trends and occurrences are all evidence that hurricanes may be more destructive due to an increase in intensity, duration and coastal property exposure.
The limited reliable historical record of hurricane reporting shows a great deal of variation for short periods of time when large numbers of storms have occurred in a given year and intense storms have occurred in another year (see Appendix B).
For example, in the period between 1970 and 1994, hurricane frequencies and intensities were weaker than average. Since
1995, hurricane destructiveness appears to be increasing beyond the long-term average. This effect is explained by extensive urban development occurring along the coastlines of the United States combined with increased hurricane occurrences.
Impact Forecasting has studied this upswing in hurricane frequency and destructiveness in the Atlantic Basin and has assigned factors for different classes of hurricanes and exposed regions of the East and Gulf Coasts to take into account an increase in frequency. The hurricane landfall regions of the United States were divided up into four main regions for frequency considerations: (1) The Gulf Coast from Brownsville, Texas to the Florida Peninsula; (2) The west coast of Florida from the Florida Panhandle to the Florida Keys; (3) The east coast of Florida from the Florida Keys to the Florida/South
Carolina border; and (4) the remaining East Coast from South Carolina to Maine. These regions are shown in the map below.
An analysis of cyclone activity was based on historical hurricane data (HURDAT) provided by the National Oceanic and
Atmospheric Administration (NOAA). To enhance the quality and accuracy of the analysis, the time window was limited to
1950 to present due to accuracy of the data (see Appendix C). The historical catalog was separated into “warm” and “cool” periods. These classifications are: (a) warm phase, spanning from 1950 to 1970; (b) cool phase, starting in 1971 and continuing through 1994; and (c) the current warm phase, starting in 1995 to the present. The historical tracks were analyzed for those storms either directly striking land or bypassing the coast. The upward trends indicate the increase in activity in
1950s and again in the last ten years. A linear long-term analysis of this data indicates an average increase of one hurricane every 50 years.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
In order to estimate the hurricane activity in the active and inactive periods, the data was separated into two regimes above and below the average trend line. Assuming that an average of 5.9 hurricanes occur in a normal year, the analysis shows an average of 7 hurricanes per year occur during active periods and an average of 4.7 hurricanes per year occur during inactive periods. The standard deviation for the active periods is 1.91 hurricanes per year, while the standard deviation for the inactive periods is 1.41 hurricanes per year.
The tables below show the frequency ratios devised for the Atlantic Basin for different storm categories using Atlantic Basin hurricane data going back to 1950 and through 2005*. The Active/Mean row depicts the ratio of frequencies for active to long-term period activity for different hurricane categories, while the Inactive/Mean row shows the same information for inactive to long-term period activity. The frequency ratios are derived from applying the overall basin frequencies for each regime to the conditional annual frequency of occurrence of each storm category.
REGION 1: TEXAS TO FLORIDA PANHANDLE (1950-2005 data)
Saffir-Simpson Category
Active/Mean Ratio*
Inactive/Mean Ratio*
3, 4 & 5 All
1 & 2
(Major) Hurricanes
1.15x 1.19x 1.17x
0.88x 0.77x 0.83x
REGION 2: FLORIDA WEST COAST(1950-2005 data)
Saffir-Simpson Category
Active/Mean Ratio *
Inactive/Mean Ratio *
REGION 3: FLORIDA EAST COAST(1950-2005 data)
Saffir-Simpson Category
Active/Mean Ratio *
Inactive/Mean Ratio *
1 & 2
3, 4 & 5
(Major)
All
Hurricanes
1.27x 1.26x 1.27x
0.68x 0.79x 0.72x
3, 4 & 5 All
1 & 2
(Major) Hurricanes
1.22x 1.47x 1.33x
0.73x 0.44x 0.60x
REGION 4: U.S. EAST COAST(1950-2005 data)
Saffir-Simpson Category
Active/Mean Ratio *
Inactive/Mean Ratio *
ALL U.S. COASTAL AREAS (1950-2005 data)
Saffir-Simpson Category
Active/Mean Ratio *
Inactive/Mean Ratio *
1 & 2
3, 4 & 5
(Major)
All
Hurricanes
1.18x 1.47x 1.24x
0.78x 0.44x 0.71x
3, 4 & 5 All
1 & 2
(Major) Hurricanes
1.21x 1.35x 1.28x
0.77x 0.61x 0.69x
* These values actually represent an averaged mean value, therefore exact values could differ from the values reported above to one standard deviation due to differences in each hurricane season.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
There are two main concerns with the increased hurricane activity in the Atlantic basin: (1) long-term effects of the multi-decadal oscillation, and (2) periodic effects of El Nino and La Nina.
CAUSE #1: THE THERMOHALINE CIRCULATION AND THE ATLANTIC MULTI-DECADAL
OSCILLATION
There are three main processes that make the oceans circulate: tidal forces, wind stress, and density differences. The density of seawater is controlled by its temperature (thermo-) and its salinity (-haline), and the circulation driven by density differences is thus called the Thermohaline Circulation . The Thermohaline Circulation, which could be described simply as a global conveyor belt, is driven primarily by the formation and sinking of deep water in the Norwegian Sea, which is graphically depicted below.
This circulation is thought to be responsible for the large flow of upper ocean water from the tropical Pacific to the Indian
Ocean through the Indonesian Archipelogo. The waters are transported from the Indian Ocean into the tropical Atlantic
Ocean, where warming sea surface temperatures occur. The water is then forced northward into the Norwegian Sea, where it sinks into the far depths of the ocean. The flow circuit of the THC is then closed by the formation of North Atlantic Deep
Water (NADW), a range of dense water masses being transformed in the Labrador and Norwegian Seas, adjacent to the
North Atlantic, which is then transported and upwelled again in the northern Pacific Ocean hundreds of years later. Two main counteracting forces operating in the North Atlantic control the conveyor belt circulation:
1. Thermal forcing, which is the flow and exchange of waters to high-latitude cool areas from low-latitude warm areas, drives warm waters northward into the Arctic regions, only to cool and sink into the depths of the ocean and return along the bottom of the sea floor as cold water from the polar regions.
2. Haline forcing, which forces freshwater in high-latitude regions southward into more salty low-latitude regions.
This forcing forces the more fresh waters from melting ice caps and runoff from precipitation in the northern regions to flow to more dense salty waters in the south (evaporation enhances salinity).
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
Currently in the Atlantic Ocean, the thermal forcing of the Thermohaline Circulation is the more dominant force, i.e. the current flowing northward is more dominant than the current flowing south. Thus, warmer waters are making their way northward in the Atlantic Ocean. However, when the strength of the haline forcing increases due to excess precipitation, runoff, or ice melt the conveyor belt will weaken or even shut down. The variability in the strength of this circulation will lead to climate change in Europe and it could also influence in other areas of the global ocean.
The strength and phase of the Thermohaline Circulation drive the Atlantic Multi-Decadal Oscillation (AMO), an oscillation that is used to denote the changes in sea surface temperatures in the Atlantic Ocean over a period of decades. The Atlantic
Multi-Decadal Oscillation is defined as an ongoing series of long-duration changes in the sea surface temperature of the North
Atlantic Ocean, with cool and warm phases that may last for 15 to 40 years at a time and a difference of about 1°F between extremes. These changes are natural and have been occurring for at least the last 1,000 years. The graph below shows the
AMO Index, which basically represents the annual ocean temperature anomalies averaged across the North Atlantic Ocean
(0°-70°N latitude). It shows explicitly that there is a pattern and cycle that the Thermohaline Circulation and Atlantic Multi-
Decadal Oscillation go through.
The above graph clearly shows that there were warmer than normal sea surface temperatures across the whole of the Atlantic
Ocean starting in the early 1930s and continuing into the middle 1960s. After the mid-1960s, however, the Atlantic Ocean went into a cool cycle, when sea surface temperatures were slightly cooler than normal. By the middle of the 1990s, a rapid warming occurred across the Atlantic Ocean. These periods of warmer and cooler sea surface temperatures coincide nicely with active and inactive periods of hurricane activity across the Atlantic Ocean. From the 1930s through the middle 1960s, hurricane frequency was above average across the tropical areas of the Atlantic and into the Caribbean Sea. Starting in the mid-1960s, though, a quiet period started and annual hurricane frequencies dropped significantly. The 1990s signaled an active period once again, with the last several years setting records for the most tropical storms and hurricanes ever in any given year.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
When comparing the AMO Index’s trendline with the 1950-2005 Atlantic Hurricane frequency trendline, striking similarities appear.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
CAUSE #2: THE EL NIÑO/SOUTHERN OSCILLATION CYCLE
The earth is made up of more than 35 different ocean currents. Individual ocean currents, which are shown in the graphic below, are linked to other currents, which work together to make up an ocean oscillation. Each ocean has its own set of driving currents and oscillations, which affect local and global meteorological and climatic effects. However, all of the oscillations are linked together and affect one another when one changes.
Though the graphic above is only a two-dimensional view of the entire ocean oscillation system, the oscillations circulate in a vertical plane as well, with colder waters flowing along bottom of the ocean floor, while warmer waters flow mainly on the surface due to its weight and proximity to sunlight. This 3-dimensional system brings warmer waters to the cooler regions of the ocean system and circulates colder deep waters up to the surface for oxygen replenishing. The ocean currents shown above make up four main ocean oscillations: the Pacific Decadal Oscillation (PDO), the Atlantic Multi-Decadal Oscillation
(AMO), the Quasi-Biennial Oscillation (QBO) and the El Niño/Southern Oscillation (ENSO).
The El Niño/Southern Oscillation refers to a shift in surface air pressure at Darwin, Australia and the South Pacific Island of
Tahiti. When the pressure is high at Darwin, it is low at Tahiti and vice versa. El Niño and its sister event, La Niña, are the extreme phases of these pressure swings, which cause warming and cooling of the central and eastern Pacific Ocean waters.
El Niño referring to a warming of the eastern tropical Pacific, La Niña a cooling of these waters, and neutral conditions when waters are near normal temperature levels. A diagram of these processes is shown below.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
El Niño is defined as a warming of the sea surface temperatures of at least 0.5°C above normal in the region bound by 4°N to 4°S latitude and 150°W to 90°W longitude for more than five consecutive months. This warm phase of the oscillation typically occurs once every three to seven years. During an El Niño period, the trade winds that blow across the Pacific equatorial region relax or, in more extreme cases, change direction. In other words, the normal east-towest direction of the wind may disappear and even change direction to west-to-east. This relaxation or change in the winds causes sea surface temperatures in the central Pacific
Ocean to rise to above normal readings for a period of time, normally about a year. The water temperature alterations allow jet stream patterns to become oriented differently across the Pacific and Atlantic Oceans. As the winds in the
Pacific lessen, the opposite effect is experienced in the
Atlantic. An increase in upper level winds from the west to east prohibit thunderstorms from becoming too tall and disrupt tropical disturbance formation. El Niño conditions in the central Pacific Ocean typically form during the Northern Hemisphere’s summer months, peak during the late fall, and start to dissipate by late spring of the following year.
El Niño’s counterpart, La Niña, is El Niño’s natural opposite.
Thus, La Niña is a cooling of the sea surface temperatures of at least 0.5°C below normal in the region bound by 4°N to
4°S latitude and 150°W to 90°W longitude for more than five consecutive months starting before September and continuing through December. In this event, the trade winds, which typically blow from east to west, strengthen, thus promoting upwelling of the deep ocean waters along the South America coast. These waters then spread into the central Pacific
Ocean and cool the entire region. A La Niña period can last as long as a typical El Niño, though it typically occurs less frequently than El Niño does. The cooler waters in the central Pacific affect the upper level wind pattern, bringing the jet stream further south into the region as well as an increase in upper level wind shear. In the Atlantic, the jet stream pattern shifts northward, which brings the upper level
Bermuda high pressure cell across the majority of the
Atlantic Ocean, promoting low wind shear conditions, which allows thunderstorms to form and strengthen. As these thunderstorms root themselves about a common low pressure area, a tropical disturbance develops.
Statistically speaking, El Niño and La Niña events have altered numerous hurricane season frequencies. The average mean number for all hurricanes (Category 1 through 5) making landfall along the United States coastline during neutral conditions
(normal) is 1.61. In El Niño periods, this mean number is reduced to 1.04, while in La Niña periods the mean number increases up to 2.23. The probability of two or more hurricanes making landfall during a neutral period is 48%, during an El
Niño period is 28%, and during a La Niña period is 66%. When considering only major hurricanes (Category 3 or above) making landfall in the United States, the neutral average mean number is 0.68, the El Niño average mean drops to 0.23, but the La Niña average mean jumps up to 0.95. Probabilities for at least one major hurricane making landfall are 58% for neutral periods, 23% for El Niño periods, and 63% for La Niña periods. During the last 105 years, no El Niño period produced more than one major landfalling hurricane for the United States.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
Upon surveying the hurricane frequency from the last 15 years, there is a definite correlation that exists between the number of tropical systems in the Atlantic and eastern Pacific Oceans and the stage that the El Niño/Southern Oscillation is in. The graph below shows the periods in which El Niño and La Niña conditions were observed superimposed on the number of
Atlantic and eastern Pacific hurricanes per year from 1990 through 2005.
The graph shows an inverse relationship in most cases between the Atlantic and Pacific Oceans and whether an El Niño cycle is in progress or a La Niña cycle is occurring. For example, in the 1992 Hurricane Season, the Atlantic showed a relative neutral below normal pattern, while the Pacific Ocean responded with a higher activity rate. On the other hand, the La Niña period in 1995 and 1996 showed increased activity from prior years in the Atlantic tropical basin, while the eastern Pacific
Ocean showed a fairly drastic decrease in hurricane activity from the prior three years.
The El Niño/Southern Oscillation can bring annual fluctuations to hurricane frequency in the Atlantic and eastern Pacific
Oceans. However, this variable does not fully explain why there has been an overall upswing in hurricane development in the
Atlantic Ocean since 1995 and an overall decrease in the eastern Pacific Ocean since the early 1990s. To explain this, a focus on the Atlantic Ocean is needed.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift
Within the last 55 years of hurricane occurrences, three phases of hurricane frequency have emerged. Upon reviewing historical yearly data, a heightened state of hurricane frequency was in effect during the 1950s into the
1960s. However, coastal building stock was not at the level it is currently.
Therefore, even the most damaging hurricanes did not produce the amount of devastation that has been experienced during 2004 and 2005. By the 1970s and continuing into the early
1990s, hurricane activity returned to a more normal state, and in some years was below the long-term frequency average. The quieter period lasted through 1994. During this time, however, several very destructive storms made landfall in the United
States, including 1992’s Hurricane
Andrew. A very abrupt shift in hurricane frequency occurred in 1995, when the Atlantic and Caribbean
Oceans suddenly became very active.
This state continues currently. The last two states – the quiet period and the current active period – are depicted vividly when analyzing the hurricane data over the last 20 years, as shown in the graphics here.
The following pages in this section detail the higher and lower frequency periods in hurricane activity in the
Atlantic and Caribbean Oceans as well as some of the notable storms that developed during each period.
Reinsurance Services
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
The 1950s and early 1960s were an active period (warm phase) for tropical system activity. Several notable storms occurred during this timeframe, including 1954’s
Hurricane Carol (landfall: eastern Connecticut, 100 mph sustained winds), 1960’s Hurricane Donna (landfall: southern Florida, 135 mph sustained winds), 1961’s
Hurricane Carla (landfall: southeast Texas, 165 mph sustained winds), and 1965’s Hurricane Betsy (landfall: southeast Louisiana, 155 mph sustained winds). The second half of the 1960s started a general decrease in overall tropical system activity, with the exception of the very active year in 1969, spawning a total of 12 hurricanes. One of these 12 hurricanes, Camille, brought massive destruction to an area that would again be destroyed by a powerful hurricane some 36 years later.
The 1970s and 1980s were a relatively quiet time (cool phase) for hurricane activity, though there were periodic years of increased activity and some notable storms.
1974’s Hurricane Carmen slammed Morgan City,
Louisiana with 150 mph sustained winds and caused $620 million (2005 USD) in total losses. In 1979, Hurricane
Frederic roared ashore near Mobile, Alabama with 132 mph sustained winds, causing $4 to $8 billion (2005 USD) in total damages. Southeast Texas incurred $3.8 billion
(2005 USD) in economic losses when Alicia roared ashore near Galveston in 1983 with 115 mph sustained winds. In
1985, Hurricane Gloria made a swipe at the North Carolina
Outer Banks and moved rapidly north into Long Island,
New York with sustained winds of 100 mph. Gloria caused $1.6 billion (2005 USD) in total loss. To round out the 1980s, Hurricane Hugo, one of the most powerful storms on record, slammed South Carolina with 140 mph sustained winds in 1989, causing upwards of $16 to $18 billion
(2005 USD) in economic losses.
The early 1990s, on the average, were below normal for tropical system development. 1990 was substantially above normal, with a total of 14 named storms and
8 hurricanes (normal is 10 and 6, respectively). After 1990, however, the next four years would be below normal for the number of tropical systems and hurricanes.
However, the costliest hurricane in history up to 2005 occurred in 1992, when
Hurricane Andrew annihilated southern
Florida and slammed Louisiana. Andrew, a very small hurricane, brought sustained winds of 165 mph to southern Florida and sustained winds of 140 mph to southeast
Louisiana. Andrew caused $20 billion (2005 USD) in insured losses and $45 billion (2005 USD) in economic losses.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

- 1992
Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
1995 started a period of substantially more tropical systems and hurricanes in the Atlantic Basin. In 1994, there were a total of 7 named storms, 3 hurricanes and no major hurricanes (Category 3 or higher on the Saffir-Simpson Scale). In 1995, a total of 19 named storms (190% of normal), 11 hurricanes (185% of normal) and 5 major hurricanes (220% of normal) were recorded. 1996 continued the active period, with a total of 13 named storms, 9 hurricanes and 6 major hurricanes. 1997 was an anomalous year, when only 7 named storms, 3 hurricanes and 1 major hurricane occurred. From 1998 until 2004, an average of 14 named storms, 8 hurricanes and 4 major hurricanes occurred.
2005 was a record-setting year in many areas. 2005 broke all occurrence records, when a total of 26 named storms (270% of normal), 14 hurricanes (240% of normal) and 7 major hurricanes (305% of normal) plagued the Atlantic. Many other records were broken by the 2005 Atlantic Hurricane Season, including the earliest Category 4 hurricane (Hurricane Dennis, July, 150 mph sustained winds), the strongest hurricane before August (Hurricane Emily, July, 155 mph sustained winds), the most
Category 5 hurricanes (3 – Hurricane Katrina, Hurricane Rita, Hurricane Wilma), and the lowest central pressure ever observed in an Atlantic hurricanes (Hurricane Wilma, 882 mb). The most notable record that was broken this year was the total insured damages done by this year’s hurricane season, which is currently estimated at $41 billion.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
Hurricane reporting and forecasting has improved immensely over the last 150 years. The introduction of sophisticated satellites orbiting the earth, a network of buoys places throughout the ocean basins, and better radar coverage have all added in improved tropical system detection and forecasting. Below is a timeline with notable events that affected hurricane reporting and forecasting.
1975: Saffir-Simpson
Hurricane Scale, 1 st
GOES satellite
1953: Female names given to tropical storms and hurricanes
1968: GOES program developed, birth of the
National Hurricane Center 1988: WSR-88D
(Doppler Radar) developed
2000
1800 1850 1900 1950
1970: National
Data Buoy
Program started
1819: Hurricane described as a “giant moving vortex”
1873: First hurricane warning issued
1943: First plane flight into the eye of a hurricane
1960: 1 st
weather satellite (TIROS program)
1994 & 1998:
Improved NOAA weather satellites launched
Historical hurricane data for the Atlantic Ocean dates back into the 1850s, when the only means of reporting a hurricane in the middle of the ocean consisted of ship reports and land-based observations. Since a global view of the earth was not possible through the 1950s, the accuracy of the total number of tropical systems that actually occurred is low, especially for tropical systems that never made landfall or were on the weak side. In the 1950s and early 1960s, a program headed by a new division called the National Aeronautics and Space Administration (NASA) was developed to place satellites in orbit around the earth. The TIROS Program (Television Infrared Observation Satellite) was NASA's first experimental step to determine if satellites could be useful in the study of the Earth. The TIROS Program's first priority was the development of a meteorological satellite information system. Weather forecasting was deemed the most promising application of space-based observations. TIROS proved extremely successful, providing the first accurate weather forecasts based on data gathered from space. TIROS began continuous coverage of the Earth's weather in 1962 and was used by meteorologists worldwide. It was then that accurate records of all tropical systems – including non-landfalling storms – had started. Another satellite line – the
GOES program (Geostationary Operational Environmental Satellite) – was developed in the late 1960s and launched in the mid-1970s in response to successful testing and deployment of the SMS (Synchronous Meteorological Satellite) modules in the early 1970s. The GOES satellites were developed to take photos of a fixed location (they would move at the same speed as the earth’s rotation). Several GOES satellite modules have been launched since the mid-1970s, with several GOES satellites monitoring the earth to this day.
The late 1960s also brought a need for better sea surface condition monitoring for shipping and meteorological interests. In response to this interest, the National Data Buoy Center was established and started deploying monitoring buoys throughout the Gulf of Mexico and tropical portions of the Atlantic Ocean. These buoys monitor air and seawater temperatures, wave heights, humidity levels, barometric pressure, and wind observations.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift Reinsurance Services
With the introduction of all the afore-mentioned tools, hurricane reporting became more reliable, especially for weaker hurricanes and tropical storms. Due to the development of these tools, it can be assumed that the data before these devices were developed could be missing several tropical storms and hurricanes. Major hurricanes, whose effects would be noticed far from the center of circulation, would have decent data resolution back through the 1920s, and landfalling major hurricane data resolution would be fairly accurate due to population density and telegraph networks back to 1900. Data before 1900 would likely only detail the largest storms that made landfall or if a ship crossed a hurricane or tropical storm’s path. It is with this reasoning that data before 1900 must be carefully considered, as the dataset is likely incomplete. The following graphics show that the data resolution of hurricanes drops off when going back into history but at different levels for all hurricanes, all landfalling hurricanes, major (Category 3 or above) hurricanes and landfalling major hurricanes.
1953: Female names given to tropical storms and hurricanes
1975: Saffir-Simpson
Hurricane Scale, 1 st
GOES satellite
1968: GOES program developed, birth of the
National Hurricane Center
1988: WSR-88D
(Doppler Radar) developed
1800 1850
1819: Hurricane described as a “giant moving vortex”
1873: First hurricane warning issued
Very few to no storms missing
A few storms possibly missing
Several storms likely missing
2000
1900 1950
1943: First plane flight into the eye of a hurricane
1960: 1 st weather satellite (TIROS program)
1970: National
Data Buoy
Program started
1994 & 1998:
Improved NOAA weather satellites launched
1800 1850
1819: Hurricane described as a “giant moving vortex”
1873: First hurricane warning issued
Very few to no storms missing
A few storms possibly missing
Several storms likely missing
1953: Female names given to tropical storms and hurricanes
1975: Saffir-Simpson
Hurricane Scale, 1 st
GOES satellite
1968: GOES program developed, birth of the
National Hurricane Center
1988: WSR-88D
(Doppler Radar) developed
2000
1900 1950
1943: First plane flight into the eye of a hurricane
1960: 1 st
weather satellite (TIROS program)
1970: National
Data Buoy
Program started
1994 & 1998:
Improved NOAA weather satellites launched
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation

Recent Atlantic Basin
Hurricane Frequency Shift
Reinsurance Services
1953: Female names given to tropical storms and hurricanes
1975: Saffir-Simpson
Hurricane Scale, 1 st
GOES satellite
1968: GOES program developed, birth of the
National Hurricane Center
1988: WSR-88D
(Doppler Radar) developed
1800 1850
1819: Hurricane described as a “giant moving vortex”
1873: First hurricane warning issued
Very few to no storms missing
A few storms possibly missing
Several storms likely missing
2000
1900 1950
1943: First plane flight into the eye of a hurricane
1960: 1 st
weather satellite (TIROS program)
1970: National
Data Buoy
Program started
1994 & 1998:
Improved NOAA weather satellites launched
1800 1850
1819: Hurricane described as a “giant moving vortex”
1873: First hurricane warning issued
Very few to no storms missing
A few storms possibly missing
Several storms likely missing
1953: Female names given to tropical storms and hurricanes
1975: Saffir-Simpson
Hurricane Scale, 1 st
GOES satellite
1968: GOES program developed, birth of the
National Hurricane Center
1988: WSR-88D
(Doppler Radar) developed
2000
1900 1950
1943: First plane flight into the eye of a hurricane
1960: 1 st
weather satellite (TIROS program)
1970: National
Data Buoy
Program started
1994 & 1998:
Improved NOAA weather satellites launched
If additional information or assistance is requested, please contact Impact Forecasting by phone at (312) 381-5919, by email at ifsupport@aon.com
, or by the worldwide web at www.impactforecasting.com
.
Copyright © by Impact Forecasting
®
L.L.C
. No claim to original government works. The text and graphics of this publication are provided for informational purposes only. While Impact Forecasting
®
has tried to provide accurate and timely information, inadvertent technical inaccuracies and typographical errors may exist, and Impact Forecasting
®
does not warrant that the information is accurate, complete or current. The data presented at this site is intended to convey only general information on current natural perils and must not be used to make life-or-death decisions or decisions relating to the protection of property, as the data may not be accurate. Please listen to official information sources for current storm information. This data has no official status and should not be used for emergency response decision-making under any circumstances.
Impact Forecasting
®
is a wholly owned subsidiary of Aon Corporation