The National Hurricane Centers HURricane DATabases (HURDAT) are two separate databases that contain details on tropical cyclones, that have occurred within the Atlantic Ocean and Eastern Pacific Ocean since either 1851 or 1949.

The Eastern Pacific database was originally compiled at the NHC during 1976, to help with the initialization with two tropical cyclone forecast models. Initially tracks for the Central Pacific region and tracks for tropical depressions, that did not develop into tropical storms or hurricanes were not included within the database. Over the next few years tracks were archived best track data from the Eastern Pacific Hurricane Center (EPHC) were archived by the NHC on an annual basis. During 1982 the NHC started to include data on Central Pacific tropical storms and hurricanes within the database, before they took over the responsibility for issuing advisories during 1988. The format of the Eastern Pacific database was subsequently significantly changed during 2013 to include non-synoptic best track times and non-developing tropical depressions.

The Atlantic hurricane database[edit]

The initial requirement for computerized tropical cyclone data at the National Hurricane Centre (NHC), came during the mid 1960s after NASA's Apollo space programme requested data on the climatological impact of tropical cyclones on launches of space vehicles at the Kennedy Space Center.^[1] The basic data was taken by John Hope and Charles Neumman from the National Weather Records North Atlantic Tropical Cyclone deck number 988 who updated it to include data from 1886 - 1968 and applied several corrections to the data.^[2]

The original database of six-hourly positions and intensities were put together in the 1960s in support of the Apollo space program to help provide statistical track forecast guidance. In the intervening years, this database – which is now freely and easily accessible on the Internet from the National Hurricane Center's (NHC's) Webpage – has been utilized for a wide variety of uses: climatic change studies, seasonal forecasting, risk assessment for county emergency managers, analysis of potential losses for insurance and business interests, intensity forecasting techniques and verification of official and various model predictions of track and intensity.

HURDAT was not designed with all of these uses in mind when it was first put together and not all of them may be appropriate given its original motivation. HURDAT contains numerous systematic as well as some random errors in the database. Additionally, analysis techniques have changed over the years at NHC as their understanding of tropical cyclones has developed, leading to biases in the historical database. Another difficulty in applying the hurricane database to studies concerned with landfalling events is the lack exact location, time and intensity at hurricane landfall.

In 2013, the archives format was significantly changed to include non-synoptic best track times, non-developing tropical depressions and wind radii.^[3]

The Eastern and Central Pacific hurricane database[edit]

The Eastern Pacific best track database was initially compiled on magnetic tape in 1976 for the seasons between 1949 and 1975, at the NHC to help with the development of two tropical cyclone forecast models, which required tracks of past cyclones as a base for its predictions.^[4][5] The database was based on records held by the United States Navy and were interpolated from 12 hourly intervals to 6 hourly intervals based on a scheme devised by Hiroshi Akima in 1970.^[6][7] Initially tracks for the Central Pacific region and tracks for tropical depressions that did not develop into tropical storms or hurricanes were not included within the database.^[7] After the database had been created Arthur Pike of the NHC made some internal adjustments, while in 1980 a review was made by Arnold Court under contract from the United States National Weather Service and resulted in additions and/or modifications to 81 tracks in the database.^[6][8] Between 1976 - 1987, the NHC archived best track data from the Eastern Pacific Hurricane Center (EPHC), and in 1982 started including information on Central Pacific tropical storms and hurricanes started to be included in the database based on data from the Joint Typhoon Warning Center and research done by Samuel Shaw of the Central Pacific Hurricane Center (CPHC) in 1981.^[4][6] The format of the database was completely revised by the NHC during 1984, so that the format could resemble the Atlantic database before they took over the warning responsibility from the EPHC for the Eastern Pacific during 1988.^[6][8][9] During 2008 and 2013 several revisions were made to the database to extend tracks in land, based on reports in the Mariners Weather Log and extrapolation of the tracks since the EPHC stopped issuing advisories on systems before they made landfall.^[10] The archives format was significantly changed during 2013 to include non-synoptic best track times, non-developing tropical depressions and wind radii.^[11]

Reanalysis projects[edit]

During 1959 a technical paper was published by the United States Weather Bureau, which consolidated several sources of records in to a single publication.^[12] These sources included annual summaries that had been published in the Monthly Weather Review at various times since 1922, unpublished materials from the Hurricane forecast offices and other studies on hurricanes and hurricane climatology back to around 1886.^[12] While combining the sources, position errors of over 100 miles (160 km) were found for several hurricanes shown in more than one source.^[12] Therefore, the positions of all of the systems that were considered to have tropical characteristics, were compared with the historical weather maps of the daily synoptic series.^[12] The most reliable positions and intensities were then plotted on a series of annual track charts, before being reviewed by the hurricane forecast centres, Extended Forecast Section and the National Hurricane Research Project.^[12] The most accurate and consistent locations from the reviews were then plotted on the maps and published.^[12]

Both the Atlantic and Eastern Pacific HURDAT Databases are in the process of being re-analysed by the NHC, as they contain several random and systematic errors that have become apparent as analysis techniques have developed over the years.^[13][14] For the Atlantic HURDAT efforts to re-analyse the whole of the period between 1851 to the end of the 20th Century got under way in 2001 when data for the years 1851 to 1856 were added to the database. These additions and changes were based on the groundbreaking work of the late Jose Fernandez-Partagas, who uncovered numerous, previously undocumented, hurricanes from the late 19th and early 20th centuries. The second time the database was updated was August 2002 when Hurricane Andrew was upgraded to a Category 5 hurricane. In addition to these changes additional analyses, digitization and quality control of the data was carried out by researchers at the NOAA Hurricane Research Division. By 2010, re-analysis had been completed as far as the 1930 Atlantic season. Official changes to the Atlantic hurricane database are approved by the National Hurricane Center Best Track Change Committee.

During March 2014 HURDAT was updated with the results of the reanalysis for the seasons between 1946 and 1950, with 9 tropical storms added to the database.^[15][16] Hurricane Camille's reanalysis was expedited and published during April 2014, after the management of the National Hurricane Center realised a need to answer the question: "Which is the strongest hurricane to have struck the United States?"^[17][18] During May 2015, HURDAT was revised with the results of the reanalysis for the seasons between 1951 and 1955, with 12 new tropical storms added to the database.^[15][19]

References[edit]