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A Pacific hurricane is a mature
tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...
that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regions: the eastern (North America to 140°W), central (140°W to 180°), and western (180° to 100°E), while the southern Pacific is divided into 2 sections, the Australian region (90E to 160°E) and the southern Pacific basin between 160°E and 120°W. Identical phenomena in the western north Pacific are called
typhoon A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting fo ...
s. This separation between the two basins has a practical convenience, however, as tropical cyclones rarely form in the central north Pacific due to high
vertical wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...
, and few cross the dateline.


List of seasons


1950s


1960s


1970s


1980s


1990s


2000s


2010s


2020s


History

Documentation of Pacific hurricanes dates to the Spanish colonization of Mexico, when the military and missions wrote about "tempestades". In 1730, such accounts indicated an understanding of the storms. After observing the rotating nature of tropical cyclones, meteorologist
William Charles Redfield William C. Redfield (March 26, 1789 – February 12, 1857) was an American meteorologist. He was the first president of the American Association for the Advancement of Science (1848). Redfield is known in meteorology for his observation of the di ...
expanded his study to include storms in the eastern North Pacific Ocean in the middle of the 19th century. Between June and October 1850, Redfield observed five tropical cyclones along "the southwestern coast of North America", along with one in each of the three subsequent years. In 1895,
Cleveland Abbe Cleveland Abbe (December 3, 1838 – October 28, 1916) was an American meteorologist and advocate of time zones. While director of the Cincinnati Observatory in Cincinnati, Ohio, he developed a system of telegraphic weather reports, daily we ...
reported the presence of many storms between 5° to 15°– N in the eastern Pacific, although many such storms dissipated before affecting the Mexican coast. Two years later, the German Hydrography Office ''Deutsche Seewarte'' documented 45 storms from 1832 to 1892 off the west coast of Mexico. Despite the documentation of storms in the region, the official position of the
United States Weather Bureau The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
denied the existence of such storms. In 1910, the agency reported on global tropical cyclones, noting that "the occurrence of tropical storms is confined to the summer and autumn months of the respective hemispheres and to the western parts of the several oceans." In 1913, the Weather Bureau reinforced their position by excluding Pacific storms among five
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 Ind ...
; however, the agency acknowledged the existence of "certain cyclones that have been traced for a relatively short distance along a northwest course... west of Central America." After
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the mo ...
became a state and the discovery of gold there in 1848, shipping traffic began increasing steadily in the eastern Pacific. Such activity increased further after the
Panama Canal The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a condu ...
opened in 1914, and the shipping lanes moved closer to the coast. By around 1920, Pacific hurricanes were officially recognized due to widespread ship observations, radio service, and a newly created weather network in western Mexico. Within 60 years, further studies of the region's tropical activity indicated that the eastern Pacific is in fact the second most active basin in the world. During the 1920s, a few documents in the
Monthly Weather Review The ''Monthly Weather Review'' is a peer-reviewed scientific journal published by the American Meteorological Society. It covers research related to analysis and prediction of observed and modeled circulations of the atmosphere, including technique ...
reported additional storms within off the Mexican coastline.


The Eastern and Central Pacific hurricane database

The Eastern Pacific hurricane best track database was initially compiled on
magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnet ...
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. 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. 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. 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. Between 1976–1987, the NHC archived best track data from the
Eastern Pacific Hurricane Center The Eastern Pacific Hurricane Center was formerly the center responsible for forecasting Pacific hurricanes in the eastern north Pacific east of 140°W. It was part of the Weather Bureau Forecast Office San Francisco and was based in Redwood Ci ...
(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 The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...
and research done by Samuel Shaw of the
Central Pacific Hurricane Center The Central Pacific Hurricane Center (CPHC) of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central Pacifi ...
(CPHC) in 1981. 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. 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. The archives format was significantly changed during 2013 to include non-synoptic best track times, non-developing tropical depressions and wind radii. During February 2016, the NHC released the 1959 Mexico hurricane's reanalysis, which was the first system to be reassessed, using methods developed for the Atlantic reanalysis process.


Climatology

The presence of a semi-permanent
high-pressure area A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interpl ...
known as the
North Pacific High The North Pacific High is a semi-permanent, subtropical anticyclone located in the northeastern portion of the Pacific Ocean, located northeast of Hawaii and west of California. It is strongest during the northern hemisphere summer and shifts t ...
in the eastern Pacific is a dominant factor against the formation of tropical cyclones in the winter, as the Pacific High results in
wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizon ...
that causes unfavorable, environmental conditions for tropical cyclone formation. Its effects in the central Pacific basin are usually related to keeping cyclones away from the Hawaiian Islands. Due to westward
trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisp ...
s, hurricanes in the Pacific rarely head eastward, unless recurved by a trough. A second factor preventing tropical cyclones from forming during the winter is the occupation of a semi-permanent
low-pressure area In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...
designated the
Aleutian Low The Aleutian Low is a semi-permanent low-pressure system located near the Aleutian Islands in the Bering Sea during the Northern Hemisphere winter. It is a climatic feature centered near the Aleutian Islands measured based on mean sea-level press ...
between January and April. Its presence over western Canada and the northwestern United States contributes to the area's occurrences of precipitation in that duration. In addition, its effects in the central Pacific near 160° W causes tropical waves that form in the area to drift northward into the
Gulf of Alaska The Gulf of Alaska (Tlingit: ''Yéil T'ooch’'') is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the eas ...
and dissipate. The retreat of this low allows the Pacific High to also retreat into the central Pacific, leaving a warm and moist environment in its wake. The
Intertropical Convergence Zone The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal ...
comes northward into the East Pacific in mid-May permitting the formation of the earliest
tropical wave A tropical wave (also called easterly wave, tropical easterly wave, and African easterly wave), in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, whic ...
s, coinciding with the start of the eastern Pacific hurricane season on May 15. The
El Niño-Southern Oscillation EL, El or el may refer to: Religion * El (deity), a Semitic word for "God" People * EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer * El DeBarge, music artist * El Franco Lee (1949–2016), American p ...
also influences the frequency and intensity of hurricanes in the Northeast Pacific basin. During
El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...
events, sea surface temperatures increase in the Northeast Pacific and vertical wind shear decreases. Because of this, an increase in tropical cyclone activity occurs; the opposite happens in the Atlantic basin during El Niño, where increased wind shear creates an unfavorable environment for tropical cyclone formation. Contrary to El Niño,
La Niña La Niña (; ) is an oceanic and atmospheric phenomenon that is the colder counterpart of as part of the broader El Niño–Southern Oscillation (ENSO) climate pattern. The name ''La Niña'' originates from Spanish for "the girl", by an ...
events increase wind shear and decreases sea surface temperatures over the eastern Pacific, while reducing wind shear and increasing sea surface temperatures over the Atlantic.


Eastern North Pacific

Hurricane season runs between May 15 and November 30 each year. These dates encompass the vast majority of tropical cyclone activity in this region. The Regional Specialized Meteorological Center for this basin is the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
'
National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 30 ...
. Previous forecasters are the
Eastern Pacific Hurricane Center The Eastern Pacific Hurricane Center was formerly the center responsible for forecasting Pacific hurricanes in the eastern north Pacific east of 140°W. It was part of the Weather Bureau Forecast Office San Francisco and was based in Redwood Ci ...
and the Joint Hurricane Warning Center. The RSMC monitors the eastern Pacific and issues reports, watches and warnings about tropical weather systems and cyclones as defined by the
World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Intern ...
. This area is, on average, the second-most active basin in the world. There are an average of 16 tropical storms annually, with 9 becoming hurricanes, and 4 becoming major hurricanes. Tropical cyclones in this region frequently affect mainland
Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Gua ...
and the
Revillagigedo Islands The Revillagigedo Islands ( es, Islas Revillagigedo, ) or Revillagigedo Archipelago are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem. They lie approximately from Socorro Island south and southwest of C ...
. Less often, a system will affect the
Continental United States The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...
or
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
. Northbound hurricanes typically reduce to tropical storms or dissipate before reaching the United States: there is only one recorded case of a Pacific system reaching
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the mo ...
as a hurricane in almost 200 years of observations—the 1858 San Diego Hurricane.Michael Chenoweth and
Chris Landsea Christopher William "Chris" Landsea is an American meteorologist, formerly a research meteorologist with the Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory at NOAA, and now the Science and Operations Offic ...

The San Diego Hurricane of 2 October 1858.
Retrieved on 2008-04-19.
Most east Pacific hurricanes originate from a tropical wave that drifts westward across the intertropical convergence zone, and across northern parts of South America. Once it reaches the Pacific, a surface low begins to develop, however, with only little or no convection. After reaching the Pacific, it starts to move north-westward and eventually west. By that time, it develops convection and thunderstorm activity from the warm ocean temperatures but remains disorganized. Once the tropical wave becomes organized, it becomes a tropical depression. Formation usually occurs from south of the Gulf of Tehuantepec to south of Baja California with a more westerly location earlier in the season. In the eastern Pacific, development is more centered than anywhere else. If wind shear is low, a tropical cyclone can undergo
rapid intensification In meteorology, rapid intensification is a situation where a tropical cyclone intensifies dramatically in a short period of time. The United States National Hurricane Center defines rapid intensification as an increase in the maximum sustained w ...
as a result of very warm oceans, becoming a major hurricane. Tropical cyclones weaken once they reach unfavorable areas for a tropical cyclone formation. Their remnants sometimes reach Hawaii and cause showers there. There are a few types of Pacific hurricane tracks: one is a westerly track, another moves north-westward along Baja California and another moves north. Sometimes storms can move north-east either across Central America or mainland Mexico and possibly enter the Caribbean Sea becoming a North Atlantic basin tropical cyclone, but these are rare.


Central Pacific

Hurricane season runs from June 1 to November 30, with a strong peak in August and September. However, tropical cyclones have formed outside those dates. Should a tropical cyclone enter the central north Pacific from the western north Pacific, where they occur year-round, or from the eastern north Pacific, where the season starts in May, it is not known if such a system will be considered out of season or not. The
Central Pacific Hurricane Center The Central Pacific Hurricane Center (CPHC) of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central Pacifi ...
is the RSMC for this basin and monitors the storms that develop or move into the defined area of responsibility. A previous forecaster was the Joint Hurricane Warning Center. Central Pacific hurricanes are rare and on average 3 or 4 storms form or move in this area per year. Most often, storms that occur in the area are weak and often decline in strength upon entry. The only land masses impacted by tropical cyclones in this region are
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...
and
Johnston Atoll Johnston Atoll is an unincorporated territory of the United States, currently administered by the United States Fish and Wildlife Service (USFWS). Johnston Atoll is a National Wildlife Refuge and part of the Pacific Remote Islands Marine Nation ...
. Due to the small size of the islands in relation to the Pacific Ocean, direct hits and landfalls are rare.


Steering factors

Hurricanes in the Eastern Pacific tend to move westward out to sea, harming no land—unless they cross into the Central Pacific or Western Pacific basins, in which case they might harm land such as Hawaii or Japan. However, hurricanes can recurve to the north or northeast, hitting Central America or Mexico early and late in the hurricane season.


Extremes

*The strongest recorded Pacific hurricane was Hurricane Patricia (2015), with 1-minute maximum sustained winds of 215 mph (345 km/h) and a minimum
barometric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...
of 872 mbar (hPa; 25.75 inHg). This ranks Patricia as the strongest tropical cyclone globally in terms of 1-minute sustained winds and the second strongest globally in terms of barometric pressure. *
Hurricane John (1994) Hurricane John, also known as Typhoon John, was both the longest-lasting and the farthest-traveling tropical cyclone ever observed. John formed during the 1994 Pacific hurricane season, which had above-average activity due to the El Niño of 1994 ...
was the longest-lived and farthest-travelling tropical cyclone worldwide, traversing 7,165 mi (13,280 km) in 30 days and 18 hours. *The 1959 Mexico hurricane was the deadliest Pacific hurricane, causing 1,800 fatalities mostly in
Colima Colima (), officially the Free and Sovereign State of Colima ( es, Estado Libre y Soberano de Colima), is one of the 31 states that make up the 32 Federal Entities of Mexico. It shares its name with its capital and main city, Colima. Colima i ...
and
Jalisco Jalisco (, , ; Nahuatl: Xalixco), officially the Free and Sovereign State of Jalisco ( es, Estado Libre y Soberano de Jalisco ; Nahuatl: Tlahtohcayotl Xalixco), is one of the 31 states which, along with Mexico City, comprise the 32 Federal ...
.


See also

*
Atlantic hurricane An Atlantic hurricane, also known as tropical storm or simply hurricane, is a tropical cyclone that forms in the Atlantic Ocean, primarily between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis ...
* Cordonazo wind *
Tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...
*
Typhoon A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting fo ...
*
Atlantic hurricane season The Atlantic hurricane season is the period in a year from June through November when tropical cyclones form in the Atlantic Ocean, referred to in North American countries as hurricanes, tropical storms, or tropical depressions. In addition ...
* Pacific typhoon climatology * Pacific typhoon season * North Indian Ocean tropical cyclone season * South-West Indian Ocean tropical cyclone season * Australian region tropical cyclone season * South Pacific tropical cyclone season *
South Atlantic tropical cyclone South Atlantic tropical cyclones are unusual weather events that occur in the Southern Hemisphere. Strong wind shear, which disrupts the formation of cyclones, as well as a lack of weather disturbances favorable for development in the South Atl ...
* Mediterranean tropical-like cyclone *
List of tropical cyclone records This is a condensed list of worldwide tropical cyclone records set by different storms and seasons. Major records See also * List of weather records ** Tornado records * List of the most intense tropical cyclones * List of wettest trop ...


References

{{DEFAULTSORT:Pacific Hurricane Pacific *