Hurricane John (1994)

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Hurricane John
Typhoon John
Category 5 major hurricane (SSHWS/NWS)
Hurricane John 24 aug 1994 0255Z.jpg
Hurricane John near peak intensity to the south of Hawaii on August 24
FormedAugust 11, 1994
DissipatedSeptember 10, 1994
Duration4 weeks and 2 days
Highest winds 1-minute sustained:175 mph (280 km/h)
Lowest pressure≤ 929 mbar (hPa); 27.43 inHg
FatalitiesNone
Damage$15 million (1994 USD)
Areas affected Hawaii, Johnston Atoll, Alaska
Part of the 1994 Pacific hurricane season and the 1994 Pacific typhoon season

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 1994–95, [1] and peaked as a Category 5 hurricane on the Saffir–Simpson hurricane wind scale, the highest categorization for hurricanes.

Tropical cyclone Is a rotating storm system

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. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, and a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or Indian Ocean, comparable storms are referred to simply as "tropical cyclones" or "severe cyclonic storms".

1994 Pacific hurricane season hurricane season in the Pacific Ocean

The 1994 Pacific hurricane season was the final season of the eastern north Pacific's consecutive active hurricane seasons that unofficially started in 1982. The season officially started on May 15, 1994, in the eastern Pacific, and on June 1, 1994, in the central Pacific, and lasted until November 30, 1994. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. The first tropical cyclone formed on June 18, while the last system dissipated on October 26. This season, twenty-two tropical cyclones formed in the north Pacific Ocean east of the dateline, with all but two becoming tropical storms or hurricanes. A total of 10 hurricanes occurred, including five major hurricanes.

El Niño Warm phase of a cyclic climatic phenomenon in the Pacific Ocean

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, including the area off the Pacific coast of South America. The ENSO is the cycle of warm and cold sea surface temperature (SST) of the tropical central and eastern Pacific Ocean. El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. El Niño phases are known to occur close to four years, however, records demonstrate that the cycles have lasted between two and seven years. During the development of El Niño, rainfall develops between September–November. The cool phase of ENSO is La Niña, with SSTs in the eastern Pacific below average, and air pressure high in the eastern Pacific and low in the western Pacific. The ENSO cycle, including both El Niño and La Niña, causes global changes in temperature and rainfall.

Contents

Over the course of its existence, John followed a 7,165-mile (13,280-km) path from the eastern Pacific to the western Pacific and back to the central Pacific, lasting 31 days in total. [2] Because it existed in both the eastern and western Pacific, John was one of a small number of tropical cyclones to be designated as both a hurricane and a typhoon. Despite lasting for a full month, John barely affected land at all, bringing only minimal effects to the Hawaiian Islands and the United States military base on Johnston Atoll. Its remnants later affected Alaska.

Hawaiian Islands An archipelago in the North Pacific Ocean, currently administered by the US state of Hawaii

The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaiʻi in the south to northernmost Kure Atoll. Formerly the group was known to Europeans and Americans as the Sandwich Islands, a name chosen by James Cook in honor of the then First Lord of the Admiralty John Montagu, 4th Earl of Sandwich. The contemporary name is derived from the name of the largest island, Hawaii Island.

Military base facility directly owned and operated by or for the military

A military base is a facility directly owned and operated by or for the military or one of its branches that shelters military equipment and personnel, and facilitates training and operations. A military base provides accommodations for one or more units, but it may also be used as a command center, training ground or proving ground. In most cases, military bases rely on outside help to operate. However, certain complex bases are able to endure on their own for long periods because they are able to provide food, water and other life support necessities for their inhabitants while under siege. Military bases for military aviation are called military air bases. Military bases for military ships are called naval bases.

Johnston Atoll United States Minor Outlying Islands

Johnston Atoll, also known as Kalama Atoll to Native Hawaiians, is an unincorporated territory of the United States currently administered by the United States Fish and Wildlife Service. Johnston Atoll is a National Wildlife Refuge and is closed to public entry. Limited access for management needs is only by Letter of Authorization from the U.S. Air Force and Special Use Permit from the U.S. Fish and Wildlife Service.

Meteorological history

Map plotting the track and the intensity of the storm, according to the Saffir-Simpson scale John 1994 track.png
Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

The origins of Hurricane John were thought by the United States National Hurricane Center (NHC) to be from a tropical wave that moved off the coast of Africa on July 25, 1994. [3] [4] The wave subsequently moved across the Atlantic Ocean and Caribbean without distinction, before it crossed Central America and moved into the Eastern Pacific Ocean on or around August 8. [3] [4] Upon entering the Eastern Pacific the wave gradually developed, before the NHC initiated advisories on the system and designated it as Tropical Depression Ten-E during August 11. [5] The system was at this time moving westwards and located around 345 miles (555 km) to the south-southeast of Acapulco, Mexico. [3] [4] Quickly developing banding features and well-defined outflow, it was upgraded to a tropical storm and named John later that day. [2]

National Hurricane Center Division of the United States National Weather Service

The National Hurricane Center (NHC) is the division of the United States' National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean. The agency, which is co-located with the Miami branch of the National Weather Service, is situated on the campus of Florida International University in University Park, Florida.

Tropical wave type of atmospheric trough

Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which moves from east to west across the tropics, causing areas of cloudiness and thunderstorms. West-moving waves can also form from the tail end of frontal zones in the subtropics and tropics, and may be referred to as easterly waves, but these waves are not properly called tropical waves; they are a form of inverted trough sharing many characteristics with fully tropical waves. All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeastern Pacific basins. A tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data.

Acapulco City and municipality in Guerrero, Mexico

Acapulco de Juárez, commonly called Acapulco, is a city, municipality and major seaport in the state of Guerrero on the Pacific coast of Mexico, 380 kilometres (240 mi) south of Mexico City. Acapulco is located on a deep, semicircular bay and has been a port since the early colonial period of Mexico's history. It is a port of call for shipping and cruise lines running between Panama and San Francisco, California, United States. The city of Acapulco is the largest in the state, far larger than the state capital Chilpancingo. Acapulco is also Mexico's largest beach and balneario resort city.

A strong ridge of high pressure over the northeastern Pacific Ocean forced John westward, where upper level wind shear kept John a tropical storm. Intensity fluctuated considerably, however, as shear levels varied. More than once, shear cleared away most of the clouds above John and nearly caused it to weaken to a tropical depression. [2] However, after eight days of slow westward movement across the Pacific Ocean, shear lessened greatly on August 19, and John intensified significantly and was designated as a hurricane at 17:00 PDT. During an eighteen-hour period between August 19 and August 20, John further strengthened from a weak Category 1 hurricane to a Category 3 major hurricane. Around 1100 PDT on August 20, John crossed into the central Pacific, the first of three basin crosses John would make. [2]

Wind shear

Wind shear, sometimes referred to as wind gradient, is a difference in wind speed or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with change in altitude. Horizontal wind shear is a change in wind speed with change in lateral position for a given altitude.

After entering the central Pacific, John left the area monitored by the NHC and was instead monitored by the Central Pacific Hurricane Center (CPHC). As the storm moved slowly westward, Hurricane John continued to strengthen considerably in an increasingly favorable environment well south of the Hawaiian Islands; on August 22, John was designated a Category 5 hurricane on the Saffir–Simpson hurricane scale (the highest classification for hurricanes) and later that day (by Hawaii Standard Time) reached its peak intensity, with 1-minute sustained winds of 175 miles per hour (280 km/h) and a minimum central pressure of 929 millibars (27.4 inHg). [6] Also, on August 22 (by Hawaii Standard Time), John made its closest approach to the Hawaiian Islands, 345 miles (500 km) to the south. John had threatened to turn north and affect the islands days before, but the ridge of high pressure that typically shields the islands from hurricanes kept John on its southerly path. Nonetheless, heavy rains and wind from the outer bands of John affected the islands. [6]

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 Pacific region: from the equator northward, 140°W–180°W, most significantly for Hawai‘i. It is the Regional Specialized Meteorological Center (RSMC) for tropical cyclones in this region, and in this capacity is known as RSMC Honolulu.

Hawaii–Aleutian Time Zone UTC−10:00 during standard time; UTC−09:00 during daylight saving

The Hawaii–Aleutian Time Zone observes Hawaii–Aleutian Standard Time (HST), by subtracting ten hours from Coordinated Universal Time (UTC−10:00). The clock time in this zone is based on the mean solar time of the 150th meridian west of the Greenwich Observatory.

With the Hawaiian Islands behind it, John began a slow turn to the north, taking near-direct aim at Johnston Atoll, a small group of islands populated only by a United States military base. The storm slowly weakened from its peak as a Category 5 hurricane in the face of increasing shear, dropping down to a Category 1 hurricane with 90 miles per hour (145 km/h) maximum winds. On August 25 local time, John made its closest approach to the Johnston Atoll only 15 miles (24 km) to the north. On Johnston Atoll, sustained winds were reported up to 60 miles per hour (95 km/h), the equivalent of a strong tropical storm, and gusts up to 75 miles per hour (120 km/h) were recorded. [7]

Hurricane John at its tertiary peak strength in the far north-central Pacific Ocean. There is also an extratropical cyclone north of John. Hurricane John Tertiary Peak.jpg
Hurricane John at its tertiary peak strength in the far north-central Pacific Ocean. There is also an extratropical cyclone north of John.

Clearing Johnston Atoll, John turned to the northwest and began strengthening again as shear decreased. On August 27 local time, John reached a secondary peak strength of 135 miles per hour (210 km/h), and shortly thereafter it crossed the International Date Line at approximately 22° N and came under the surveillance of the Guam branch of the Joint Typhoon Warning Center (JTWC). By crossing into the western Pacific, John also became a typhoon and was referred to as Typhoon John during its time in the western Pacific. [7] Immediately after crossing the Date Line, John again weakened and its forward motion stalled. By September 1, John had weakened to a tropical storm and was nearly motionless just west of the Date Line. There, John lingered for six days while performing a multi-day counterclockwise loop. On September 7, a trough moved into the area and quickly moved John to the northeast. John crossed the Date Line again on September 8 and reentered the central Pacific. [7]

After reentering the central Pacific, John briefly reached a tertiary peak strength of 90 miles per hour (145 km/h), a strong Category 1 hurricane, well to the north of Midway Island. However, the trough was rapidly pulling apart John's structure, and the cold waters of the northern central Pacific were not conducive to a tropical cyclone. On September 10, the 120th advisory was released on the system, finally declaring John to have become extratropical approximately 1,000 miles (1600 km) south of Unalaska Island. [7]

Forecasting difficulties

During John's time in the Western North Pacific, the Joint Typhoon Warning Center (JTWC) had particular difficulty in forecasting and even estimating the strength of John. John weakened considerably after entering the Western North Pacific, and, before estimates were later revised, four consecutive advisories were issued that declared John a tropical depression. Each of these advisories called for imminent dissipation. As John persisted and did not dissipate as the JTWC had predicted, it was upgraded to a minimal tropical storm in the next advisory.

At the same time, however, two separate ship reports indicated that John had sustained winds of at least 55  knots (100 km/h, 65 mph), far stronger than the advisory strength of 35 knots (65 km/h, 40 mph). John would go on to restrengthen into a strong Category 1 hurricane after reentering the Central North Pacific, defying all JTWC predictions. After later reanalysis, the JTWC raised the estimated wind speeds of John for every advisory from 1200 UTC September 1 to its final advisory exactly a week later by at least 5 knots (9 km/h, 6 mph) and as much as 25 knots (46 km/h, 29 mph). [8]

Records

John's 31-day existence made the hurricane the longest-lasting tropical cyclone recorded in both the Pacific Ocean and worldwide, surpassing both Hurricane Tina's previous record in the Pacific of 24 days in the 1992 season and the 1899 San Ciriaco hurricane's previous world record of 28 days in the 1899 Atlantic season. [9] In addition, despite its slow movement throughout much of its path, John was the farthest-traveling tropical cyclone in both Pacific Ocean and worldwide, with a distance traveled of 7,165 miles (13,280 km), out-distancing previous record holders Hurricane Fico in the Pacific of 4,700 miles (8,700 km) in the 1978 season and Hurricane Faith worldwide of 6,850 miles (12,700 km) in the 1966 Atlantic season. [10]

Pressure readings from John's peak are not consistently available as the CPHC did not monitor pressures at the time, but Air Force Reserve aircraft did measure a surface pressure of 929 mbar (hPa), making John one of the most intense hurricanes recorded in the central Pacific; both hurricanes Emilia and Gilma of 1994, as well as hurricanes Ioke of 2006 and Lane and Walaka of 2018 all recorded lower pressures in the central Pacific. However, all five had lower wind speeds than John. (Intensity is measured by minimum central pressure, which correlates with but is not directly linked to wind speeds). John was also only the fourth Category 5 hurricane recorded in the central Pacific (the first was Hurricane Patsy in 1959, the second was Hurricane Emilia and the third one was Hurricane Gilma, both earlier in 1994). John also possessed the highest recorded wind speed in a central Pacific hurricane, 175 mph (280 km/h), a record shared with the aforementioned Patsy of 1959. [6] Since 1994, only three Category 5 hurricanes, Ioke in 2006, and hurricanes Lane and Walaka in 2018 have formed in or entered into the Central Pacific. Despite this however, John's pressure record is incomplete; the 929 mbar reading was only measured when the winds were 160 mph; there is no pressure reading when it had winds of 175 mph, so it could have been stronger than Emilia, Gilma, Ioke, Lane, or Walaka. [11] In addition, John was the first tropical cyclone to form in the east Pacific, east of 140°W, and also exist as a typhoon once it crossed 180°W; a feat only matched by Hurricane Genevieve in 2014. [12]

Additionally, counting only storms recognized by all north Pacific official Regional Specialized Meteorological Centers, John was only the fourth of seven tropical cyclones to exist in all three tropical cyclone basins in the Pacific Ocean. [13] [11] [14] [15] Also, John was the fifth of seven tropical cyclones to enter the central Pacific from the western Pacific. [7] [13] [14] [15] Finally, John was one of only five tropical cyclones to cross the Date Line twice. [13] [16]

Impact

Satellite image of Hurricane John as a Category 5 storm with winds of 165 mph (270 km/h) Hurricane John 23 aug 1994 1739Z.jpg
Satellite image of Hurricane John as a Category 5 storm with winds of 165 mph (270 km/h)

John affected both the Hawaiian Islands and Johnston Atoll, but only lightly. While John passed over 345 miles (550 km) to the south of Hawaiʻi, the islands did experience strengthened trade winds and rough surf along the southeast- and south-facing shores, and, while moving westward, on west-facing shores as well. [7] The waves, ranging from 6 to 10 ft (1.8 to 3.0 m) in height, flooded beach parks in Kailua-Kona. [17] Additionally, heavy rains on the Big Island of Hawaiʻi caused minor, localized flooding and some short-term road closures. No deaths, injuries or significant damages were reported in Hawaiʻi. [7]

Although John passed within 25 km (16 mi) of Johnston Atoll, it had weakened greatly to a Category 1 system by closest approach. [7] Prior to the storm's arrival, waves between 20 and 30 ft (6.1 and 9.1 m) were reported on the island. [18] Additionally, in the Northern Hemisphere, the strongest winds and heaviest rain lie to the north of a tropical cyclone, so the atoll, which lay to the south of the storm's path, was spared the brunt of the storm. Nonetheless, the 1,100-man personnel for the United States military base on Johnston Atoll had been evacuated to Honolulu as a precaution while John approached. Damage to structures was considerable, but the size of the island and relative functionality of the base led to low damage; monetary losses were estimated at close to $15 million (1994 US$). [7]

The remnants of John moved through the Aleutian Islands, producing a wind gust of 46 mph (74 km/h) in Unalaska. The storm brought a plume of warm air, and two stations recorded a high temperature of 66 °F (19 °C). [19]

See also

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References

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