Hurricane Neki
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Hurricane Neki was the final
tropical cyclone A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its locat ...
of the
2009 Pacific hurricane season The 2009 Pacific hurricane season was the most active Pacific hurricane season since 1997 Pacific hurricane season, 1997. The season officially started on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific; they both ended on ...
. It developed on October 18 as an unusually large disturbance from a
trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...
south of
Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...
. Moving northwestward, it organized only slowly at first due to its large size. After reaching hurricane status on October 21, Neki intensified at a much faster rate and peaked with winds of 125 mph (205 km/h). It later turned to the north and north-northeast and weakened due to hostile conditions. While passing through the
Papahānaumokuākea Marine National Monument The Papahānaumokuākea Marine National Monument (PMNM) (roughly ) is a World Heritage Site, World Heritage listed National monument (United States), U.S. national monument encompassing of ocean waters, including ten islands and atolls of th ...
, Neki was downgraded to a tropical storm after the center became exposed from the deepest convection. It caused little impact in the island chain. After stalling and executing a small loop, Neki resumed its northward track and dissipated on October 27.


Meteorological history

The origins of Hurricane Neki were from a surface
trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...
that persisted near the equator in the central Pacific Ocean in the middle of October 2009. A weak tropical disturbance became evident in the trough on October 15, and three days later the system began developing curved bands of convection on its northern and southern periphery. This created an unusually large
gyre In oceanography, a gyre () is any large system of ocean surface currents moving in a circular fashion driven by wind movements. Gyres are caused by the Coriolis effect; planetary vorticity, horizontal friction and vertical friction determine the ...
for the region. Following the formation of a well-defined circulation, it is estimated the system developed into Tropical Depression Three-C late on October 18, about 730 mi (1175 km) south of
Ka Lae Ka Lae (), also known as South Point, is the southernmost point of the Hawaii (island), Big Island of Hawaii and Extreme points of the United States, of the 50 United States. The Ka Lae area is registered as a National Historic Landmark, Natio ...
,
Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...
. Upon developing into a tropical cyclone, the storm was moving west-northwestward, influenced by a
ridge A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
to its north. It was located over an area of warm
sea surface temperature Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
s and moderate
wind shear Wind shear (; also written 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 ...
, which favored gradual intensification. The convection diminished during a diurnal cycle before redeveloping the next day. Maintaining an unusually large size, the depression slowly organized, gradually separating from the trough from which it developed. On October 19, the CPHC upgraded it to Tropical Storm Neki, and shortly thereafter the storm turned toward the northwest. By the next day, the cyclone resembled the structure of a
monsoon depression The monsoon trough is a convergence zone between the wind patterns of the southern and northern hemispheres. It is a portion of the Intertropical Convergence Zone in the Western Pacific,Bin WangThe Asian Monsoon.Retrieved 2008-05-03. and is depi ...
typically found in the western Pacific Ocean. However, the structure began to more resemble a tropical cyclone after the outermost convection diminished and the thunderstorms around the center increased. Following the development of a banding-eye feature, Neki intensified into a hurricane early on October 21 about 625 mi (1010 km) southwest of
Honolulu, Hawaii Honolulu ( ; ) is the List of capitals in the United States, capital and most populous city of the U.S. state of Hawaii, located in the Pacific Ocean. It is the county seat of the Consolidated city-county, consolidated City and County of Honol ...
, or about 335 mi (535 km) east-southeast of
Johnston Atoll Johnston Atoll is an Unincorporated territories of the United States, unincorporated territory of the United States, under the jurisdiction of the United States Air Force (USAF). The island is closed to public entry, and limited access for mana ...
. After reaching hurricane status, Neki began rapidly intensifying as it turned northward, due to an approaching upper-level trough to its north. An
anticyclone 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 ...
aloft provided favorable
outflow Outflow may refer to: *Capital outflow, the capital leaving a particular economy *Bipolar outflow, in astronomy, two continuous flows of gas from the poles of a star * Outflow (hydrology), the discharge of a lake or other reservoir system *Outflow ...
, which contributed in the strengthening. Early on October 22, Neki reached its peak winds of 125 mph (205 km/h) about 215 mi (345 km) northeast of Johnston Atoll, based on estimates from satellite imagery using the
Dvorak technique The Dvorak technique (developed between 1969 and 1984 by Vernon Dvorak) is a widely used system to estimate tropical cyclone intensity (which includes tropical depression, tropical storm, and hurricane/typhoon/intense tropical cyclone intensities ...
. Afterward, the trough that influenced the hurricane's track also began restricting westerly outflow and increasing wind shear, which caused a steady weakening trend. It maintained major hurricane status – a Category 3 major hurricane on the Saffir–Simpson Hurricane Scale – for about 24 hours, during which the track turned toward the north-northeast. The weakening and deterioration of the storm's structure became more marked on October 23 after the thunderstorms failed to persist over the center. While approaching the
Papahānaumokuākea Marine National Monument The Papahānaumokuākea Marine National Monument (PMNM) (roughly ) is a World Heritage Site, World Heritage listed National monument (United States), U.S. national monument encompassing of ocean waters, including ten islands and atolls of th ...
, Neki weakened to tropical storm status. Continued wind shear exposed the circulation from the convection, although further weakening was slow to occur. On October 24, Neki made its closest approach to land after passing within 13 mi (21 km) of the uninhabited Necker Island. Its forward motion slowed due to a building ridge to the north, causing the storm to execute a small loop. Despite the shear, Neki was initially able to continue developing thunderstorms, although cooler water temperatures resulted in further weakening. The storm resumed its northward motion after the ridge receded to the east, and on October 26 Neki weakened to a tropical depression once the circulation decoupled from the thunderstorms. Neki dissipated on the next day, as the storm's center became elongated ahead of an approaching
cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface Trough (meteorology), trough of Low-pressure area, low pressure. It often forms behind an extratropica ...
.


Preparations and impact

Although still a minimal tropical storm at the time, the CPHC anticipated Neki to become a hurricane as it tracked northwestward. As such, they issued a
hurricane watch Tropical cyclone warnings and watches are alerts issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local pop ...
for
Johnston Island Johnston Atoll is an unincorporated territory of the United States, under the jurisdiction of the United States Air Force (USAF). The island is closed to public entry, and limited access for management needs is only granted by a letter of autho ...
on the afternoon of October 19. The following day, the hurricane watch was replaced by a tropical storm watch as Neki was no longer forecast to pass close enough to the island to produce hurricane-force winds. Later that day, a hurricane watch was issued for the
Papahānaumokuākea Marine National Monument The Papahānaumokuākea Marine National Monument (PMNM) (roughly ) is a World Heritage Site, World Heritage listed National monument (United States), U.S. national monument encompassing of ocean waters, including ten islands and atolls of th ...
for areas between the
French Frigate Shoals The French Frigate Shoals (Hawaiian language, Hawaiian: Kānemilohai) is the largest atoll in the Northwestern Hawaiian Islands, located about northwest of Honolulu, Hawaii, Honolulu. Its name commemorates France, French explorer Jean-Fran ...
and
Lisianski Island Lisianski Island (Hawaiian language, Hawaiian: ''Papa‘āpoho'') is one of the Northwestern Hawaiian Islands, with a land area of and a maximum elevation of above sea level. It is a low, flat sand and coral island about northwest of Honolulu, ...
. The following morning, a supplementary hurricane warning was issued for the monument for areas between the French Frigate Shoals and
Nihoa Nihoa (; or ), also known as Bird Island or Moku Manu, is the tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands (NWHI). The island is located at the southern end of the NWHI chain, southeast of Necker ...
. Additionally, the tropical storm watch for Johnston Island was discontinued. Early on October 22, the hurricane watch for Lisianski Island to Marco Reef was replaced by a tropical storm watch. Several hours later, the CPHC discontinued this watch. Early on October 23, as Neki weakened to a tropical storm, the hurricane warning for areas between the French Frigate Shoals and Nihoa was replaced by a tropical storm warning. The tropical storm warning remained in effect for more than a day before being canceled during the afternoon of October 24. As the hurricane turned northward and was seen as a threat to the Hawaiian Islands, officials in the Papahanaumokuakea requested that all 17 personnel in the region be evacuated. Several days before the storm passed through the islands, an
AC-130 The Lockheed AC-130 gunship is a heavily armed, long-endurance, attack aircraft, ground-attack variant of the C-130 Hercules transport, fixed-wing aircraft. It carries a wide array of ground-attack weapons that are integrated with sensors, nav ...
aircraft was flown to the area and evacuated the people stationed on Tern Island, while a
National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with Weather forecasting, forecasting weather, monitoring oceanic and atmospheric conditions, Hydrography, charting the seas, ...
vessel evacuated the temporary residents on Laysan Island. Hurricane Neki caused relatively little damage in the Papahanaumokuakea Marine National Monument. All of the structures were undamaged; however, two small natural habitat islands, Round and Disappearing Islands, were affected substantially. The former lost some land area and the latter was completely washed away. The storm damaged coral reefs in the region, which quickly regrew in the subsequent years. Neki did not affect the state of Hawaii, other than producing high clouds across the region.


See also

* List of Category 3 Pacific hurricanes *
Hurricane Walaka Hurricane Walaka was a strong tropical cyclone that brought Wind wave, high surf and a powerful storm surge to the Northwestern Hawaiian Islands. Walaka was the nineteenth named storm, twelfth hurricane, eighth major hurricane, and second Categ ...
- a strong hurricane in 2018 that took a similar path through the northwestern Hawaiian islands


References


External links

{{DEFAULTSORT:Neki Neki Neki Neki 2009 in Hawaii Neki