Cyclone Ivy
Encyclopedia
Severe Tropical Cyclone Ivy (Fiji Meteorological Service
Fiji Meteorological Service
The Fiji Meteorological Service is a Department of the government of Fiji responsible for providing weather forecasts and is based in Nadi. Since 1995, FMS has been responsible for naming and tracking tropical cyclones in the Southwest Pacific region...

 designation: 05F, Joint Typhoon Warning Center
Joint Typhoon Warning Center
The Joint Typhoon Warning Center is a joint United States Navy – United States Air Force task force located at the Naval Maritime Forecast Center in Pearl Harbor, Hawaii...

 designation: 13P) was a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...

 that affected about 25% of the population of Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...

 in February 2004. It was first classified as a tropical disturbance on February 21 between Vanuatu and Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...

. The system tracked northwestward, gradually organizing and intensifying. After attaining tropical storm status on February 23, Ivy strengthened more quickly as it turned southwestward toward Vanuatu. It attained peak winds of 165 km/h (105 mph) while moving over Vanuatu, making it an intense Category 4 cyclone on the Australian Region Tropical Cyclone Intensity Scale. By the time it passed through Vanuatu, Ivy had turned southeastward, and it gradually weakened while accelerating. After becoming extratropical
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...

 on February 28, it passed just east of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and eventually dissipated on March 2.

The third significant cyclone in 14 months to affect the region, Ivy produced heavy rainfall and high winds in Vanuatu. Due to advanced warning, only two people were killed, and several people were injured. The high winds damaged about 11,000 houses, leaving many people homeless. The cyclone passed very close to the Vanuatu capital city of Port Vila
Port Vila
Port Vila is the capital and largest city of Vanuatu. Situated on the south coast of the island of Efate, in Shefa Province, the city population at last was 29,356, an increase of 55% on the previous census result . This suggests a 2007 population of about 40,000 or around 65% of the province's...

, forcing the evacuation of about 2,000 people and shutting down the main port. Cyclone Ivy also affected the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

 and New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

 with rainfall, and later it produced high waves in New Zealand that killed two people. Because of its severe damage on Vanuatu, the name Ivy was retired following its usage.

Meteorological history

In the middle of February 2004, a monsoon trough
Monsoon trough
The monsoon trough is that portion of the Intertropical Convergence Zone which extends into or through a monsoon circulation, as depicted by a line on a weather map showing the locations of minimum sea level pressure, and as such, is a convergence zone between the wind patterns of the southern and...

 formed in the southwest Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 during the middle of a Madden–Julian oscillation pulse. A low pressure area
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...

 developed along the trough, and the Fiji Meteorological Service (FMS) designated it Tropical Disturbance 5F on February 21 about halfway between Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...

 and Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...

. Initially, the system was moving little and had a circulation
Atmospheric circulation
Atmospheric circulation is the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth....

 that was detached from the primary area of convection. On February 22 after the thunderstorms increased, the Joint Typhoon Warning Center (JTWC) initiated advisories on the disturbance with the designation Tropical Cyclone 13P. Shortly thereafter, the FMS reported that the disturbance developed into a tropical depression, although the convection was transient and displaced from the circulation. The system tracked west-northwestward, due to a ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....

 located to its south. With low wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...

 and good outflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...

, the system gradually organized, with the circulation becoming situated underneath the convection. At 0300 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...

 on February 23, the FMS upgraded it to a tropical cyclone and gave it the name Ivy while the storm was about 510 km (315 mi) northeast of Port Vila
Port Vila
Port Vila is the capital and largest city of Vanuatu. Situated on the south coast of the island of Efate, in Shefa Province, the city population at last was 29,356, an increase of 55% on the previous census result . This suggests a 2007 population of about 40,000 or around 65% of the province's...

, Vanuatu.

After being named, Ivy quickly intensified after its convection was drawn into the circulation. Late on February 23, the JTWC upgraded Ivy to the equivalent of a Category 1 hurricane on the Saffir-Simpson scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...

, and the FMS followed suit the following day by upgrading Ivy to a severe tropical cyclone as continued favorable conditions allowed for rapid deepening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...

. On February 24 the cyclone began a turn to the southwest as it moved around the ridge, and the next day it turned to the south toward Vanuatu as an approaching shortwave trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...

 passed to the south and created a weakness in the ridge. A nearby upper-level low temporarily cut off outflow, although once it moved further away the low enhanced ventilation. Strengthening continued and, late on February 25, the FMS reported that Ivy attained peak 10–minute sustained winds of 165 km/h (105 mph) over the Vanuatu archipelago; this made it a Category 4 on the Australian Region Tropical Cyclone Intensity Scale. Around the same time, the JTWC estimated peak 1–minute sustained winds of 195 km/h (120 mph), after a 19 km (12 mi) eye
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...

 developed.

After passing slowly through Vanuatu, Ivy began accelerating to the southeast and its eye passed very close to the capital city of Port Vila, after moving over the island of Epi
Epi (island)
Epi is the name of an island in Vanuatu, at the north end of the Shepherd Islands. It is in Shefa Province. It is long northwest-southeast, and wide, with an area of . Its shoreline measures 130 km...

. As the cyclone moved away from the island group, it underwent an eyewall replacement cycle. In addition, the combination of cooler water temperatures, greater wind shear, less outflow, and land interaction with Vanuatu caused gradual weakening. Late on February 27, Ivy entered the area of warning responsibility of the Wellington Regional Specialized Meteorological Center
Regional Specialized Meteorological Center
A Regional Specialized Meteorological Centre is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as part of the World Weather Watch.-Tropical...

. The convection rapidly diminished and left the circulation exposed, and Ivy transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...

 on February 28. It remained strong and maintained a well-defined circulation as it passed just east of East Cape
East Cape
East Cape is the easternmost point of the main islands of New Zealand. It is located to the north of Gisborne in the northeast of the North Island....

, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. Continuing southeastward, the extratropical remnants crossed the International Dateline on February 29, and Ivy dissipated about 1800 km (1100 mi) southeast of New Zealand on March 2.

Preparations and impact

While Ivy was reaching peak intensity, it passed through Vanuatu, becoming the third major cyclone in 14 months to affect the region, after Cyclone Zoe
Cyclone Zoe
Severe Tropical Cyclone Zoe was the most intense tropical cyclone recorded in the Southern Hemisphere.-Meteorological history:...

 and Cyclone Gina. Its threat prompted over 2,000 people in Port Vila to evacuate. While Ivy moved through the country, a station on Anatom
Anatom
Anatom is the southernmost island of Vanuatu. It is in the province of Tafea. The largest village is Anelghowhat , on the south side. The island is 159.2 km² in size...

 island recorded winds of 130 km/h (80 mph), which were the highest sustained winds observed in the nation. In addition, the cyclone dropped heavy rainfall, reaching 254.4 mm (10 in) at Bauerfield International Airport
Bauerfield International Airport
Bauerfield International Airport is an airport located in Port Vila, Vanuatu. The airport is relatively small in size, but its runway has the capability and length to accept jets up to the Boeing 767. It serves as the hub for Vanuatu's flag carrier airline, Air Vanuatu.-Overview:The airport was...

 in Port Vila. The central area of deep convection moved across every island in the archipelago.

As the cyclone moved through Vanuatu, it cut off communications between the various islands, and also knocked Radio Vanuatu offline. Overall there was widespread moderate damage, with small areas of heavier damage. The cyclone affected more than 54,000 people – about 25% of the population – on various islands, including Paama
Paama
Paama is a small island in the Malampa Province, Vanuatu. The island is about 8 km from north to south and only 5 km or so at its widest point. The island is dominated by hills, rising to a height of around 550 m in the north...

, Epi
Epi (island)
Epi is the name of an island in Vanuatu, at the north end of the Shepherd Islands. It is in Shefa Province. It is long northwest-southeast, and wide, with an area of . Its shoreline measures 130 km...

, Ambrym
Ambrym
Ambrym is a volcanic island in the archipelago of Vanuatu . It is well known for its highly active volcanic activity that includes lava lake formation.-Etymology:...

, eastern Malekula, northern Aoba
Aoba Island
Aoba, also known as Ambae or Leper's Island, is an island in the South Pacific island nation of Vanuatu, located near . Ambae has a population of less than 10,000, divided into 3-4 discernible language groups...

, and northern Maewo
Maewo
Maewo is an island in Vanuatu in Penama province, 105 km to the east of Espiritu Santo. It is 47 km long, and 6 km wide, with an area of 269 km². Its highest point is 795 m above sea level...

. On Ambrym island, the winds wrecked the roofs of houses and downed trees and vegetables. Overall, about 11,000 houses were damaged, and a large proportion of the 24,000 people in Ivy's path became homeless due to the destruction of their houses, with many buildings made of iron and bamboo wrecked. In addition, the winds downed trees and power lines.

Heavy damage occurred in the capital city of Port Vila, where flooding washed out small bridges. Strong waves wrecked the main port there and also capsized two boats. High winds downed trees and blocked roads across the capital, with 70% of the nation's roads affected. Several people were injured due to flying debris, and one person was severely injured due to the storm. The high winds affected 80% of the nation's food crops, including the loss of much of the mango and banana crops as well as the ruination of about 75% of the coconut and cocoa crops. The latter loss was significant due to its status as a cash crop. The cyclone damaged 90% of the water facilities across the archipelago. It also damaged about 60% of the health centers, as well as 112 schools, some of which were completely destroyed. Monetary damage was estimated at VT427.6 million (2004 VUV
Vanuatu vatu
The vatu is the currency of Vanuatu.The vatu has no subdivisions.-History:The vatu was introduced in 1982, after independence, to replace the New Hebrides franc at par...

, $3.8 million 2004 USD). Due to advanced warning, there were only two deaths in Vanuatu, including one when a landslide killed a woman on Malakula
Malakula
Malakula Island , also spelled Malekula, is the second-largest island in the nation of Vanuatu, in the Pacific Ocean region of Melanesia...

 island.

In addition to affecting Vanuatu, Ivy produced heavy rainfall in Tikopia
Tikopia
Tikopia is a small and high island in the southwestern Pacific Ocean. Covering an area of 5 km² , the island is the remnant of an extinct volcano. Its highest point, Mt. Reani, reaches an elevation of 380 m above sea level. Lake Te Roto covers an old volcanic crater which is 80 m...

 and Anuta
Anuta
Anuta is a small high island in the southeastern part of the Solomon Islands province of Temotu, the smallest permanently inhabited isolated Polynesian island.-Description:...

, two small islands in the southeastern Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

. Later, intense rainbands spread across the Loyalty Islands
Loyalty Islands
The Loyalty Islands are an archipelago in the Pacific. They are part of the French territory of New Caledonia, whose mainland is away. They form the Loyalty Islands Province , one of the three provinces of New Caledonia...

 in New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

. Along the Bay of Plenty
Bay of Plenty
The Bay of Plenty , often abbreviated to BOP, is a region in the North Island of New Zealand situated around the body of water of the same name...

 in New Zealand, the extratropical remnants of Ivy produced high waves that killed two people in Whakatane
Whakatane
Whakatane is a town in the eastern Bay of Plenty Region, in the North Island of New Zealand, and is the seat of the Bay of Plenty Regional Council. Whakatane is 90 km east of Tauranga and 89 km north-east of Rotorua, at the mouth of the Whakatane River.The town has a population of , with...

. The storm produced a 1 in 10 year
Return period
A return period also known as a recurrence interval is an estimate of the interval of time between events like an earthquake, flood or river discharge flow of a certain intensity or size. It is a statistical measurement denoting the average recurrence interval over an extended period of time, and...

 storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...

 as it passed the country that peaked at 1.04 m (3.4 ft) at Omaio. The surge, in combination with waves, reached about 5 m (16.4 ft) at Papamoa
Papamoa
Papamoa is the largest suburb of Tauranga in the Bay of Plenty region on the northeastern coast of the North Island of New Zealand....

, based on the position of debris on the beach. Wind gusts reached 79.7 km/h (49.5 mph) at the Whakatane Airport
Whakatane Airport
-External links:*...

, and the combination of winds and waves produced beach erosion along the coast.

Aftermath

The local Red Cross
International Red Cross and Red Crescent Movement
The International Red Cross and Red Crescent Movement is an international humanitarian movement with approximately 97 million volunteers, members and staff worldwide which was founded to protect human life and health, to ensure respect for all human beings, and to prevent and alleviate human...

 offices in Port Vila and Luganville
Luganville
Luganville, called "Santo" by people from Vanuatu's northern islands who use Luganville as their big city, and called "Kanal" by rural residents of the large island of Espiritu Santo, is the second largest city in Vanuatu. The population is .Luganville is one of Vanuatu's busiest ports,...

 prepared general relief supplies before the storm's arrival, including tents, tool kits, and first aid units. By four days after the cyclone's passage, the main wharf in Port Vila was re-opened and the two sunken boats were removed. Additionally, the evacuees were allowed to return to their homes, and communications between the various islands were restored. The Red Cross distributed various relief supplies to the affected citizens, including candles, matches, water, and blankets. By about two weeks after the storm, about 30,000 household relief packages were distributed. The Vanuatu government allocated VT25 million (2004 VUV, $236,000 2004 USD) for the affected citizens. Overall, the cyclone severely affected the daily lives of the Vanuatu citizens. On Tanna island, the cyclone's passage produced a malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

 outbreak.

In the immediate aftermath, the New Zealand Red Cross provided $10,000 (2004 NZD
New Zealand dollar
The New Zealand dollar is the currency of New Zealand. It also circulates in the Cook Islands , Niue, Tokelau, and the Pitcairn Islands. It is divided into 100 cents....

) for essential relief supplies. In addition, the New Zealand government provided $70,000 for assistance in the most affected areas, after the country's Air Force
Royal New Zealand Air Force
The Royal New Zealand Air Force is the air arm of the New Zealand Defence Force...

 dispatched a plane over Vanuatu to determine the extent of damage. The Government of Australia
Government of Australia
The Commonwealth of Australia is a federal constitutional monarchy under a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement among six self-governing British colonies, which became the six states...

 similarly sent a helicopter reconnaissance mission to determine damage, as well as two planes with $200,000 (2004 AUD
Australian dollar
The Australian dollar is the currency of the Commonwealth of Australia, including Christmas Island, Cocos Islands, and Norfolk Island, as well as the independent Pacific Island states of Kiribati, Nauru and Tuvalu...

) in relief supplies, including 2,400 tarps
Tarpaulin
A tarpaulin, colloquially tarp, is a large sheet of strong, flexible, water-resistant or waterproof material, often cloth such as canvas or polyester coated with urethane, or made of plastics such as polyethylene. In some places such as Australia, and in military slang, a tarp may be known as a...

, 2,600 water containers, and 5,200 packets of water purification tablets. The French government also sent a helicopter and assistance as per the 1992 FRANZ Agreement between New Zealand, Australia, and France.

Due to the severity of damage wrought by the cyclone, the World Meteorological Organization
World Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...

 retired the name Ivy following its usage and replaced it with Irene. Ivy was retired along with earlier Cyclone Heta; the two were the only named storms to form within the basin that season.

External links

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