Cyclone Wilma (2011)
Encyclopedia
Severe Tropical Cyclone Wilma (RSMC Nadi designation 06F, JTWC designation 08P) was the first tropical cyclone on record to hit New Zealand as a tropical cyclone. Forming out of a trough
of low pressure
on January 19 to the northwest of Fiji
, Cyclone Wilma initially tracked eastward towards the Samoan Islands
. On January 22, the system took a sharp southward turn, bringing its centre directly over American Samoa
the following day. After turning towards the southwest and accelerating, Wilma steadily intensified into a severe tropical cyclone before striking Tonga
. The storm reached its peak intensity on January 26 as a Category 4 cyclone with winds of 185 km/h (115 mph) and a barometric pressure of 930 mbar
(hPa
; 27.46 inHg). Gradually re-curving towards the southeast, Wilma weakened quickly as it moved over cooler sea surface temperatures; by January 28, it was downgraded to a tropical cyclone. Later that day, the storm brushed the North Island
of New Zealand
before transitioning into an extratropical cyclone
.
Throughout Wilma's path, three countries were affected, with New Zealand experiencing the most severe damage. At least three fatalities in American Samoa have been blamed on the storm, two from flooding and one from high seas. In Tonga, "major damage" was reported across the Ha'apai Islands
. In New Zealand, several homes were destroyed by the storm and hundreds of people were evacuated. However, there were no reports of fatalities. Torrential rain in the country, exceeding 280 mm (11 in) in some places, triggered 50-year flood events and isolated towns.
(JTWC) started monitoring the system as Tropical Cyclone '08P'. Later the same day, RSMC Nadi upgraded Tropical Depression 06F to a tropical cyclone and named it 'Wilma'. Early on January 24, RSMC Nadi further upgraded Wilma to a Category 2 Tropical Cyclone. Late on the same day, RSMC Nadi reported that Wilma had intensified into a Category 3 Severe Tropical Cyclone. Wilma Continued to strengthen and January 26, the RSMC Nadi upgraded it into a Category 4 Severe Tropical Cyclone. Early on January 27, Wilma entered TCWC Wellington's area of responsibility. A few hours later, TCWC Wellington took full responsibility of Wilma, and downgraded it into a Category 3 Severe Tropical Cyclone. Wilma Continued to weaken and TCWC Wellington further downgraded it into a tropical cyclone. On January 28, the JTWC, issuing their final warning, reported that the system took a southeast curve along the coast of North Island, New Zealand and started becoming extratropical. A few hours later, the TCWC Wellington, downgraded it into a low, no longer considering it tropical.
, in which more than 100 perished, the American Samoan Government ensured that residents were aware of Cyclone Wilma several days prior to its arrival. Many people boarded up their homes and Homeland Security
was on standby in case of evacuations. As a precautionary measure, ten shelters were also opened on the island.
On January 23, Wilma passed directly over American Samoa, bringing winds in excess of 95 km/h (60 mph). These winds downed numerous trees and power lines, leaving several towns and cities without electricity. Several structures also had their roofs blown off. Heavy rains triggered a few landslides but overall damage was light. With that, the Pago Pago International Airport
was closed and the American Samoa Governor, Togiola Tulafono
ordered local government agencies to help those in need. Wilma caused severe damage to the StarKist Samoa tuna cannery which was then shut down for a week. Across the region, three fatalities due to drowning were blamed on the storm. One of these was a child who was swept away by a swollen river while he was playing near it.
In the days after Wilma's passage, health officials warned residents to stay away from standing water as it may have been contaminated to prevent the spread of water-borne diseases. Following preliminary assessments of damage, Governor Tulafono stated that there was sufficient losses to warrant an emergency declaration from President Barack Obama
. However, he also requested that a second, in-depth report of the situation be made to better determine how to move forward; the second assessment was set to start on January 27. According to the Federal Emergency Management Agency
, power and water supplies were restored to all areas by January 25 and the airport was set to reopen that day. Harbours were to remain closed for several more days as debris was being cleared from coastal waters.
and Lau islands
. On the morning of January 25, Wilma blew over Tonga as a severe tropical cyclone. Major damage was reported in the Ha’apai Islands of Tonga
. Wilma also disrupted New Zealand Foreign Minister, Murray McCully
's trip to Tonga. Throughout Tonga, damage amounted to $3 million.
on January 29, as a Category 2 Tropical Cyclone. In combination with previous flooding expected to be worsened by Wilma, officials in New Zealand evacuated numerous towns in the Thames-Coromandel District
. At least 70 people sought refuge in public shelters during the storm.
As Cyclone Wilma brushed the North Island, it brought torrential rains to much of the region, with several areas recording 200 mm (7.9 in) during a 24 hour span. One station recorded 280 mm (11 in) in 12–14 hours. With this, several areas neared record-breaking rainfall totals for the month of January. These rains, in combination with heavy rains a week prior, caused several rivers to swell. One river, the Whakatane
, was expected to reach levels seen in 50-year flood events. Large amounts of debris was reported to be flowing down rivers into the ocean. High winds accompanying these rains caused significant damage as well; several homes were destroyed and electricity was cut off to many towns and cities as power lines were felled. Numerous roads across the island were shut down due to treacherous conditions. Two rural towns, Waimana and Ruatoki Valley, were isolated by flooding as high water covered all roads leading to and from the areas. In parts of the Coromandel Peninsula
, sewage treatment plants were overwhelmed by the amount of rain and began spilling raw sewage into nearby communities as well as Whangamata harbour. Along the slopes of Mount Maunganui
, campers were forced to evacuate in the middle of the night as flood waters began to threaten their rest areas. Several landslides were also reported during the passage of Wilma, cutting off roads and damaging homes. On Waiheke Island
, two residents managed to escape their cottage, after the family dog began barking outside, before the hill it was situated on gave way, destroying their house.
Throughout New Zealand, damage from Wilma was at least NZ$25 million (US$19 million). While other cyclones have weakened and turned into extratropical storms that then hit New Zealand, Cyclone Wilma is the first known to hit New Zealand as a tropical cyclone.
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...
of low pressure
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...
on January 19 to the northwest of 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...
, Cyclone Wilma initially tracked eastward towards the Samoan Islands
Samoan Islands
The Samoan Islands or Samoa Islands is an archipelago covering in the central South Pacific, forming part of Polynesia and the wider region of Oceania...
. On January 22, the system took a sharp southward turn, bringing its centre directly over American Samoa
American Samoa
American Samoa is an unincorporated territory of the United States located in the South Pacific Ocean, southeast of the sovereign state of Samoa...
the following day. After turning towards the southwest and accelerating, Wilma steadily intensified into a severe tropical cyclone before striking Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
. The storm reached its peak intensity on January 26 as a Category 4 cyclone with winds of 185 km/h (115 mph) and a barometric pressure of 930 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(hPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
; 27.46 inHg). Gradually re-curving towards the southeast, Wilma weakened quickly as it moved over cooler sea surface temperatures; by January 28, it was downgraded to a tropical cyclone. Later that day, the storm brushed the North Island
North Island
The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...
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...
before transitioning 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...
.
Throughout Wilma's path, three countries were affected, with New Zealand experiencing the most severe damage. At least three fatalities in American Samoa have been blamed on the storm, two from flooding and one from high seas. In Tonga, "major damage" was reported across the Ha'apai Islands
Ha'apai
Haapai is a group of islands, islets, reefs and shoals in the central part of the Kingdom of Tonga, with the Tongatapu group to the south and the Vavau group to the north. Seventeen of the Haapai islands are populated....
. In New Zealand, several homes were destroyed by the storm and hundreds of people were evacuated. However, there were no reports of fatalities. Torrential rain in the country, exceeding 280 mm (11 in) in some places, triggered 50-year flood events and isolated towns.
Meteorological history
Early on January 19, RSMC Nadi reported that Tropical Disturbance 06F had developed within a trough of low pressure about 665 km (413.2 mi) to the northeast of Nadi, Fiji. During that day convection surrounding the disturbance gradually became more organized before early the next day, RSMC Nadi reported that it had intensified into a tropical depression. On January 22, The Joint Typhoon Warning CenterJoint 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...
(JTWC) started monitoring the system as Tropical Cyclone '08P'. Later the same day, RSMC Nadi upgraded Tropical Depression 06F to a tropical cyclone and named it 'Wilma'. Early on January 24, RSMC Nadi further upgraded Wilma to a Category 2 Tropical Cyclone. Late on the same day, RSMC Nadi reported that Wilma had intensified into a Category 3 Severe Tropical Cyclone. Wilma Continued to strengthen and January 26, the RSMC Nadi upgraded it into a Category 4 Severe Tropical Cyclone. Early on January 27, Wilma entered TCWC Wellington's area of responsibility. A few hours later, TCWC Wellington took full responsibility of Wilma, and downgraded it into a Category 3 Severe Tropical Cyclone. Wilma Continued to weaken and TCWC Wellington further downgraded it into a tropical cyclone. On January 28, the JTWC, issuing their final warning, reported that the system took a southeast curve along the coast of North Island, New Zealand and started becoming extratropical. A few hours later, the TCWC Wellington, downgraded it into a low, no longer considering it tropical.
Samoan Islands
Following harsh criticism for the lack of a warning siren after the 2009 Samoa earthquake2009 Samoa earthquake
The 2009 Samoa earthquake was an 8.1 Mw submarine earthquake that took place in the Samoan Islands region at 06:48:11 local time on September 29, 2009 . At a magnitude of 8.1, it was the largest earthquake of 2009....
, in which more than 100 perished, the American Samoan Government ensured that residents were aware of Cyclone Wilma several days prior to its arrival. Many people boarded up their homes and Homeland Security
Homeland security
Homeland security is an umbrella term for security efforts to protect states against terrorist activity. Specifically, is a concerted national effort to prevent terrorist attacks within the U.S., reduce America’s vulnerability to terrorism, and minimize the damage and recover from attacks that do...
was on standby in case of evacuations. As a precautionary measure, ten shelters were also opened on the island.
On January 23, Wilma passed directly over American Samoa, bringing winds in excess of 95 km/h (60 mph). These winds downed numerous trees and power lines, leaving several towns and cities without electricity. Several structures also had their roofs blown off. Heavy rains triggered a few landslides but overall damage was light. With that, the Pago Pago International Airport
Pago Pago International Airport
Pago Pago International Airport , also referred to as Tafuna Airport , Tafuna Airfield, Tafuna Airbase or Pago Pago International with airport designation PPG is a public airport located seven miles southwest of the central business district of Pago Pago, in the village and plains of Tafuna on...
was closed and the American Samoa Governor, Togiola Tulafono
Togiola Tulafono
Togiola Talalelei A. Tulafono is the Governor of American Samoa. He is a member of the Democratic Party. He had previously served as Lieutenant Governor, taking this position on January 3, 1997....
ordered local government agencies to help those in need. Wilma caused severe damage to the StarKist Samoa tuna cannery which was then shut down for a week. Across the region, three fatalities due to drowning were blamed on the storm. One of these was a child who was swept away by a swollen river while he was playing near it.
In the days after Wilma's passage, health officials warned residents to stay away from standing water as it may have been contaminated to prevent the spread of water-borne diseases. Following preliminary assessments of damage, Governor Tulafono stated that there was sufficient losses to warrant an emergency declaration from President Barack Obama
Barack Obama
Barack Hussein Obama II is the 44th and current President of the United States. He is the first African American to hold the office. Obama previously served as a United States Senator from Illinois, from January 2005 until he resigned following his victory in the 2008 presidential election.Born in...
. However, he also requested that a second, in-depth report of the situation be made to better determine how to move forward; the second assessment was set to start on January 27. According to the Federal Emergency Management Agency
Federal Emergency Management Agency
The Federal Emergency Management Agency is an agency of the United States Department of Homeland Security, initially created by Presidential Reorganization Plan No. 1 of 1978 and implemented by two Executive Orders...
, power and water supplies were restored to all areas by January 25 and the airport was set to reopen that day. Harbours were to remain closed for several more days as debris was being cleared from coastal waters.
Tonga and Lau Islands
After Wilma moved over American Samoa, a tropical cyclone alert was issued in TongaTonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
and Lau islands
Lau Islands
The Lau Islands of Fiji are situated in the southern Pacific Ocean, just east of the Koro Sea. Of this chain of about one hundred islands and islets, about thirty are inhabited...
. On the morning of January 25, Wilma blew over Tonga as a severe tropical cyclone. Major damage was reported in the Ha’apai Islands of Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
. Wilma also disrupted New Zealand Foreign Minister, Murray McCully
Murray McCully
Murray Stuart McCully is a New Zealand politician. He is a member of the National Party, and Minister of Foreign Affairs, Minister for Sport and Recreation, and Minister for the Rugby World Cup.-Early life:...
's trip to Tonga. Throughout Tonga, damage amounted to $3 million.
New Zealand
According to the media, Wilma was expected to approach the coasts of Cape ReingaCape Reinga
Cape Reinga is the northwesternmost tip of the Aupouri Peninsula, at the northern end of the North Island of New Zealand. Cape Reinga is located over 100 km north of the nearest small town of Kaitaia. State Highway 1 extends all the way to the Cape, but until 2010 was unsealed gravel road for the...
on January 29, as a Category 2 Tropical Cyclone. In combination with previous flooding expected to be worsened by Wilma, officials in New Zealand evacuated numerous towns in the Thames-Coromandel District
Thames-Coromandel District
The Thames-Coromandel District Council in the North Island of New Zealand is seated in the town of Thames. It is located in the region around the Firth of Thames and Coromandel Peninsula, to the southeast of Auckland...
. At least 70 people sought refuge in public shelters during the storm.
As Cyclone Wilma brushed the North Island, it brought torrential rains to much of the region, with several areas recording 200 mm (7.9 in) during a 24 hour span. One station recorded 280 mm (11 in) in 12–14 hours. With this, several areas neared record-breaking rainfall totals for the month of January. These rains, in combination with heavy rains a week prior, caused several rivers to swell. One river, the Whakatane
Whakatane River
The Whakatane River is a major river of the Bay of Plenty Region in the North Island of New Zealand.It flows north from near the small town of Ruatahuna through Te Urewera National Park, reaching the Bay of Plenty through the town of Whakatane. The river is 95 kilometres in length....
, was expected to reach levels seen in 50-year flood events. Large amounts of debris was reported to be flowing down rivers into the ocean. High winds accompanying these rains caused significant damage as well; several homes were destroyed and electricity was cut off to many towns and cities as power lines were felled. Numerous roads across the island were shut down due to treacherous conditions. Two rural towns, Waimana and Ruatoki Valley, were isolated by flooding as high water covered all roads leading to and from the areas. In parts of the Coromandel Peninsula
Coromandel Peninsula
The Coromandel Peninsula lies in the North Island of New Zealand. It is part of the Waikato Region and Thames-Coromandel District and extends 85 kilometres north from the western end of the Bay of Plenty, forming a natural barrier to protect the Hauraki Gulf and the Firth of Thames in the west...
, sewage treatment plants were overwhelmed by the amount of rain and began spilling raw sewage into nearby communities as well as Whangamata harbour. Along the slopes of Mount Maunganui
Mount Maunganui
Mount Maunganui is a town in the Bay of Plenty, New Zealand, located on a peninsula to the north of Tauranga. It was independent from Tauranga until the completion of the Tauranga Harbour Bridge in 1988....
, campers were forced to evacuate in the middle of the night as flood waters began to threaten their rest areas. Several landslides were also reported during the passage of Wilma, cutting off roads and damaging homes. On Waiheke Island
Waiheke Island
Waiheke Island is an island in the Hauraki Gulf of New Zealand, located about from Auckland.The island is the second-largest in the Hauraki Gulf after Great Barrier Island. It is the most populated, with nearly 8,000 permanent residents plus another estimated 3,400 who have second or holiday homes...
, two residents managed to escape their cottage, after the family dog began barking outside, before the hill it was situated on gave way, destroying their house.
Throughout New Zealand, damage from Wilma was at least NZ$25 million (US$19 million). While other cyclones have weakened and turned into extratropical storms that then hit New Zealand, Cyclone Wilma is the first known to hit New Zealand as a tropical cyclone.