Cyclone Gonu

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Super Cyclonic Storm Gonu

Super cyclonic storm (IMD)
Category 5 cyclone (SSHS)
Cyclone Gonu near peak intensity
Formed	June 1, 2007
Dissipated	June 7, 2007
Highest winds	240 km/h (150 mph) (3-minute sustained) 270 km/h (165 mph) (1-minute sustained)
Lowest pressure	920 hPa (mbar)
Fatalities	72 total
Damage	$4.2 billion (2007 USD)
Areas affected	Oman, United Arab Emirates, Pakistan, Iran
Part of the 2007 North Indian Ocean cyclone season

Cyclone Gonu (JTWC designation: 02A, also known as Super Cyclonic Storm Gonu) was the strongest tropical cyclone on record in the Arabian Sea, and tied for the strongest tropical cyclone on record in the northern Indian Ocean and was the strongest named cyclone in this basin.^[1] The second named tropical cyclone of the 2007 North Indian Ocean cyclone season, Gonu developed from a persistent area of convection in the eastern Arabian Sea on June 1. With a favorable upper-level environment and warm sea surface temperatures, it rapidly intensified to attain peak winds of 240 km/h (150 mph) on June 3, according to the India Meteorological Department. Gonu weakened after encountering dry air and cooler waters, and late on June 5 it made landfall on the eastern-most tip of Oman with winds of 150 km/h (90 mph), becoming the strongest tropical cyclone to hit the Arabian Peninsula. It then turned northward into the Gulf of Oman, and dissipated after moving ashore along southern Iran on June 7.

Intense cyclones like Gonu have been extremely rare over the Arabian Sea, as most storms in this area tend to be small and dissipate quickly.^[2] The cyclone caused about $4 billion in damage (2007 USD) and nearly 50 deaths in Oman, where the cyclone was considered the nation's worst natural disaster. Gonu dropped heavy rainfall near the eastern coastline, reaching up to 610 mm (24 inches), which caused flooding and heavy damage. In Iran, the cyclone caused 23 deaths and $215 million in damage (2007 USD). The name Gonu was contributed by the Maldives, meaning 'bag made from palm leaves' in Dhivehi, the Maldivian language.^[3]

[edit] Meteorological history

Storm path

On May 27, a widespread area of convection persisted over the southeastern Arabian Sea.^[4] By May 31, an organized tropical disturbance developed about 645 km (400 mi) south of Mumbai, India with cyclonic convection and a well-defined mid-level circulation. The disturbance initially lacked a distinct low-level circulation; instead it consisted of strong divergence along the western end of a surface trough of low pressure.^[5] A propitious upper-level environment allowed convection to improve,^[6] and late on June 1 the system developed to the extent that the India Meteorological Department (IMD) classified it a depression.^[7] It tracked westward along the southwestern periphery of a mid-level ridge over southern India. Convection continued to organize, and early on June 2 the Joint Typhoon Warning Center (JTWC) classified it Tropical Cyclone 02A about 685 km (425 mi) southwest of Mumbai.^[8]

Upon first forming, the system contended with the entrainment of dry air to the northwest of the storm, which was expected to limit intensification.^[8] The storm steadily intensified, and early on June 2 the IMD upgraded it to deep depression status.^[9] Later in the day the IMD classified the system as Cyclonic Storm Gonu about 760 km (470 mi) southwest of Mumbai, India.^[10] As a mid-latitude trough developed over Pakistan, Gonu turned to the north and northeast,^[11] though it resumed a westward track after ridging built to the north of the storm.^[12] With a solid area of intense convection, it rapidly intensified to attain severe cyclonic status early on June 3,^[13] and with good outflow the JTWC upgraded it to the equivalent of a minimal hurricane.^[14] The dry air ultimately had a smaller impact on the intensification than previously estimated. A well-defined eye developed in the center of convection, and after moving over a local increase in ocean heat content, Gonu rapidly deepened.^[15]

Late on June 3, the IMD classified the storm as Very Severe Cyclonic Storm Gonu,^[16] upon which it became the most intense cyclone on record in the Arabian Sea.^[1] With low amounts of vertical wind shear and favorable upper-level outflow, Gonu strengthened further to attain peak 1-min sustained winds of 270 km/h (165 mph)^[1] and gusts to 315 km/h (195 mph) about 285 km (175 mi) east-southeast of Masirah Island on the coast of Oman.^[17] Based on their estimate, Gonu was tied for the strongest tropical cyclone in the northern Indian Ocean, and had the highest windspeed of any cyclone in this basin.^[1] The IMD upgraded it to Super Cyclonic Storm Gonu late on June 4, with sustained winds reaching 240 km/h (150 mph) and an estimated pressure of 920 mbar.^[18] After maintaining peak winds for about nine hours, the IMD downgraded Gonu to very severe cyclonic storm status early on June 5.^[19] Its eye became cloud-filled and ragged, and the cyclone gradually weakened due to cooler water temperatures and drier air as it approached the Arabian Peninsula.^[20] Due to land interaction with Oman, the inner core of deep convection rapidly weakened, and over a period of 24 hours the intensity decreased by 95 km/h (60 mph).^[21] According to the IMD, Cyclone Gonu crossed the eastern-most tip of Oman with winds of 150 km/h (90 mph) late on June 5,^[22] making it the strongest tropical cyclone on record to strike the Arabian Peninsula.^[23] Though the winds continued to gradually decrease as it interacted with land, overall organization increased slightly in the hours prior to landfall; Gonu maintained a well-defined low-level structure with a weak eye.^[24]

After emerging into the Gulf of Oman, the cyclone briefly re-intensified slightly.^[25] However, increasing wind shear and entrainment of dry air from the Arabian Peninsula continued to remove deep convection from its eastern semicircle.^[26] On June 6, the cyclone turned to the north-northwest,^[27] and later that day the JTWC downgraded Gonu to tropical storm status.^[28] The IMD followed suit by downgrading Gonu to severe cyclonic storm status^[29] and later to cyclonic storm status early on June 7.^[30] Gonu crossed the Makran coast in Iran six hours later, and the IMD stopped issuing advisories on the cyclone.^[31]

[edit] Preparations

The Oman Chairman of the National Committee for Civil Defence remarked the nation had already developed a contingency plan, which included the activation of army and police personnel after the storm's passage. Significant damage was expected, especially in northeastern areas, along with up to 150 mm (6 in) of rainfall and very strong winds.^[32] Officials recommended citizens to evacuate from potentially affected areas,^[33] and about 7,000 people were forced to leave Masirah Island due to the threat of high surf and strong winds.^[34] Overall, more than 20,000 people evacuated to emergency shelters.^[35] A state of emergency was declared for the nation.^[33] The national weather service in Oman warned that the cyclone was expected to be worse than the destructive cyclone which hit Masirah Island in 1977.^[36] The Mina al Fahal oil terminal closed for over three days due to the threat of the storm.^[37] Omani officials closed government offices for two days, and declared a 5-day long national holiday due to the threat of the cyclone. Most businesses near the coastline were closed prior to the announcement.^[38] Authorities at the Seeb International Airport delayed all flights after 2000 UTC on June 5 due to the cyclone.^[39]

In Saudi Arabia and the United Arab Emirates, both members of OPEC, no official warnings had been issued on Gonu. The storm was not expected to disrupt oil supplies from these two nations.^[33] Oil prices rose early on June 5 because of concerns about disruptions caused by Gonu and the threat of further strikes in Nigeria, Africa's biggest producer. Crude oil for July delivery rose $1.13, or 1.7 percent, to $66.21 Monday on the New York Mercantile Exchange, the highest close since May 21. Futures touched $66.48, the highest intraday price since April 30. The contract was at $65.95 a barrel, down 26 cents, in after-hours electronic trading at 9:43 a.m. Tuesday in Singapore.^[40] Tom Kloza, chief oil analyst at the Oil Price Information Service, said he doubted the increase could really be attributed to Gonu. "I don't know if you can really attribute any of the gain to the cyclone," he said. "It's an excuse, as opposed to a reason, for the rise in prices."^[41]

In Pakistan, officials recommended fishermen to remain within 50 km (30 mi) of the coastline, due to anticipated rough waves in the open ocean.^[42] Naval authorities in the United States warned for ships to avoid the cyclone in the Arabian Sea.^[43]

The Iran Department of Meteorology declared storm warnings for the country's southeastern coastline; the agency anticipated moderate to severe precipitation and gusty winds.^[44] Prior to the arrival of the cyclone, about 40,000 people evacuated coastal areas of the country to at least 1 km (0.6 mi) inland,^[45] including around 4,000 students at the International University of Chabahar. All flights in and out of the Konarak Airport were canceled during a 48-hour period. Additionally, all hospitals in Sistan and Baluchestan Province were put on red alert.^[46] The Iran chapter of the Red Cross advanced the delivery of necessary relief supplies.^[47]

[edit] Impact

Damage in Muscat as a result of Gonu

The cyclone delayed the arrival of the Indian Ocean south-west monsoon in the Western Ghats in India.^[48]

About seven hours before passing near the northeastern Oman coastline, Cyclone Gonu began affecting the country with rough winds and heavy precipitation,^[49] with rainfall totals reaching 610 mm (24 in) near the coast.^[50] Gonu produced strong waves along much of the coastline,^[49] leaving many coastal roads flooded.^[44] Strong winds knocked out power and telephone lines across the eastern region of the country, leaving thousands isolated until the lines were repaired hours later. The cyclone caused extensive damage along the coastline, including in the city of Sur and the village of Ras al Hadd at the easternmost point of the Omani mainland.^[51] In Muscat, winds reached 100 km/h (62 mph), leaving the capital city without power. Strong waves and heavy rainfall flooded streets and some buildings. In effort to prevent electrocutions, police workers sent text messages to residents which recommended residents away from certain streets. Little damage was reported to the oil fields of the nation.^[35] The liquefied natural gas terminal in Sur, which handles 10 million tonnes of gas each year, was badly hit by the storm and could not be operated.^[52] According to the Oman News Agency, the cyclone killed 49 people in the country, with an additional 27 reported missing by four days after it struck the country.^[53] Around 20,000 people were affected,^[54] and damage in the country was estimated at around $4 billion (2007 USD), ranking it as the worst natural disaster on record in Oman.^[55]

Map showing rainfall totals around the Gulf of Oman between May 31 and June 7, 2007. The red areas show where rainfall exceeded 200 mm (8 inches).

Fierce waves pushed large amounts of water to coastal areas in Fujairah of the United Arab Emirates, forcing roads to be closed and traffic diverted. Civil defence and police were on duty to manage the road closures, while municipal workers pumped the excess water off the roads. The road connecting Kalba and Fujairah was closed due to the road being submerged by water.^[56] The waves in the coastline were reported to be 10 m (32 ft) high, which destroyed about a dozen fishing boats. About 300 boats were moved from the water or emptied of equipment,^[57] and overall damage to the port of Fujairah was reported as severe. A boat sank by the port of Fujairah, leaving its ten passengers missing.^[58]

Upon striking Iran, Gonu dropped moderate to heavy rainfall, including 74 mm (2.91 in) in the city of Chabahar.^[45] Winds reached 111 km/h (69 mph),^[35] which caused power outages and damaged some homes made of clay;^[45] the power outage led to some fires across the city of Chabahar. The rainfall flooded at least 40 houses,^[46] and resulted in the temporary closure of several major roads.^[35] Cyclone Gonu produced a storm tide of 2 m (6.5 ft) in some locations,^[59] with many homes near the coastline receiving damage.^[37] In Bandar-e-gaz, heavy rainfall overflowed a river, killing three people in a vehicle caught in the water.^[60] Flooding from the rainfall also destroyed a dam in Nikshahr County. Throughout the country, the cyclone caused 23 deaths, including 20 from drowning; damage in Iran was estimated at 2 billion (2007 IRR, $216 million 2007 USD).^[59]

[edit] Aftermath

The Seeb International Airport in Muscat, Oman reopened after three days of closure. The port of Fujairah in the United Arab Emirates reopened on June 7 after it was closed the day before.^[52] The cyclone caused little impact to oil facilities along its path, and as a result oil prices dropped over US$2 per barrel.^[61] In Oman, production of desalinated water was interrupted, as both of Oman's desalination plants failed. The first, Ghubrah, lost supplies of natural gas, halting production; while the second, Barka, sustained a damaged switchgear due to flooding. These plants provided water to Muscat's 631,000 residents and surrounding areas, triggering severe water shortages across eastern Oman. To rectify the situation, officials emptied water tanks. The water returned to near normal in five days, as the two plants returned to service. Additionally, electricians worked quickly to repair power outages.^[53] Five days after Gonu hit, utilities were restored to most of Muscat and the coastal provinces. The Omani army assisted residents in returning to their houses. Even though the Omani government did not request any international aid, the United States offered assistance through naval ships in the area. This was eventually rejected.^[50] The country lost an estimated $200 million (2007 USD) in oil exports.^[62]

After the passage of the cyclone, the Iran chapter of the Red Cross and its volunteers worked in conjunction with the military to distribute relief supplies to isolated villages using trucks and helicopters. The branch in Sistan and Baluchestan Province distributed over 10,000  blankets, 1,300 tents, 400 clothing items, 82,000 loaves of bread, and 87,000 bottles of water to affected citizens.^[47]

[edit] See also

Tropical cyclones portal

• List of most intense tropical cyclones
• Geography of Oman

[edit] References

[edit] External links

Wikimedia Commons has media related to:

Cyclone Gonu

• History of past cyclones in the Arabian Sea (IMD)
• Pictures of destruction by Cyclone Gonu (PDF)
• CIMSS Satellite Blog