Cyclone Onil
Encyclopedia
Severe Cyclonic Storm Onil (India Meteorological Department
designation: ARB 03; Joint Typhoon Warning Center
designation: 03A) was the first tropical cyclone
to be named
in the northern Indian Ocean
. Forming out of an area of convection
several hundred kilometres southwest of India on October 1, Cyclone Onil quickly attained its peak intensity on October 2 with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg). However, dry air quickly entered the system, causing it to rapidly weaken to a depression just off the coast of Gujarat, India. Over the following several days, the system took a slow, erratic track towards the south-southeast. After turning northeastward, the system made landfall
near Porbandar
on October 10 and dissipated shortly thereafter.
Throughout southeastern Pakistan and northwestern India, thousands of residents were evacuated prior to the cyclone's arrival. In these areas, the storm produced moderate to heavy rainfall, peaking at 145 mm (5.7 in) in Thatta
, Sindh
, Pakistan. These rains led to flash flooding in several areas. Nine people died in several incidents related to the storm in Karachi
. The drainage system of Hyderabad sustained significant damage, leading to several protests and demonstrations by city residents. Offshore, 300 fishermen are believed to have gone missing during the storm; no reports have confirmed their whereabouts since they disappeared.
early on September 30, 2004 situated roughly 465 km (290 mi) southwest of Mumbai, India. Satellite imagery depicted a poorly organized system with deep convection partially surrounding a low-level circulation
. Situated over warm water and within an area of moderate wind shear
, the Joint Typhoon Warning Center
(JTWC) assessed the system's chances of developing into a tropical cyclone
as "fair". Within several hours of being identified, the Indian Meteorological Department (IMD) began monitoring the system as Depression ARB 03. Despite a decrease in convection later on September 30, the IMD upgraded the cyclone to a deep depression, stating that three-minute sustained winds had reached 55 km/h (35 mph). Early the next day, organization substantially improved, prompting the JTWC to issue a Tropical Cyclone Formation Alert
. Around 0900 UTC
on October 1, the IMD upgraded the deep depression to Cyclonic Storm Onil. Upon being named, the storm became the first tropical cyclone on record to be named in the northern Indian Ocean. The WMO/ESCAP Panel agreed in May 2004 that in September, tropical cyclones in the Northern Indian Ocean attaining gale-force winds would be given names.
Later on October 1, the JTWC issued their first advisory on the storm, classifying it as Tropical Cyclone 03A. Tracking towards the northeast, Onil intensified as convection consolidated around the center of circulation. Roughly 24 hours after being named, the system attained its peak intensity as a severe cyclonic storm with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg) according to the IMD with. Upon reaching this strength, the system featured a pinhole eye
surrounded by deep convection. Additionally, Dvorak technique
intensity estimates reached 3.5, indicating a high-end tropical storm. However, the JTWC stated maximum winds to be 65 km/h (40 mph), a low-end tropical storm. As the storm neared the India
n coastline, dry air quickly entered the circulation, causing most of the convection associated with Onil to dissipate. Located within 100 km (65 mi) of land, the JTWC downgraded the system to a tropical depression and the IMD downgraded Onil to a deep depression.
On October 3, the center of Onil skimmed the coastline of northwestern India; however, the center did not cross land. Around this time, the upper-level circulation detached from the low-level circulation, further weakening the storm. Early on October 4, the JTWC stated that the system had degenerated into a non-convective remnant low pressure system. After executing a counter-clockwise loop, the depression slowly tracked south-southeastward, away from land. By October 7, the system was re-classified as a tropical depression by the JTWC as it stalled several hundred kilometres southwest of Gujarat, India. The system maintained a relatively low intensity for the following several days before making landfall near Porbandar
with winds of 45 km/h (30 mph). Within hours of moving inland, Onil dissipated early on October 10.
In southeastern Pakistan
, an estimated 6,000 people were evacuated from coastal regions prior to Cyclone Onil's arrival. Port officials warned fishermen not to venture out during the storm due to rough seas. Cyclone Onil brought moderate to heavy rainfall and gusty winds. A maximum of 145 mm (5.7 in) of rain fell in Thatta
, Sindh
between October 2 and 3. In Hyderabad, heavy rains amounting to 98 mm (3.9 in) caused a 10 ft (3 m) section of a drainage system to collapse, prompting the evacuation of several hundred residents. Throughout Sindh, an estimated 607 square kilometres (234.4 sq mi) of land was inundated by flood waters, destroying roughly 70% of the cotton crop. In the city of Karachi
, nine people were killed in various incidents related to the storm at least 35 mi/h winds were reported. Two people were killed after being electrocuted by a downed power line outside their home. Many streets in the city were flooded and power lines were downed. Another one of these people died while trying to clear a drain near her house when a wall collapsed on her. Offshore, 163 fishermen were reported to be missing after being caught in the storm. However, reports from Pakistani officials stated that at least 300 fishermen were missing. In other areas, power was lost for more than 48 hours after Onil moved through the region. Around Karo Gongro, 100 people were stranded along a major roadway after flash flooding struck the area.
In the wake of the storm, Pakistani officials set up 26 relief camps where residents were offered food and shelter. Roughly 3,000 people sought refuge in these shelters. Mobile units were also set up by the District Health Department to minimize the impacts of any post-storm diseases. On October 3, Imtiaz Ahmed Shaikh expressed his grief over the damage caused by Cyclonic Storm Onil and stated that he would be touring the affected region within the following days. At least 40 million Pakistani rupee
($469,000 USD
) was allocated in relief funds by Sindh Minster Syed Papoo Shah. On October 4, port officials stated that it was safe for fishermen to resume their activities in the Arabian Sea. Later that day, a rain emergency was declared for Hyderabad and emergency shelters were set up in the city. All officers in the Hyderabad Development Authority who were initially put on leave ahead of the cyclone were told to resume work to assist in clearing drainage systems. Several days after the storm, reports indicated that there were more than 300 instances where the city's drainage system collapsed across the area, resulting in standing water in many structures. Residents in these areas, frustrated by the lack of quick action by the government, began holding protests about the flooding. In response to these protests, Shaukat Hayat Bhutto suspended Assistant Engineer Sewage manager, Qamar Memon, for his negligence on draining flood waters.
India Meteorological Department
The India Meteorological Department , also referred to as the Met Office, is an agency of the Ministry of Earth Sciences of the Government of India. It is the principal agency responsible for meteorological observations, weather forecasting and seismology...
designation: ARB 03; 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: 03A) was the first 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...
to be named
Tropical cyclone naming
Tropical cyclones have officially been named since 1945 and are named for a variety of reasons, which include to facilitate communications between forecasters and the public when forecasts, watches, and warnings are issued. Names also reduce confusion about what storm is being described, as more...
in the northern Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
. Forming out of an area of convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
several hundred kilometres southwest of India on October 1, Cyclone Onil quickly attained its peak intensity on October 2 with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg). However, dry air quickly entered the system, causing it to rapidly weaken to a depression just off the coast of Gujarat, India. Over the following several days, the system took a slow, erratic track towards the south-southeast. After turning northeastward, the system made landfall
Landfall (meteorology)
Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...
near Porbandar
Porbandar
Porbandar is a coastal city in the Indian state of Gujarat, perhaps best known for being the birthplace of Mahatma Gandhi and Sudama...
on October 10 and dissipated shortly thereafter.
Throughout southeastern Pakistan and northwestern India, thousands of residents were evacuated prior to the cyclone's arrival. In these areas, the storm produced moderate to heavy rainfall, peaking at 145 mm (5.7 in) in Thatta
Thatta
Thatta is a historic town of 220,000 inhabitants in the Sindh province of Pakistan, near Lake Keenjhar, the largest freshwater lake in the country. Thatta's major monuments especially its necropolis at Makli are listed among the World Heritage Sites. The Shah Jahan Mosque is also listed...
, Sindh
Sindh
Sindh historically referred to as Ba'ab-ul-Islam , is one of the four provinces of Pakistan and historically is home to the Sindhi people. It is also locally known as the "Mehran". Though Muslims form the largest religious group in Sindh, a good number of Christians, Zoroastrians and Hindus can...
, Pakistan. These rains led to flash flooding in several areas. Nine people died in several incidents related to the storm in Karachi
Karachi
Karachi is the largest city, main seaport and the main financial centre of Pakistan, as well as the capital of the province of Sindh. The city has an estimated population of 13 to 15 million, while the total metropolitan area has a population of over 18 million...
. The drainage system of Hyderabad sustained significant damage, leading to several protests and demonstrations by city residents. Offshore, 300 fishermen are believed to have gone missing during the storm; no reports have confirmed their whereabouts since they disappeared.
Meteorological history
Severe Cyclonic Storm Onil was first identified as an area of convectionAtmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
early on September 30, 2004 situated roughly 465 km (290 mi) southwest of Mumbai, India. Satellite imagery depicted a poorly organized system with deep convection partially surrounding a low-level circulation
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...
. Situated over warm water and within an area of moderate 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...
, the 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...
(JTWC) assessed the system's chances of developing into 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...
as "fair". Within several hours of being identified, the Indian Meteorological Department (IMD) began monitoring the system as Depression ARB 03. Despite a decrease in convection later on September 30, the IMD upgraded the cyclone to a deep depression, stating that three-minute sustained winds had reached 55 km/h (35 mph). Early the next day, organization substantially improved, prompting the JTWC to issue a Tropical Cyclone Formation Alert
Tropical Cyclone Formation Alert
A Tropical Cyclone Formation Alert is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Naval Maritime Forecast Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming from a tropical disturbance that has been...
. Around 0900 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 October 1, the IMD upgraded the deep depression to Cyclonic Storm Onil. Upon being named, the storm became the first tropical cyclone on record to be named in the northern Indian Ocean. The WMO/ESCAP Panel agreed in May 2004 that in September, tropical cyclones in the Northern Indian Ocean attaining gale-force winds would be given names.
Later on October 1, the JTWC issued their first advisory on the storm, classifying it as Tropical Cyclone 03A. Tracking towards the northeast, Onil intensified as convection consolidated around the center of circulation. Roughly 24 hours after being named, the system attained its peak intensity as a severe cyclonic storm with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg) according to the IMD with. Upon reaching this strength, the system featured a pinhole 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...
surrounded by deep convection. Additionally, Dvorak technique
Dvorak technique
The Dvorak technique is a widely used system to subjectively estimate tropical cyclone intensity based solely on visible and infrared satellite images. Several agencies issue Dvorak intensity numbers for cyclones of sufficient intensity...
intensity estimates reached 3.5, indicating a high-end tropical storm. However, the JTWC stated maximum winds to be 65 km/h (40 mph), a low-end tropical storm. As the storm neared the India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n coastline, dry air quickly entered the circulation, causing most of the convection associated with Onil to dissipate. Located within 100 km (65 mi) of land, the JTWC downgraded the system to a tropical depression and the IMD downgraded Onil to a deep depression.
On October 3, the center of Onil skimmed the coastline of northwestern India; however, the center did not cross land. Around this time, the upper-level circulation detached from the low-level circulation, further weakening the storm. Early on October 4, the JTWC stated that the system had degenerated into a non-convective remnant low pressure system. After executing a counter-clockwise loop, the depression slowly tracked south-southeastward, away from land. By October 7, the system was re-classified as a tropical depression by the JTWC as it stalled several hundred kilometres southwest of Gujarat, India. The system maintained a relatively low intensity for the following several days before making landfall near Porbandar
Porbandar
Porbandar is a coastal city in the Indian state of Gujarat, perhaps best known for being the birthplace of Mahatma Gandhi and Sudama...
with winds of 45 km/h (30 mph). Within hours of moving inland, Onil dissipated early on October 10.
Impact and aftermath
In northwestern India, thousands of residents were evacuated in fears of Onil striking the region. According to one of the evacuated residents, this was the seventh evacuation due to a cyclone in the area since 1999. On October 10, the storm's remnants brought light to moderate rainfall in India; there was no known rainfall amount exceeding 100 mm (3.9 in) throughout the region.In southeastern Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
, an estimated 6,000 people were evacuated from coastal regions prior to Cyclone Onil's arrival. Port officials warned fishermen not to venture out during the storm due to rough seas. Cyclone Onil brought moderate to heavy rainfall and gusty winds. A maximum of 145 mm (5.7 in) of rain fell in Thatta
Thatta
Thatta is a historic town of 220,000 inhabitants in the Sindh province of Pakistan, near Lake Keenjhar, the largest freshwater lake in the country. Thatta's major monuments especially its necropolis at Makli are listed among the World Heritage Sites. The Shah Jahan Mosque is also listed...
, Sindh
Sindh
Sindh historically referred to as Ba'ab-ul-Islam , is one of the four provinces of Pakistan and historically is home to the Sindhi people. It is also locally known as the "Mehran". Though Muslims form the largest religious group in Sindh, a good number of Christians, Zoroastrians and Hindus can...
between October 2 and 3. In Hyderabad, heavy rains amounting to 98 mm (3.9 in) caused a 10 ft (3 m) section of a drainage system to collapse, prompting the evacuation of several hundred residents. Throughout Sindh, an estimated 607 square kilometres (234.4 sq mi) of land was inundated by flood waters, destroying roughly 70% of the cotton crop. In the city of Karachi
Karachi
Karachi is the largest city, main seaport and the main financial centre of Pakistan, as well as the capital of the province of Sindh. The city has an estimated population of 13 to 15 million, while the total metropolitan area has a population of over 18 million...
, nine people were killed in various incidents related to the storm at least 35 mi/h winds were reported. Two people were killed after being electrocuted by a downed power line outside their home. Many streets in the city were flooded and power lines were downed. Another one of these people died while trying to clear a drain near her house when a wall collapsed on her. Offshore, 163 fishermen were reported to be missing after being caught in the storm. However, reports from Pakistani officials stated that at least 300 fishermen were missing. In other areas, power was lost for more than 48 hours after Onil moved through the region. Around Karo Gongro, 100 people were stranded along a major roadway after flash flooding struck the area.
In the wake of the storm, Pakistani officials set up 26 relief camps where residents were offered food and shelter. Roughly 3,000 people sought refuge in these shelters. Mobile units were also set up by the District Health Department to minimize the impacts of any post-storm diseases. On October 3, Imtiaz Ahmed Shaikh expressed his grief over the damage caused by Cyclonic Storm Onil and stated that he would be touring the affected region within the following days. At least 40 million Pakistani rupee
Pakistani rupee
The rupee is the currency of Pakistan. The issuance of the currency is controlled by the State Bank of Pakistan, the central bank of the country. The most commonly used symbol for the rupee is Rs, used on receipts when purchasing goods and services. In Pakistan, the rupee is referred to as the...
($469,000 USD
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
) was allocated in relief funds by Sindh Minster Syed Papoo Shah. On October 4, port officials stated that it was safe for fishermen to resume their activities in the Arabian Sea. Later that day, a rain emergency was declared for Hyderabad and emergency shelters were set up in the city. All officers in the Hyderabad Development Authority who were initially put on leave ahead of the cyclone were told to resume work to assist in clearing drainage systems. Several days after the storm, reports indicated that there were more than 300 instances where the city's drainage system collapsed across the area, resulting in standing water in many structures. Residents in these areas, frustrated by the lack of quick action by the government, began holding protests about the flooding. In response to these protests, Shaukat Hayat Bhutto suspended Assistant Engineer Sewage manager, Qamar Memon, for his negligence on draining flood waters.
See also
- 2004 North Indian Ocean cyclone season2004 North Indian Ocean cyclone seasonThe 2004 North Indian Ocean cyclone season had no bounds, but cyclones tend to form between April and December, with peaks in May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.-Season summary:In 2004, RSMC New...
- List of wettest known tropical cyclones in Pakistan