North Indian Ocean cyclone in 2020
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Super Cyclonic Storm Amphan ( ) was an extremely powerful and catastrophic tropical cyclone that caused widespread damage in Eastern India, specifically in West Bengal and Odisha, and in Bangladesh, in May 2020. It was the strongest tropical cyclone to strike the Ganges Delta. It was a rare cyclone that lashed northern Bangladesh from Rajshahi to Rangpur in the early hours of 21 May with strong winds. It caused severe damage to mango production of Rajshahi and Rangpur. It was also the fourth super cyclone that hit West Bengal and Kolkata since 2015 as well as being one of the strongest storms to impact the area. Causing over US$15 billion of damage, Amphan is also the costliest cyclone ever recorded in the North Indian Ocean, surpassing the record held by Nargis of 2008.
The first tropical cyclone of the 2020 North Indian Ocean cyclone season, Amphan originated from a low-pressure area persisting a couple of hundred miles (300 km) east of Colombo, Sri Lanka, on 13 May 2020. Tracking northeastward, the disturbance organized over exceptionally warm sea surface temperatures; the Joint Typhoon Warning Center (JTWC) upgraded the system to a tropical depression on 15 May while the India Meteorological Department (IMD) followed suit the following day. On 17 May, Amphan underwent rapid intensification and became an extremely severe cyclonic storm within 12 hours.
On 18 May, at approximately 12:00 UTC, Amphan reached its peak intensity with 3-minute sustained wind speeds of , 1-minute sustained wind speeds of , and a minimum central barometric pressure of . The storm began an eyewall replacement cycle shortly after it reached its peak intensity, but the continued effects of dry air and wind shear disrupted this process and caused Amphan to gradually weaken as it paralleled the eastern coastline of India. On 20 May, 12:00 UTC, the cyclone made landfall in West Bengal. At the time, the JTWC estimated Amphan's 1-minute sustained winds to be . Amphan rapidly weakened once inland and dissipated shortly thereafter.
Coastal areas in West Bengal comprising West Midnapore, East Midnapore, North 24 Parganas, South 24 Parganas, Kolkata, Hooghly and Howrah were heavily affected by the cyclone. It also caused significant destruction in Bangladesh, bringing rain and strong winds to Rajshahi and Rangpur. It created havoc in the metro city of Kolkata.
The name Amphan was suggested by Thailand which means 'sky' in Thai.
Meteorological history.
During 13 May 2020, an area of low pressure developed over the Southeastern Bay of Bengal about to the southeast of Visakhapatnam in the Indian state of Andhra Pradesh. ;ref name="STWA 13/05/20" ; ;/ref ; The area of low pressure was located within a favorable environment for further development with good equator-ward outflow, exceptionally warm sea surface temperatures between 32 and 34 °C recorded in the basin, and low vertical wind shear. Over the next couple of days, the system became more marked as it gradually consolidated further, with bands of deep atmospheric convection wrapping into the system's low-level center. ;ref name="TCFA 15/05/20" ; ;/ref ; During 16 May, the India Meteorological Department (IMD) reported that the area of low pressure had developed into a depression and designated it as BOB 01 while it was located about to the south of Paradip in the Indian state of Odisha.
Moving northwards, the depression continually organised and became a cyclonic storm a few hours later, receiving the name "Amphan". Intensification was temporarily impeded as moderate easterly wind shear disrupted the system's cloud pattern. On 17 May, conditions for significant intensification became more conducive as upper-level winds improved. As a result, Amphan underwent rapid intensification into a severe cyclonic storm, with the JTWC assessing an increase in winds from at 12:00 UTC to , the equivalent to a Category 4 hurricane on the Saffir–Simpson scale (SSHWS), just six hours later. Furthermore, the IMD upgraded Amphan to an extremely severe cyclonic storm on their cyclone intensity scale. The broad storm was characterized by a cloud shield extending more than and a sharply-outlined 10 nautical mile-wide eye.
Early on 18 May, microwave imagery depicted two distinct concentric eyewalls, a telltale sign of an eyewall replacement cycle that is typical for very intense cyclones. Through the day, the effects of wind shear and dry air hampered this internal core change, causing the eyewall to erode by late on 18 May. Around 5:30 p.m. IST (12:00 UTC), Amphan made landfall as a Very Severe Cyclonic storm near Bakkhali, West Bengal with winds of .
As it moved further inland, Amphan rapidly weakened. Just six hours after landfall, the JTWC downgraded the storm to a Category 1-equivalent cyclone and issued its final warning on the system, as it became disorganized. On 21 May, Amphan degenerated into a well-marked low pressure area.
Preparations.
Amphan's forecast track placed 38.9 million people in India and Bangladesh at risk of exposure to the storm's winds, according to the US Pacific Disaster Center. The formation of the precursor low-pressure system prompted the IMD to issue a cyclonic alert for India's coastline along the Bay of Bengal, advising fishermen not to sail to susceptible locations in the Bay of Bengal from 15 to 18 May. Fishermen from Sri Lanka were also advised by the national government to return to or remain in the country, and additional maritime traffic from Singapore and other countries were advised to remain clear of Amphan's vicinity. Ships and aircraft of the Indian Coast Guard directed fishing boats to harbour in coordination with the administrations and fisheries departments of Odisha and West Bengal. The Maritime Rescue Coordination Centre in Chennai activated an International Safety Net for the Bay of Bengal. Ports were cleared and their operations suspended along the Bay of Bengal, while ferry service along major routes in Bangladesh was suspended by the Bangladesh Inland Water Transport Corporation. Bangladeshi ports suspended the loading and unloading of goods on board ships. Smaller vessels in the harbour at Chittagong were moved to safety upstream the Karnaphuli River. Ships were ordered out of some ports, such as the port of Paradip, to avoid damage. Public works departments were called upon by the government of Odisha to ensure infrastructure resiliency; crews and backup systems for electricity and telecommunications were deployed to meet these needs, establishing helplines for emergency response. Rail and vehicular traffic in Odisha and West Bengal was halted or rerouted. The "Shramik" train service for migrant workers was halted in both states for up to four days, with service expected to be curtailed in the storm's aftermath. Other migrants travelling to Odisha were asked to wait out the storm. AC Express special trains operating routes between New Delhi and Bhubaneswar were diverted to avoid the cyclone's effects. Netaji Subhas Chandra Bose International Airport in Kolkata was closed until 21 May, with planes evacuating or chocked and the airport terminal roof fortified to minimize damage.
Prime Minister Narendra Modi held a meeting with Minister of Home Affairs Amit Shah, Chief Minister of West Bengal Mamata Banerjee, Chief Minister of Odisha Naveen Patnaik and other officials on 18 May to review preparations and evacuation plans. Chief Minister of West Bengal, Mamata Banerjee announced on the day of hitting of cyclone, that all the areas through which the cyclone will pass are to be disconnected from the power supply until the disaster passed on, except the important places like hospitals, fire station etc. Teams from the Odisha Disaster Rapid Action Force and National Disaster Response Force (NDRF) were pre-positioned across districts in Odisha and West Bengal on 17 May to assist in preparations for Amphan and render aid where necessary, with additional units placed on standby; these units could be readily airlifted to affected areas on board Indian Air Force transport aircraft. The National Disaster Management Authority advised that these crews and other first responders would also need personal protective equipment and N95 masks due to the ongoing pandemic. A diving team from the Indian Navy was sent to Kolkata to aid relief efforts, with ships from the navy placed on standby for relief operations.
The Bangladesh Cyclone Preparedness Programme and National Disaster Response Coordination Group convened on 18 May to outline preparations for Amphan. Several non-governmental agencies coordinated with the Cyclone Preparedness Programme to support Rohingya refugees at camps in Cox's Bazar during Amphan. The Department of Public Health Engineering distributed sanitation supplies and set up 15 water treatment plants. All 32 Rohingya camps in Cox's Bazar were staffed with relief volunteers. Health services in Bangladesh during the storm were reinforced by 1,933 medical teams distributed around Bangladesh. Fifteen thousand volunteers and 284 medical teams were prepared to render aid around Chittagong. According to Inter-Services Public Relations, 145 disaster management teams from the Bangladesh Armed Forces were placed on standby with special equipment. The Bangladesh Army deployed 71 medical teams and arranged 18,400 packets and relief materials in preparation for Amphan's aftermath. Twenty-five ships were dispatched by the Bangladesh Navy to handle emergency, rescue, and relief operations, with aerial support from the Bangladesh Air Force. The Ministry of Agriculture of Bangladesh advised coastal farmers to harvest all mature paddy fields to mitigate the estimated loss of 12 percent of crop yield. Seven thousand domestic animals were also moved to shelter under the direction of the Ministry of Fisheries and Livestock.
An IMD yellow alert was active for 13 of Kerala's 14 districts on 18 May, while an orange alert was issued by the agency for West Bengal, anticipating extensive damage in six districts. The Bangladesh Meteorological Department issued cyclone danger signal #10, their highest warning, at the Port of Mongla and the Port of Payra on 20 May, signifying "great danger" due to Amphan with winds expected to exceed . Signal #10 was also issued for eleven coastal districts, in addition to offshore islands and islands within the Ganges Delta. Flood and landslide warnings were issued by the Disaster Management Centre of Sri Lanka on 19 May. Boats, helicopters, and crews were stationed by the Sri Lanka Air Force and Sri Lanka Navy throughout the island to bolster emergency response. Coastal provinces of Thailand along the Andaman Sea were warned by the Thai Meteorological Department of the threat of heavy rain on 19 May. Storm alerts issued by the Thai Department of Disaster Prevention and Mitigation encompassed 62 provinces, including Bangkok, while warnings for flash floods, high waves, and landslides were issued for 14 provinces in southern Thailand. The National Centre for Hydrology and Meteorology of Bhutan warned of the possibility of flash flooding and landslides in the country. The Bhutanese Department of Disaster Management advised against travelling, particularly in southern Bhutan.
Evacuations.
The government of Odisha directed the magistrates of four districts on 15 May to establish shelter homes for possible evacuees. Odisha Chief Secretary Asit Kumar Tripathy initially identified 403 possible cyclone shelters in areas potentially impacted by Amphan, though 105 served as temporary medical centres for quarantines associated with the concurrent COVID-19 pandemic. Shelters could only be filled to one-third capacity to maintain social distancing guidelines due to the pandemic. Social distancing restrictions in West Bengal reduced evacuation capacity in shelters from 500,000 people to 200,000 people. The Kolkata Municipal Corporation located schools and community centres for possible use as temporary shelters to augment evacuation capacity. At least 1,704 shelters were ultimately established in Odisha and more than 2,000 were used in West Bengal, including schools and public buildings. Pandemic constraints on shelters in Bangladesh prompted deputy commissioners in 19 coastal districts to seize educational institutions and mosques for use as shelters. More than 12,000 shelters were opened across Bangladesh, supplied with food and emergency cash from the Bangladeshi Ministry of Disaster Management and Relief and yielding capacity for 5.19 million evacuees. There were 5,767 more shelters in Bangladesh for Amphan than for Cyclone Bulbul, which struck the country in November 2019, due in part to social distancing restrictions.
Approximately 4.2 million people were evacuated in coastal India and Bangladesh, with roughly 2 million from India and 2.2 million from Bangladesh. Most of the evacuations in India occurred in West Bengal. Over a million people were expected to evacuate from areas near the Bangladesh–India border. Around 4,000 personnel from the SDRF oversaw evacuations in India. Evacuations began on 17 May in Jagatsinghpur, beginning with the elderly and pregnant living in thatched homes. Magistrates were directed to begin evacuating residents from vulnerable homes and low-lying areas in Odisha the following day. The Odisha government took a more targeted evacuation approach for Amphan than in previous storms where more widespread evacuations were utilized. Odisha had shelter capacity for up 1.1 million evacuees, though only