Amphan Cyclone
Super Cyclonic Storm Amphan (/ˈɑːmpʌn/) is currently a very powerful tropical cyclone over the Bay of Bengal threatening Odisha and West Bengal in India as well as Bangladesh. It is the first tropical cyclone of the 2020 North Indian Ocean cyclone season. Amphan is the first super cyclonic storm in the Bay of Bengal since the 1999 Odisha cyclone.[1][2]
The first tropical cyclone of the 2020 North Indian Ocean cyclone season, Amphan's origins can be tracked back to a low-pressure area situated over the Bay of Bengal on April 29.
During May 13, an area of low pressure developed over the southeastern Bay of Bengal about 1020 km (635 mi) to the southeast of Visakhapatnam in the Indian state of Andhra Pradesh.[3][4] The area of low pressure was located within a favourable environment for further development with good equatorward outflow, warm sea surface temperatures and low vertical windshear.[4] 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 circulation center.[5][6] During May 16, 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 1,100 km (685 mi) to the south of Paradip in the Indian state of Odisha.[7]
Moving northwards, the depression continually organised and became a cyclonic storm a few hours later, receiving the name Amphan. The system was unable to strengthen further as moderate wind shear situated to the east was constantly offsetting the eastern side of the system's convection, making it unsymmetrical.[8] During this time, Amphan torrential rainfall to both Sri Lanka and Southern India, and landslide warnings, as well as flood warnings, were initiated.[9] On May 17, conditions for significant intensification became more likely as the southern shear previously restricting any sort of intensification began to clear, and the shear situated to the north moved further inland. Subsequently, Amphan became a severe cyclonic storm, and then began to undergo explosive intensification, according to the JTWC, with 1-minute sustained winds increasing from 75 knots (140 km/h; 85 mph) at 18:00 UTC to 115 knots (215 km/h; 130 mph) – equivalent to a Category 4 hurricane on the Saffir-Simpson scale – in only six hours. Furthermore, the IMD upgraded Amphan to an extremely severe tropical cyclone on the IMD cyclone intensity scale.[10] At this point, Amphan was an expansive system, with cloudtops extending wider than 600 nautical miles (690 mi; 1,111 km) with super-dense, deep and symmetrical central convection. It also maintained a sharply-outlined 10 nautical mile-wide eye.
At about 00:00 UTC on May 18, microwave imagery depicted that an eyewall replacement cycle was taking place with the presence of two distinct concentric eyewalls, typical for very intense cyclones.
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