How El Niño Shaped the Path and Intensity of Cyclone Arnab

Context

Cyclone Arnab intensified over the Bay of Bengal in October 2026, prompting meteorologists to examine how El Niño conditions influenced its development, movement and intensity.

Key Highlights

• Cyclone formation and intensification: Cyclone Arnab developed over the southeastern Bay of Bengal around October 23 and intensified into a cyclonic storm by October 26, with wind speeds reaching approximately 125 – 135 kmph.
• Storm intensity: It strengthened into a very severe cyclonic storm, with wind speeds initially reaching around 125 – 135 kmph and subsequently increasing to approximately 140 kmph, according to the report.
• Landfall and impacts: The cyclone made landfall near the Andhra Pradesh coast between Bapatla and Visakhapatnam, bringing heavy rainfall and causing flooding in coastal districts.
• El Niño and atmospheric circulation: El Niño involves abnormal warming of surface waters in the central and eastern equatorial Pacific Ocean. It can alter atmospheric circulation, monsoon rainfall patterns and conditions favourable for cyclone development.
• Influence on cyclone tracks: During El Niño years, tropical cyclones in the North Indian Ocean may form farther south and move towards Andhra Pradesh and Tamil Nadu instead of following the more typical northward or northeastward tracks.
• Factors behind rapid intensification: Warm ocean temperatures, high ocean heat content, low vertical wind shear and favourable atmospheric conditions can contribute to the rapid intensification of tropical cyclones.

Key Concepts

• El Niño: Periodic warming of the central and eastern equatorial Pacific Ocean, forming part of the El Niño Southern Oscillation (ENSO) phenomenon.
• Vertical Wind Shear: The difference in wind speed or direction at different atmospheric heights. Strong vertical wind shear generally inhibits tropical cyclone development.
• Ocean Heat Content: The heat stored beneath the ocean surface, which can sustain cyclone intensity even when surface waters cool.
• Rapid Intensification: A substantial increase in a tropical cyclone’s maximum sustained wind speed over a short period.

How Are Cyclones Named?

• Origin of naming: Tropical cyclones in the Bay of Bengal and Arabian Sea began being named in September 2004, following a meeting of an intergovernmental panel in 2000.
• Contributing countries: Initially, eight countries provided names: Bangladesh, India, the Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand. In 2018, five additional countries joined: Iran, Qatar, Saudi Arabia, the UAE and Yemen.
• Naming procedure: Participating countries suggest a list of names, which are finalised by the panel. The names must follow prescribed guidelines, including being short, easy to pronounce and inoffensive.
• Official assignment: The Regional Specialised Meteorological Centre at New Delhi assigns a cyclone’s name once the system reaches the threshold of 62 kmph to be declared a cyclone.
• Sequential use of names: The 13 member countries are listed alphabetically, and their suggested names are used sequentially. Once all 13 names in a column have been used, the list moves to the next column, with countries again arranged alphabetically. A name is not repeated once used.
• Cyclone Arnab: The name Arnab, pronounced Omab according to the image, was contributed by Bangladesh. The next name in the sequence is Murasu, proposed by India. Murasu is a Tamil word for drum.