Cyclone Arnab and El Niño: Why the Storm Intensified Rapidly

Cyclone Arnab and El Niño Latest News

• Cyclone Arnab, the first cyclone of 2026 in the North Indian Ocean basin, made landfall on India’s east coast, crossing the Andhra Pradesh and Yanam (Puducherry) coasts. 
• The “very severe” cyclonic storm has since weakened into a “severe” cyclonic storm. It uprooted trees and power poles, triggered widespread power outages, and forced the evacuation of over 1,80,000 people across Andhra Pradesh and Odisha. 
• This raises a key question: what role did El Niño — the abnormal warming of Pacific Ocean surface waters — play in intensifying Arnab?

How Cyclone Arnab Formed and Intensified

• Began as a low-pressure system in the southeast Bay of Bengal on October 23.
• Intensified into Cyclone Arnab by October 26.
• Rapidly escalated into a “severe” and then a “very severe” cyclone — with wind speeds of 125-135 kmph.
• Faster-than-forecast movement: The IMD advanced its landfall prediction from forenoon to early hours of Oct 28.
• Landfall began around 1 am Oct 28, crossing between Bapatla and Visakhapatnam with wind speeds of 125-135 kmph, gusting to 140 kmph — cyclones cause maximum damage at the point of landfall, when the storm’s “eye” crosses from sea to land.

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An Unusual Pattern: Sustained Intensity After Landfall

• Normally, cyclones lose strength upon hitting land due to friction and obstacles.
• Arnab defied this pattern — it maintained intensity for at least six hours after landfall before weakening to a “severe” storm.
• As per IMD, Arnab remained stationary near Narsapur (Andhra Pradesh) and Yanam (Puducherry) since 4 am, slowing the landfall process (normally completed within ~6 hours, depending on cyclone speed/size).
• Heavy rainfall recorded: Visakhapatnam (217mm), Kalingapatam (147mm), Tuni (123mm), Kakinada (118mm), Machilipatnam (115mm), Gopalpur (94mm).

The El Niño Connection

• 2026’s El Niño is forecast to be among the strongest since records began; the World Meteorological Organization (WMO) has warned of its potential impact on Asian cyclones.
• Normal Pattern: Odisha and West Bengal coasts are most prone to Bay of Bengal cyclones.
• During El Niño Years: Cyclones instead tend to affect Andhra Pradesh and Tamil Nadu — linked to where cyclones form and the paths they take.
• Mechanism: El Niño causes abnormal warming in the equatorial and central Pacific, altering rainfall patterns, temperatures, and global wind patterns — including unusual warming in the North Indian Ocean.
• As the southwest monsoon weakens, the monsoon trough (a shifting low-pressure band) moves southwards; El Niño further alters wind patterns and air pressure near the equator.
• Key Effect: During El Niño years, tropical cyclones form closer to the equator, making them more likely to move toward Andhra Pradesh and Tamil Nadu rather than Odisha/West Bengal.
• Historical Precedent: 2014 — another El Niño year — saw Cyclone Hudhud strike the Andhra Pradesh coast.
• Net Effect: Cyclones forming under these conditions tend to intensify rapidly and move faster, as seen with Arnab.

The Science of Cyclone Fuel

• From July to September 2026, sea surface temperatures in the Niño 3.4 region (used to measure El Niño intensity) were 2 to 2.8°C above normal — indicating significantly warmer oceans.
• Cyclone-Favourable Conditions: Ocean temperatures of 26°C or above, at depths of 50-100 metres.
• Tropical cyclones are fuelled by ocean heat — warmer oceans directly contribute to rapid intensification.
• Arnab reached peak “very severe” intensity within a single day — though cyclone intensification is a highly complex process, influenced by multiple factors: boundary layers, wind shear, convection, upper ocean circulation, and air-sea interaction.

Arnab’s Continuing Path and Impact

• Heavy rainfall (64-115mm/24hrs) will continue to batter northern Andhra Pradesh and south Odisha coastal districts through Oct 29.
• Alert status: Odisha and Andhra Pradesh on ‘red’ alert; Chhattisgarh on ‘orange’ alert.
• As Arnab recurves northward, its weakening remnants are expected to bring very heavy rainfall (115-204mm/24hrs) over Telangana, Chhattisgarh, Jharkhand, Bihar, Gangetic West Bengal, eastern Madhya Pradesh, and eastern Uttar Pradesh over the next two days.

Conclusion

• Cyclone Arnab exemplifies how large-scale climate phenomena like El Niño can reshape not just where cyclones strike, but how intensely and how quickly they do so. 
• By warming the North Indian Ocean and shifting cyclone formation closer to the equator, this year’s unusually strong El Niño redirected Arnab toward Andhra Pradesh rather than the traditionally more vulnerable Odisha-West Bengal coast, while also fuelling its rapid intensification and unusually sustained strength post-landfall. 
• As El Niño events are projected to grow more frequent and intense amid climate change, India’s disaster preparedness strategy will need to account for this shifting cyclone geography — treating states like Andhra Pradesh and Tamil Nadu as increasingly high-risk zones during El Niño years, rather than relying solely on historical vulnerability patterns.

Source: IE | BT