A deep depression over the Bay of Bengal strengthened into cyclonic storm Arnab on Monday, setting in motion a weather system that is expected to gather further strength before striking the Andhra Pradesh coast later this week.
The India Meteorological Department said the system, which had developed over the east-central and adjoining southeast Bay of Bengal, intensified into a cyclonic storm during the morning hours after moving nearly westwards at a speed of 15 kilometres per hour over the previous six hours.
According to the weather department's latest bulletin, the storm lay centred around 590 kilometres northwest of Sri Vijaya Puram in the Andaman Islands, 650 kilometres east-southeast of Visakhapatnam in Andhra Pradesh, 730 kilometres east-southeast of Kakinada, 830 kilometres east of Machilipatnam and 910 kilometres east of Bapatla. The position placed the system well out at sea, but its projected track leaves little doubt about the coastline in its path.
Forecasters expect Arnab to move towards the Andhra Pradesh coast and to strengthen into a very severe cyclonic storm before landfall. The system is likely to cross the coast between Bapatla and Visakhapatnam as a very severe cyclonic storm, with maximum wind speeds of 115 to 125 kilometres per hour.
The crossing is expected by the forenoon of October 28, although officials have stressed that the exact path and intensity remain subject to subsequent weather bulletins and could still shift.
The name Arnab was proposed by Bangladesh under the regional naming arrangement for tropical cyclones over the northern Indian Ocean, under which countries around the basin take turns naming storms. It is pronounced Ornab, according to the weather department. A system earns its name once it reaches cyclonic storm intensity, the stage Arnab crossed on Monday after spending Sunday as a deep depression.
In Tamil Nadu, meanwhile, rain continued to lash several parts of the state as the northeast monsoon maintained an active pace. The weather department said more showers are likely in the state till October 27, and it has placed 16 districts on rain alert. Heavy to very heavy rainfall, accompanied by thunderstorms, lightning and strong winds, has been forecast at isolated places in Pudukkottai, Sivaganga and Ramanathapuram districts.
Heavy rain is also likely in Kanyakumari, Tirunelveli, Thoothukudi, Tenkasi, Virudhunagar, Madurai, Theni, Dindigul, Karur and Tiruchirappalli districts. In the Cauvery delta region, Thanjavur, Tiruvarur and Nagapattinam could experience heavy showers at one or two locations, with thunderstorms and gusty winds accompanying the rainfall.
Winds in the affected districts could reach speeds of 40 to 50 kilometres per hour, and the district forecasts point to spells of intense weather rather than uniformly heavy rainfall across every location.
The contrast between the two states captures the different faces of the same system. Tamil Nadu is already feeling the outer influence of the storm in the form of rain and gusty winds, while Andhra Pradesh faces the prospect of a direct landfall at very severe cyclonic storm strength later in the week.
Odisha, too, has begun preparing for the system's approach, stepping up its readiness and mobilising personnel and equipment, while Chief Minister Mohan Charan Majhi deputed eight ministers to vulnerable districts to oversee preparations on the ground.
Andhra Pradesh Chief Minister N Chandrababu Naidu on Sunday directed officials to maintain round-the-clock vigilance and ensure comprehensive preparedness to minimise the impact of Cyclone Arnab and prevent loss of life. The direction came as the system was still a deep depression, underlining how seriously the state administration is treating a storm that is forecast to arrive at very severe strength.
The timing of the storm matters. Late October falls squarely within the northeast monsoon season for Tamil Nadu and the post-monsoon cyclone season for the Bay of Bengal, a period when systems forming over warm sea waters can intensify rapidly as they move towards the Indian coast.
The northeast monsoon, which brings the bulk of Tamil Nadu's annual rainfall, is already active, and the additional moisture and circulation associated with Arnab are adding to the rainfall over the southern peninsula.
For residents, the immediate advice from the authorities is straightforward: remain alert and follow official weather updates as the system intensifies. District administrations in the affected areas are monitoring the situation and its potential impact on vulnerable areas, including low-lying localities and the Cauvery delta, where heavy showers at isolated places can quickly lead to waterlogging.
Motorists in cities such as Coimbatore were already wading through rainwater on Monday morning, a small preview of the disruption that spells of intense rain can bring even before the storm itself arrives.
What happens next depends on how Arnab behaves over the next 48 hours. If it follows the forecast track, it will continue moving towards the Andhra coast, drawing energy from the sea and strengthening into a very severe cyclonic storm before crossing between Bapatla and Visakhapatnam.
If it shifts track or weakens, the rainfall distribution and wind impact could change considerably, which is why the weather department issues fresh bulletins at regular intervals and why officials keep repeating that residents should rely on official updates rather than speculation.
The storm also serves as a reminder of how much of India's eastern coastline lives with cyclone risk every autumn. Andhra Pradesh and Odisha have both invested heavily in early warning systems, cyclone shelters and evacuation planning after past disasters, and the mobilisation seen on Monday, from ministerial deployments in Odisha to round-the-clock vigilance orders in Andhra Pradesh, reflects that institutional memory.
The test of those systems will come as Arnab approaches the coast, when evacuation decisions, power and communication safeguards, and relief readiness all have to work in concert.
For now, the picture is one of a strengthening storm at sea, rain already falling across Tamil Nadu, and three states on alert. The next bulletins will determine whether Arnab stays on its projected course towards the Andhra coast, and at what strength it arrives.
Until then, the forecast stands: a very severe cyclonic storm crossing between Bapatla and Visakhapatnam by the forenoon of October 28, with heavy rain, thunderstorms and gusty winds across Tamil Nadu in the meantime.
(Reporting based on The Hindu and IANS.)