The state of Tamil Nadu is expected to experience continued wet weather until the end of November, driven by two developing weather systems that are likely to intensify and bring heavy rainfall, particularly to the southern districts. The Regional Meteorological Centre (RMC) in Chennai has issued forecasts and alerts indicating that the Northeast monsoon is entering a more vigorous phase this week, with significant implications for rainfall distribution across the state.
At present, a well-marked low-pressure area is located over Malaysia and the adjoining Strait of Malacca, accompanied by an associated cyclonic circulation. Meteorologists anticipate that this system will consolidate into a depression over the South Andaman Sea by Tuesday and subsequently intensify into a cyclonic storm over the South Bay of Bengal by Thursday. Should it reach cyclonic storm status, this system will be named ‘Senyaar’, a name contributed by the United Arab Emirates. Alongside this, another upper air circulation over the Comorin area and neighboring regions is expected to develop into a low-pressure area by Tuesday, further enhancing rainfall activity in the state.
These weather systems are currently influencing precipitation patterns over Tamil Nadu, particularly in the southern districts. Recent heavy rains have effectively erased the seasonal rainfall deficit that the state had been experiencing. Since October 1, Tamil Nadu has received approximately 34 cm of rainfall, which is about 5% more than the normal 32.3 cm for this period. However, certain districts, including Chennai, Chengalpattu, and Dindigul, continue to experience rainfall shortfalls and have not yet reached their seasonal averages.
During the 24-hour period ending at 8:30 a.m. on Monday, several locations reported heavy rainfall, with Oothu in Tirunelveli district recording the highest amount at 23 cm. The RMC has forecast that heavy rainfall will persist over at least four districts, including Tirunelveli and Ramanathapuram, on Tuesday. As the weather systems develop further, intense downpours are expected to spread to additional areas in the southern and delta districts. To prepare the public and authorities for these conditions, the meteorological department has issued orange and yellow weather alerts for various districts between November 28 and 30.
Looking ahead, northern districts such as Chennai and Chengalpattu may face very heavy rainfall on November 29, with Tiruvallur district placed under an orange alert for November 30. These alerts are part of the effort to mitigate risks posed by the intensified monsoon activity and to help communities prepare for potential flooding and disruptions.
B. Amudha, the Additional In-charge and Head of the Regional Meteorological Centre, explained that the interaction between three key weather systems—including a cyclonic circulation over the southeast Arabian Sea—will significantly affect the weather dynamics and rainfall potential in Tamil Nadu. Such interactions are common during the Northeast monsoon season, particularly in the equatorial trough zone, where one weather system can feed moisture into another, thereby amplifying rainfall intensity.
Ms. Amudha highlighted that the team at RMC is closely monitoring the possibility that the system near the Strait of Malacca might merge with the system near the Comorin area, potentially moving as a single, more powerful weather system. She noted that more clarity on the behavior and impact of these weather disturbances would emerge within the next two to three days.
Regarding the recent heavy rains in the southern districts, Ms. Amudha pointed out that localized atmospheric activity along the ghat areas can sometimes intensify rainfall in specific places. This local enhancement is a contributing factor to the torrential downpours observed in some regions. She expressed optimism that November’s overall rainfall would be normal, if not above average, due to the increased precipitation associated with these evolving weather systems, which are expected to boost seasonal rainfall totals and eliminate any remaining deficits.
In summary, Tamil Nadu is currently under the influence of multiple weather systems that are intensifying the Northeast monsoon, bringing substantial rainfall, especially to the southern parts of the state. This shift is expected to continue through the end of the month, with forecasts indicating heavy to very heavy rains spreading northwards towards Chennai and surrounding districts in the coming days. The RMC is actively tracking these developments to provide timely updates and warnings, helping residents and authorities prepare for the potentially challenging weather conditions ahead.