Second Cyclonic Storm of Season Forms Over Bay of Bengal
The India Meteorological Department has issued significant weather warnings as the season's second cyclonic storm, named Senyar, develops over the Bay of Bengal. The cyclone, whose name means 'lion' and was contributed by the UAE, is expected to bring substantial rainfall to several districts of Tamil Nadu between November 27 and 30.
Rainfall Alerts and District-wise Forecast
IMD has declared an orange alert for very heavy rainfall measuring 12-20 centimeters within 24 hours for three delta districts on November 28. The alert expands to cover seven districts including Chennai on November 29, with Tiruvallur specifically highlighted for November 30.
Additionally, a yellow alert predicting 6-12 centimeters of rainfall has been issued for several southern districts starting November 25, extending to parts of southern and delta regions from November 26 to 28.
On November 28, Thanjavur, Tiruvarur, Nagapattinam, and Karaikal are expected to experience heavy to very heavy rainfall, while Tuticorin, Ramanathapuram, Pudukottai, Cuddalore, and Mayiladuthurai may receive heavy rain.
The rainfall pattern shifts northward on November 29, affecting Mayiladuthurai, Cuddalore, Villupuram, Chengelpet, Chennai, Kancheepuram, Tiruvallur, and Puducherry with heavy to very heavy rainfall. Several other districts including Nagapattinam, Thanjavur, and Tiruvarur will continue experiencing heavy precipitation.
Cyclone Development and Meteorological Factors
As of Monday, weather systems showed a well-marked low-pressure area with cyclonic circulation positioned over Malaysia and the Strait of Malacca. This system is forecast to intensify into a depression over the south Andaman Sea by Tuesday, eventually developing into a full cyclone over the south Bay of Bengal within the next 48 hours.
B Amudha, deputy director general of IMD, explained that three atmospheric circulations may influence rainfall patterns. One circulation over the Kanyakumari region could trigger a low-pressure area extending to adjoining southwest Bay and Sri Lanka by Tuesday, while another develops over the southeast Arabian Sea.
"All three circulations may merge due to upper-air changes," Amudha stated. "We will have clearer details in the coming days regarding their combined impact."
Weather models currently suggest the cyclone may approach the Chennai coast on November 29 and 30, though forecasts vary regarding potential landfall. Some models indicate the system might cross the Andhra Pradesh coast, while others predict a northward movement into the Bay of Bengal before weakening.
Recent Rainfall Patterns and Deficits
The state has already experienced significant rainfall in recent days, with at least 22 weather stations recording between 10-20 centimeters within 24 hours. Oothu in Tirunelveli recorded the highest at 23 centimeters, followed by Nalumukku at 22 centimeters, and Sethiathope in Cuddalore and Kakkachi in Tirunelveli both measuring 21 centimeters.
Since October 1, Tirunelveli has recorded an impressive 85 centimeters of rainfall, representing 138% above normal levels. IMD classification places Tenkasi and Tirunelveli in the "large excess" category with increases exceeding 60%, while five districts show excess rainfall between 20-49%.
However, seven districts including Chennai and Chengelpet remain in deficit, with rainfall 20-59% below normal. Specifically, Chennai has recorded 43 centimeters (25% below normal), Kancheepuram 36 centimeters (13% below normal), Tiruvallur 48 centimeters (8% above normal), and Chengelpet 28 centimeters (43% below normal).
Overall, Tamil Nadu has recorded 34 centimeters of rainfall since October 1, representing a 5% increase above normal levels. The developing cyclone system may help address rainfall deficits in northern districts while potentially causing flooding concerns in already saturated southern regions.
