IMD issues red alert for Tiruvallur, Kancheepuram and Ranipet districts on November 11

CHENNAI 

The Regional Meteorological Centre (RMC), Chennai has issued a red alert for Tiruvallur, Kancheepuram and Ranipet districts tomorrow, where red stands for the possibility of very heavy to extremely heavy rainfall (above 20cm). Following this, holiday has been issued for schools and colleges in Chennai, Tiruvallur, Kancheepuram, Chengalpattu, Ranipet and Vellore districts on Friday.  

Orange alert, meaning heavy to very heavy rainfall (12cm to 20 cm), has been issued for districts including Chennai, Chengalpattu, Villupuram, Vellore, Tirupattur, Tiruvannamalai, Kallakurichi, Cuddalore, Ariyalur, Perambalur, Tiruchi, Thanjavur, Tiruvarur, Mayiladuthurai and Nagapattinam districts, Puducherry and Karaikal.  

According to Additional Director General (Meteorology) S. Balachandran, the low pressure area (LPA) over Southwest Bay of Bengal off Sri Lanka coast was likely to become more marked by Friday. It is very likely to move northwestwards towards Tamil Nadu and ­Puducherry coasts till Saturday morning. It is likely to move west­northwestwards and move across Tamil Nadu, Puducherry and Kerala during Saturday and Sunday.    

On Friday and Saturday, light to moderate rain at most places with isolated thunderstorm and lightning has been forecast over Tamil Nadu, Puducherry and Karaikal. Heavy rain is likely to occur at isolated places in the Delta and western districts on both these days. On Saturday, red alert has been issued for Nilgiris, Dindigul and Theni districts.  

On Sunday, the department has forecast light to moderate rain at most places with isolated thunderstorm and lightning likely to occur over Tamil Nadu, Puducherry and Karaikal. Heavy to very heavy rain is likely to occur at isolated places over Nilgiris, Theni, Dindigul, Madurai, Tirupattur, Vellore, Ranipet, Tiruvallur and Kancheepuram districts. Heavy rain is likely to occur at isolated places over Coimbatore, Tiruppur, Erode, Krishnagiri, Chennai, Chengalpattu, Tiruvannamalai, Villupuram, Cuddalore, Mayiladuthurai, Nagapattinam, Tiruvarur, Sivaganga, Ramanathapuram, Virudhunagar, Thoothukudi, Tenkasi, Tirunelveli, Kanyakumari districts of Tamil Nadu, Karaikal and Puducherry.  

P. Senthamarai Kannan, Director, Area Cyclone Warning Centre explained that all cyclonic systems were LPAs and they were classified based on wind speed. In this LPA, the destruction due to wind will not be there, but flooding would be there based on quantum of rainfall. Since there is no centre or eye like a cyclone, there will not be any landfall but the clouds would cross and go towards the west and thereon to the Arabian Sea, he added.  

Weather blogger Pradeep John explained that an LPA was spread over hundreds of kilometres bringing widespread rainfall. “The forecast is light to moderate rainfall and almost the entire State is getting rain spread over three days. Based on how the clouds move, we will have breaks between rain spells. This evening’s showers in the city were intense and within a short time,” he said.