CHENNAI: The northeast monsoon rainfall over Tamil Nadu is expected to be normal overall, VR Durai, director of the Chennai Regional Meteorological Centre (RMC), said on Thursday, even as the weather department has forecast heavy rain with thunderstorms and lightning in Chennai and 25 other districts on Saturday.

Widespread rain was witnessed in Chennai and its suburbs on Thursday, with the city recording light rain and while suburbs saw moderate to heavy rainfall.

Addressing the media, Durai said northern districts are likely to receive below-normal rainfall, southern districts above-normal rainfall, and coastal districts normal rainfall.

The southwest monsoon ended with a 20% deficit this year, with Tamil Nadu, Andhra Pradesh, Kerala and neighbouring regions experiencing below-normal rain and intense heat. Southern districts received normal rainfall, while interior districts recorded below-normal rainfall.

Durai said the southwest monsoon withdrew completely from all parts of the country on Thursday. Northeasterly winds have begun blowing over the southern peninsula, and the northeast monsoon has commenced over Tamil Nadu, Puducherry and Karaikal, coastal Andhra Pradesh, Rayalaseema, south interior Karnataka, Kerala and Mahe.

On the impact of El Niño, he said Tamil Nadu has historically received higher rainfall in such years, but the formation of low-pressure areas is likely to be low. El Niño conditions are expected to persist until January-February next year.

Moderate rain with thunderstorms and lightning is likely in some areas in Chennai on Friday.

As per the forecast for Friday, heavy to very heavy rain at isolated places, with thunderstorms, lightning and gusty winds of 40-50 kmph, is likely over the Nilgiris, Coimbatore, Theni, Dindigul, Tenkasi and Madurai.

Heavy rain at isolated places is likely over Erode, Tiruppur, Virudhunagar, Kanniyakumari, Cuddalore, Karur, Puducherry, Ariyalur, Pudukottai, Villupuram, Ramanathapuram, Sivaganga, Tiruchirappalli, Namakkal, Dharmapuri, Krishnagiri, Salem, Tiruvannamalai, Kallakurichi, Ranipet, Tiruvallur, Mayiladuthurai, Nagapattinam, Tiruvarur, Thanjavur and Karaikal. The rest of Tamil Nadu and Puducherry may receive moderate rain at many places.

On Saturday, heavy rain with thunderstorms, lightning and gusty winds of 40-50 kmph are likely at isolated places over the Nilgiris, Coimbatore, Theni, Dindigul, Madurai, Tiruppur, Chennai, Tiruvallur and Chengalpattu.