“Low pressure has formed over the central Bay of Bengal. It is an east­-west trough roughly along 14°N across peninsular India and cyclonic circulation over the central Bay of Bengal and the neighbourhood between 1.5 km and 3.1 km above mean sea level tilting southwards with height,” said S Balachander, director. Regional Meteorological Centre, Chennai.

North Chennai received a lot of rain, with Nungambakkam recording 26.6 mm rainfall and Meenambakkam only 0.3 mm. The maximum temperatures recorded at Nungambakkam and Meenambakkam were 28.4 and 29 degrees Celcius respectively, and minimum at 25 and 25.6 degrees.

“The low pressure is predicted to move to north but it would trigger intense thunderstorms in north TN between October 22 and 24, while our monsoon easterlies are seen entering the Bay of Bengal on October 27,” said Pradeep John, who runs the page Tamil Nadu Weatherman.

Districts like Salem, Dharmapuri, Perambalur, Tiruchy, Ariyalur, Thanjavur, Tiruvarur, Tiruvannamali, Villupuram, Kallakurichi, Vellore, Ranipet and Pudukottai are expected to get heavy rainfall over the next 48 hours. Chennai will have moderate rains and thunderstorms, with cloudy skies and temperatures between 26 and 30 degrees Celcius.

Heavy rain wreaked havoc in Salem and Coimbatore districts as several low lying areas and roads were inundated, causing traffic hurdles.

Residents of a few neighbourhoods in Salem spent a sleepless night after water entered their houses following heavy downpour since Monday night. Due to block in drainage canals leading to Kumaragiri lake, water flowed into some low lying areas such as Narayana Nagar, Erumapalayam and Kitchipalayam, resulting in flooding.

Residents claimed that despite them raising the flooding issue with the Corporation multiple times, the officials have failed to take any efforts to remove blocks in waterways and ensure smooth flow of water. Similarly, some low lying houses in Pachapatty were flooded.

In Coimbatore, several roads came under water, causing traffic hurdles after it rained for more than an hour on Tuesday afternoon.

There was water stagnation under Avinashi Road flyover, Kikani rail overbridge, Kattur railway bridge and north Coimbatore flyover. At Lanka Corner, the sewage mixed with rainwater stagnated for about two feet forcing vehicles to wade through in these areas.