The trough of low pressure over the Bay of Bengal will develop into a low pressure area over southeast Bay of Bengal by Saturday.

This relentless spell of rain is expected to continue in the city till Tuesday.

The overnight rainstorm in Chennai swamped several areas in the city and suburbs, flooding houses in low-lying areas and paralysing daily life on Friday. At 21 cm, Puzhal recorded the highest volume of rainfall following overnight rain. The weather stations in Chennai and Meenambakkam recorded 15 cm and 12 cm respectively. However, on Friday, the city received only 1 cm of rain.

Residents of several areas, including Ambattur, Avadi, Thirumullaivoyal and Mudichur are confined to their homes, which have been invaded by knee-deep water. Residents in Avadi on the Chennai-Tiruvallur High Road were affected as the bund of the Kavarapalayam lake was breached.

“The bund of the lake was washed away following heavy rain. Water that flowed from the lake flooded houses,” said S. Vedavalli of Avadi.

As the lake is located near CTH Road, traffic on the arterial road was affected. A team from Avadi municipality finally attended to the breach, four hours after a complaint was made.

City reservoirs, which received between 8 cm and 21 cm of rain, are rapidly getting filled up due to copious inflows from catchment areas. The water body in Chembarambakkam is already one-thirds full. On Friday, the storage of four reservoirs was 3,236 million cubic feet, which is 30 per cent of their total capacity.

Rumours scotched

While there were rumours of the Chembarambakkam lake already brimming, officials of the Water Resources Department said though the lake was receiving heavy inflows, it would take at least 10 more days for it to fill up.

Officials of the meteorological department said Chennai might continue to receive moderate to heavy rainfall till Tuesday. The trough of low pressure over the Bay of Bengal will develop into a low pressure area over southeast Bay of Bengal by Saturday.

Officials of the meteorological department also attribute this to wind surge, a phenomenon in which strong easterlies blowing close to the coast bring moisture to the land region and induce more rainfall.

Y.E.A. Raj, former deputy director general of meteorology, said the northeast monsoon rainfall did not need any weather systems to bring rain. “It is normal for Chennai to get over 15 cm of rain in a single day during the northeast monsoon. In 2009, Chennai received over 40 cm of rain in November. ,” he added.

(With inputs from D. Madhavan)