The city is likely to get some rains from Wednesday as another depression has formed over west-central Bay of Bengal.
According to a weather bulletin released at 8 p.m. on Tuesday, the depression now lies 550 km east-northeast of Chennai and 350 km south-southeast of Visakhapatnam.
It will intensify into a deep depression and cross south Andhra Pradesh and adjoining north Tamil Nadu coast between Chennai and Ongole on Thursday night.
The rains could prove critical for the city, as the reservoirs feeding the piped water supply have just 30 per cent of the annual requirement.
For a comfortable daily supply through the year, the city needs at least 8,000 million cubic feet of water in the four reservoirs situated in the city’s fringes. Currently, the cumulative storage stands at approximately 3,500 million cubic feet.
Weather systems that bring rain to the catchment areas of the reservoirs will lead to an increased storage. Rains within city limits will also help improve the groundwater situation through the rainwater harvesting structures.
Officials of the meteorological department said there may be isolated heavy rainfall in areas of coastal Andhra Pradesh and north coastal Tamil Nadu.
Chennai too may get rains from Wednesday, an official said. Chennai has a rainfall deficit of 56 per cent for the northeast monsoon so far. It has registered 331.8 mm of rainfall since October 1, the official said.
A few more spells of rain are required to reduce the deficit. For Wednesday, the Met department has forecast rain or thundershowers in Chennai.
