A low pressure system active over Bay of Bengal is unlikely to trigger heavy rain in Kolkata even after gaining steam and entering land.
The city is expected to get enhanced rainfall activity between Tuesday and Thursday, said a Met official. South and North 24-Parganas, Purba Medinipur, Paschim Medinipur and Jhargram districts are likely to get heavy rain.
Weather scientists tracking the system said it took shape on Sunday and was near the south Odisha and north Andhra coastline on Monday. It is tipped to intensify into a depression and enter land on Tuesday. Then, it is expected to move west, through Odisha and Chhattisgarh. The system is likely to weaken as it keeps moving, said a Met official.
The system has gone further south than expected, the official said.
The low-pressure area was near Puri on Monday evening. The monsoon trough extended from Rajasthan to the Bay, meeting the system.
“The southwest sector of any system, be it a cyclone or a low-pressure area, gets maximum rainfall. In the case of the present system, Gopalpur in Odisha and neighbouring areas are on the southwest of its centre,” said G.K. Das, director of IMD, Kolkata.
Gopalpur is over 600km from Kolkata.
The shifting of the monsoon trough is, however, expected to trigger rain in Kolkata over the next couple of days. “The trough will rise as the system enters land. The eastern part of the trough is likely to come closer to south Bengal on Wednesday. Kolkata is expected to be in the convergence (cloud formation) zone,” said Das.
The civic authorities in Kolkata said they were prepared. “We have an adequate number of pumps and the pumping stations are ready. We have placed sufficient portable pumping stations in areas prone to waterlogging,” said an official of the KMC’s drainage department.
But he also cautioned that sustained heavy rain can lead to waterlogging despite the best efforts of the workers and machines.
A Met bulletin on Sunday had predicted “heavy rain” in Kolkata and “very heavy rain” in some districts because of the system. On Monday, the Met office issued a scaled-down bulletin, in which Kolkata did not feature in places expected to get heavy rain.
According to the latest bulletin, heavy rain is likely in South 24-Parganas, Jhargram and Purba and Paschim Medinipurs on Tuesday, Wednesday and Thursday. North 24-Parganas is likely to get heavy rain on Wednesday.
South 24-Parganas, Purba Medinipur, Paschim Medinipur and Jhargram are also likely to get gusty winds on Tuesday and Wednesday, the forecast said.
“Light to moderate rain with thunder” is expected across south Bengal between Tuesday and Thursday.