A system over Bangladesh triggered consistent rain in Calcutta since Saturday night, leaving several roads waterlogged.

The Met office has predicted more rain on Monday as well, unless the system moves quicker than expected and reaches Jharkhand by Monday morning.

Between 8.30pm on Saturday and 8.30pm on Sunday, the Met office recorded over 57mm of rain in Alipore.

The showers were the strongest in the city between 9am and 1pm. Figures from the pumping stations of the Kolkata Municipal Corporation show that Maniktala got 67mm of rain in the four hours. During the same period, Palmer Bazar received 62.5mm of rain, Ultadanga 60mm, Ballygunge 52mm and Behala 43mm.

Multiple stretches of Central Avenue and Mukataram Babu Street were waterlogged on Sunday afternoon. Had it been a working day, the impact of the rain could have been much more on the traffic.

Parks and museums were much less crowded than they are on a Sunday.

Only a handful of people with umbrellas were seen at the ticket counters of the Victoria Memorial and the Alipore zoo.

The low-pressure area was over south Bangladesh and its neighbouring areas on Sunday morning, a Met bulletin said.

“It is likely to move slowly north-northwestwards and become a well-marked low pressure area over Bangladesh and adjoining Gangetic West Bengal by August 19. Thereafter, it is likely to move westnorthwestwards across Gangetic West Bengal, Jharkhand and adjoining Bihar and Uttar Pradesh and adjoining Madhya Pradesh during the subsequent 3-4 days,” the bulletin said.

“The monsoon trough at mean sea level now passes through Bikaner, Sikar, Orai, Sidhi, Ranchi and thence to the centre of low-pressure area over south Bangladesh and neighbourhood.”

The trough passes over south Bengal, not very far from Calcutta, said a Met official.

The system over Bangladesh is likely to move via Bengal on its way towards the heartland states.

Districts like North 24-Parganas, Murshidabad, Bankura, Birbhum, Nadia, East and West Burdwan and Purulia are likely to get drenched as the system moves to Jharkhand.

There is a forecast for heavy rain for the entire south Bengal, including Calcutta, for Monday.

“In Calcutta, the intensity of the rain is likely to dip as the system moves further away from the city,” said a Met official.