A new system brewing over Bengal and the position of the monsoon trough are likely to make the next week rainy as well, a Met office said.

“The monsoon trough at mean sea level now passes through Ganganagar, Pilani, Agra, Churk, Ranchi, Digha and thence southeastwards to east-central Bay of Bengal,” said a Met bulletin issued on Wednesday afternoon.

“Yesterday’s cyclonic circulation over the Gangetic West Bengal and adjoining Bangladesh now lies over Gangetic West Bengal and adjoining areas of Jharkhand and North Odisha and extends up to 5.8km above mean sea level.... Under its influence, a low-pressure area will likely form over the same area during the next 24 hours.”

For south Bengal, the bulletin predicted “light to moderate rainfall in “most places” on Thursday; in “many places” on Friday and again “most places” from August 10 to 13.

Heavy rainfall (7-11cm) is likely in Purulia, West Burdwan and Birbhum on August 10 and in North and South 24-Parganas on August 11.

In north Bengal, heavy rain is likely in Darjeeling, Jalpaiguri, Kalimpong and Coochbehar and “heavy to very heavy rain (7-20cm)” is likely in Alipurduar on Thursday.

Heavy rainfall is likely in Darjeeling, Kalimpong, Jalpaiguri and Alipurduar districts on Friday.

“The next few days are expected to continue being rainy in Calcutta,” said a Met official.

On Wednesday, the city received a spell of rain in the afternoon.

The monsoon was lean since its arrival in south Bengal on June 21. The monsoon deficit in Calcutta, around 50 per cent at the end of June, had been narrowed to around 30 per cent towards the end of July.

“Steady rain for the past few days has narrowed the deficit to around 20 per cent now,” said the Met official.