A cyclonic circulation over the Bay of Bengal would keep large parts of Bengal, especially its coastal and Gangetic regions, wet over the weekend and is likely to spill over into the first half of next week.

The forecast from the Indian Meteorological Department was prompted by the cyclonic circulation that is formed over North East and adjoining East Central Bay of Bengal adjacent to North Andamans Sea close to the Myanmar coast that has now intensified into a low pressure area and is likely to further strengthen into a marked low pressure area in the next 24 hours. The intensity and spread of the rains are likely to pick up once the system begins to move northwestwards towards north Odisha and adjoining West Bengal coasts in the next couple of days brining sporadic and at times well-spread showers across the state till October 3, a special bulletin issued by the Met office stated.

Besides Bengal, the system would also bring rains over the next few days to the adjacent states of Odisha and parts of Jharkhand and Bihar.

While the climatic developments would surely bring the mercury down by a couple of notches and offer relief from the erratic heat at the onset of autumn, the rains may not be good news to the state and its administration which is grappling with the dengue menace for sometime now.

The fresh systemic formation over the bay has ensured additional moisture in air and opened up the likelihood of a delay in monsoon receding from this part of the country. With barely three weeks remaining before Durgs Puja revelry begins in Bengal, that possibility left jitters among Puja organizers and pandal hoppers alike.

Sanjib Banerjee, director of the Alipore met office however said: “The recession of Monsoon doesn’t exactly happen at the end September in this part of the country and it is perfectly normal for the rains to persist till the middle of October. So far, we do not have any indication that the rains would affect the Pujas. But these are early days to make any kind of prediction about that.”

As for the impending rains, the weather office has issued a Yellow warning of heavy rains ranging between seven to 11 cms on Friday at isolated places over Calcutta, Howrah, Hooghly and the coastal districts of East and West Midnapore as well as North and South 24 Parganas.

On Saturday, that alert is raised to the Orange category with heavy to very heavy showers accompanied by thunder and lightning over parts of East and West Midnapore and Jhargram districts where rainfall could range between seven to 20 cms. Calcutta and the south Bengal districts of South 24 Parganas, Bankura, Purulia Howrah, Hooghly and East Burdwan are likely to receive isolated rainfall in the Yellow zone on that day, the met office predicted. On Sunday, similar rainfall in the Yellow alert category could be experienced in isolated regions over Murshidabad, Birbhum, East and West Burdwan districts.

On Monday and Tuesday, the packed skies would be more apparent in the northern parts and upper reaches of the state with districts like Malda, North and South Dinajpur, Darjeeling and Kalimpong remaining within the Yellow alert category and one or two places in Cooch Behar, Jalpaiguri and Alipurduar bracketed inside the more intense Orange category alert.

During the period, the coastal districts of the state are likely to experience gusty winds speeding up to 45 kmph in spells, an IMD Calcutta official stated. Although the intensity of the rains would be in the light to moderate range for most parts of the state, it is likely to be widespread during this time, he added.

Possible impact of the rains, the weathermen predicted, is likely to be felt in the form of landslides in the hills, rise in water levels in rivers and water logging in low lying areas alongside reduction in visibility. Fishermen have been warned to not venture to the seas till Tuesday next week.