Cyclone Sitrang is likely to make landfall between two islands in Bangladesh on Tuesday morning, according to the Met office.
The two islands are Sandwip, along the southeastern coast in the Chittagong district, and Tin Kona, part of the Sunderbans in Bangladesh.
Sandwip is over 500km from Kolkata and Tin Kona Island is close to 200km away. The closer the landfall is to Sandwip, the lesser the expected impact on Kolkata, said a Met official.
On Saturday, the system was a depression over east-central Bay of Bengal, around 1000km from the southernmost tip of Bengal.
As the storm barrels towards Bangladesh, the coastal districts of south Bengal are expected to get widespread rain on Monday and Tuesday.
A Met official said North and South 24-Parganas, the two districts which share the mangrove delta with Bangladesh, are likely to be impacted the most by the storm.
Heavy rain has been predicted for both districts on Monday and Tuesday. East and West Midnapore and Nadia are also likely to get heavy rain on Monday and Tuesday, respectively.
Kolkata, Howrah and Hooghly are likely to get moderate rain on both days.
A Met official said that as of now, the southern fringes of Kolkata, like Joka and Behala, could also end up getting heavy rain, which, in Met parlance, translates to 60mm or more in 24 hours.
On Monday, winds blowing at 45-55kmph, with gusts clocking 65kmph, are likely over North and South 24-Parganas and East Midnapore districts. Calcutta, Howrah, Hooghly and West Midnapore are likely to see gusts clocking 50kmph.
On Tuesday, the wind speed is likely to go up to 80- 90kmph, with gusts clocking 100kmph, in North and South 24-Parganas. The maximum windspeed likely over East Midnapore is 80kmph.
Kolkata, Howrah, Hooghly and West Midnapore are likely to get winds blowing at 50kmph with gusts clocking 60kmph.
“The clouds in the outer band of the system are the first to reach land. The winds start hitting later. That is why more rain is expected on Monday and the intensity of the winds is likely to go up on Tuesday,” said G.K. Das, director, India Meteorological Department, Kolkata.
The maximum impact on Kolkata is likely between Monday evening and Tuesday morning, said Das.
A Met bulletin on Saturday evening said, around 11.30 am, the system was a depression “over east-central and adjoining south-east Bay of Bengal, about 270 km north-northwest of Port Blair, 950 km south-southeast of Sagar Island and 1010 km south of Barisal in Bangladesh”.
“It is very likely to move northwestward and intensify further into a deep depression over east-central and adjoining south-east Bay of Bengal by October 23 morning. Subsequently, it is very likely to recurve gradually north-northeastwards and intensify into a cyclonic storm over central Bay of Bengal by October 24 morning. Thereafter, it would continue to move north-northeastwards and cross Bangladesh coast between Tin Kona Island and Sandwip around October 25 early morning,” said the bulletin.