The impact of the deep depression over the Bay of Bengal that is set to intensify into a cyclone is likely to be limited to overcast conditions and “light to moderate” rainfall in the city, the Met office said.
The system, expected to turn into a cyclone between Thursday evening and midnight, is likely to make landfall in Bangladesh early on Saturday.
Once the system becomes cyclone, it will be called Midhili, a name given by the Maldives.
“Kolkata is likely to get light to moderate rain, with thunder, on Friday. Rain is not ruled out on Saturday as well. The rain is likely to be accompanied by rumblings of thunder,” said G.K. Das, director of the regional Met office in Alipore.
North-24 Parganas, South-24 Parganas, Howrah, Hooghly, West Midnapore, East Midnapore and Nadia are also likely to get rain on Friday and Saturday. Heavy rain is not ruled out in East Midnapore, Howrah and North and South-24 Parganas.
Kolkata is likely to be spared heavy rain because of two reasons, said Das. One, the possible landfall zone of the storm, between Mongla and Khepupara in Bangladesh, is around 350km from Kolkata, too far for any direct impact on the city.
The other reason is the winds entering Kolkata are northeasterly winds. They are coming from the system via northeastern India.
“Southeasterly winds, which come directly from the Bay, have more moisture than those that come via northeastern India,” said Das.
“The system is tipped to pass by the right side of Kolkata. In a cyclone, the winds flow anticlockwise. Had the system been to the left of Kolkata, the winds would have entered the city directly from the Bay,” he said.
The city was consistently cloudy on Friday but there was hardly any rain.
Around 5pm, the semi-final match at the Eden Gardens was delayed by rain but only for a brief while.
Das linked this to the same reason — the dominance of northeasterly winds.
As the storm comes closer to the Bengal-Odisha coast, the winds will become more potent. They are then expected to trigger some rain in the city.
The overcast conditions have had an impact on the Celsius.
On Thursday, the minimum temperature was 23.9 degrees, four notches above normal. The maximum was 27, four notches below usual.
“The sky was overcast for most of the day. The absence of direct sunlight dragged the day temperature down. But the same clouds blocked the northwesterly winds and the night temperature went up,” said a Met official.
The same trend would continue at least for the next couple of days, he said.