The cyclone brewing in the Bay is set to make landfall in Andhra Pradesh on Tuesday night, the Met office has said.
Bengal might escape with heavy rain in some coastal pockets and thunderstorms in other areas, including Calcutta, between October 28 and 30.
At the time of landfall, Cyclone Montha — named by Thailand — will intensify into a severe cyclonic storm, unleashing winds of up to 110kmph.
Despite forecasts of limited impact, the Met office and Calcutta’s disaster management authorities will remain alert even after landfall. In recent years, cyclones have often brought heavy post-landfall rain to Calcutta, even after hitting land in other states.
As of Saturday morning, the system — then a depression over the southeast Bay, over 1,300km from Bengal — was expected to move north-northwestward as it approaches land. If it maintains that trajectory after landfall, it may move toward north Odisha.
A Met bulletin on Saturday stated: “It is likely to move nearly west-northwestwards, intensify into a deep depression by 26th and into a cyclonic storm over the southwest and adjoining westcentral Bay by Sunday morning. Thereafter, it is likely to move northwestwards, then north-northwestwards and intensify into a severe cyclonic storm by Tuesday morning.”
It added: “Continuing to move north-northwestwards, it is very likely to cross Andhra Pradesh coast between Machilipatnam and Kalingapatnam (in eastern Andhra) during evening/night of October 28 (Tuesday) as a severe cyclonic storm with a maximum sustained wind speed of 90-100kmph gusting to 110kmph.”
Cyclones have occasionally deviated from predicted paths — a recurve, in Met parlance. Should Montha recurve northeastward, it could move closer to the Bengal coast.
The last cyclone to bring heavy rainfall to Calcutta was Dana last October. It made landfall in Odisha’s Kendrapara, over 400km from the city, but clouds from it caused nearly 200mm of rain in Calcutta.
H.R. Biswas, head of the weather section at the Regional Meteorological Centre in Alipore, told Metro: “Winds from the system are unlikely to have any bearing on south Bengal. But as the storm moves inland, the northern part of its path may bring it closer to north Odisha, which borders south Bengal. Increased moisture incursion may then trigger rain in south Bengal.”