Kolkata: The cyclonic circulation over the north Bay of Bengal and adjoining Bangladesh is likely to trigger the formation of a low-pressure area over northwest Bay of Bengal and its neighbourhood around Friday. With this system set to revive the monsoon flow, the city and parts of south Bengal are likely to get heavy to very heavy rain between Saturday and Monday.The cyclonic circulation already is casting its spell on the kind of cloud that took over the Kolkata sky along with the rain pattern on Tuesday. Kolkata’s sky had been gloomy since morning, with intermittent rain spells since afternoon minus the thunder and lightning strike during the previous thunderstorms. Met officials said that Tuesday’s rain spell was triggered by rain-bearing clouds formed under the influence of the cyclonic circulation and not by local thundercloud development.“The cyclonic circulation is already there, and under its influence we expect a low-pressure area around Friday. Also, the monsoon trough has come down closer to south Bengal. Once the low-pressure area forms, it would ensure the reactivation of the monsoon flow. We can expect some heavy to very heavy rain between Saturday and Monday in parts of south Bengal, including Kolkata,” said HR Biswas, head at RMC, Kolkata.Met officials said that once the low-pressure area forms, it would push up formation of the normal rain-bearing clouds rather than the convective clouds, which are formed locally and trigger more localised rain with thunder and lightning.
