A heavy spell of rain, accompanied by bolts of lightning, lashed the city and its fringes on Friday afternoon, flooding roads and forcing people indoors or under shelter. It marked the third consecutive day when a bright, sunny morning gave way to stormy, rain-soaked conditions by afternoon — but Friday’s spell was the most intense.
The Met office recorded 69mm of rain, most of it between 2pm and 4pm. In meteorological terms, 60mm or more in 24 hours qualifies as “heavy” rainfall. Some neighbourhoods saw even higher figures: Jodhpur Park received 83mm, Ballygunge 58mm, and Mominpore 55mm. Light showers continued into the evening.
Behind the downpour
Friday afternoon’s rain was blinding for nearly 30 minutes.
A Met official said the downpour was driven by atmospheric conditions typical of a retreating monsoon.
“Strong cloud convergence occurred due to the interaction between dry winds from the northwest and moist winds from the Bay of Bengal,” the official said. An upper-air cyclonic circulation over south Bangladesh and the adjoining north Bay added to the intensity, he said.
Monsoon withdrawal
On the same day, the Met department issued a bulletin stating that the retreat of the southwest monsoon was likely to begin in Bengal within the next “three to four days”.
According to the bulletin, the monsoon had further withdrawn from the remaining parts of Gujarat, most of Madhya Pradesh and Uttar Pradesh, and parts of Maharashtra and Bihar.
Favourable conditions exist for further withdrawal from the rest of these states, as well as “entire Jharkhand and Chhattisgarh, and some parts of West Bengal, Sikkim, Odisha, and Telangana” in the next few days, it stated.
In Calcutta, more showers are expected on Saturday, with Sunday likely to be drier. The forecast predicts clearer skies from Monday, with no rain alerts in the seven-day outlook issued on Friday.
The usual date for the monsoon’s withdrawal from Calcutta is around October 10.
Waterlogged roads
The heavy rain, combined with a high tide in the Hooghly, led to waterlogging across the city. By 4.30pm, major roads like Central Avenue, Park Street, Theatre Road, Camac Street, and stretches of AJC Bose Road were under ankle-deep water.
Several roads remained flooded beyond 7pm, with traffic disruptions continuing into the evening. An officer from the South Traffic Guard said roads near Birla Planetarium, Cathedral Road, and Camac Street were still inundated even late in the evening.
Commuters had a tough time navigating the city. A two-wheeler rider who travelled from Ruby to Chandni Chowk said he had to wade through flooded stretches of Shakespeare Sarani, Camac Street, and JL Nehru Road. Another commuter from Paikpara reported similar scenes in the northern parts of the city.
High tide halts drainage
Officials from the Kolkata Municipal Corporation (KMC) attributed the waterlogging
to the coincidence of heavy rain with a high tide in the Hooghly.
“We couldn’t open the sluice gates between 1.30pm and 5.45pm due to the tide. The peak of the high tide occurred shortly after 3pm,
and the gates must remain shut for about two hours on either side of that,” said a KMC official.
KMC engineers explained that opening the gates during high tide would allow river water to backflow into the city’s drainage system, worsening the flooding.
Calcutta’s stormwater drains eastward into the Bidyadhari river and westward into the Hooghly.
“Since the Hooghly sluice gates were shut, we started operating pumps at the drainage stations to divert the water towards east Calcutta,” the official said.