A brief lull in monsoon activity was broken by a fierce spell of rain on Thursday afternoon, leaving several city roads waterlogged and traffic stalled.
The rain was not uniform. When Ballygunge was getting drenched, parts of Kasba were dry.
In just a couple of hours, between 1pm and 3pm, Kalighat got 103mm of rain, according to figures obtained from the drainage pumping stations of the Kolkata Municipal Corporation. Ballygunge got 81mm, Mominpore 80mm and Taratala 78mm.
The Met office recorded a little over 60mm in Alipore, which serves as the official logbook for Kolkata, in the same period.
In Met parlance, 60mm of rain in 24 hours qualifies as heavy.
The intensity of the rain was more in south and central Kolkata, compared to the north and northern fringes, said Met officials.
Thanthania and Maniktala got around 10mm of rain in the same period.
Around 1pm, the showers had reduced visibility in Esplanade, New Market, Park Street and adjoining areas. By 2pm, Theatre Road, Camac Street, Cathedral Road, Outram Road and several other roads were under almost knee-deep water.
Many pedestrians were caught unawares by the showers. Around 2pm, a group of students walked barefoot on Park Street, holding their shoes in their hands.
Similar scenes played out on Camac Street and Theatre Road. A sedan was half-submerged on JL Nehru Road around 2.20pm.
Vehicles moved at a snail’s pace on major thoroughfares.
Historian Sugata Bose was supposed to deliver a talk at Alipore Jail Museum, less than 3km from his Elgin Road home, from 6pm.
He was delayed by 45 minutes. “I had to walk almost a kilometre as nothing seemed to be moving,” Bose said.
A Gariahat resident took 45 minutes to drive to Lake Mall, 2km away, instead of the usual 10-15 minutes in the evening rush hour.
Vehicular movement on Chowringhee, JL Nehru Road, Dufferin Road, Nasiruddin Road, Sarat Bose Road, Park Street, Alipore Road, Camac Street, Burdwan Road, Diamond Harbour Road, Theatre Road, AJC Bose Road and Park Circus seven-point crossing was worst affected after 1pm.
The police said it took several hours to normalise traffic. Traffic slowed on the Parama flyover because of congestion and waterlogging at Park Circus.
The heavy rain coincided with high tide in the Hooghly, forcing the civic body to shut the lock gates. The gates were closed from 11.45am to 4.15pm, said a KMC official.
He said the high volume of rain in a short span of time, together with high tide, prevented the water from being drained out.
The volume of rain far surpassed the drainage capacity. Kolkata’s underground drainage network is designed to prevent waterlogging only if it rains up to 6mm in an hour, said an engineer.
A Met official attributed the showers to a combination of heat and humidity.
“There is a cyclonic circulation over the northeast Bay of Bengal. There was sufficient moisture incursion. There was sufficient heating as well. Together, the heat and humidity caused very strong thunderclouds which emptied themselves over Kolkata,” said G.K. Das, director, India Meteorological Department, Kolkata.
“But since the system was not very powerful, the rain was not uniform.”
An imminent low-pressure area over the Bay of Bengal can bring more rain to Kolkata over the next few days, Das said.
“The system is expected to take shape over the northwest Bay, closer to the Bengal-Odisha coast, around September 4,” he said. “In the run-up to the system, Kolkata is likely to get more rain.”
But in the next couple of days, the weather will be hot and sweaty when it does not rain.