Writers' Buildings waterlogged on Monday morning. Picture by Pradip Sanyal

The weather office has predicted more heavy rain till Tuesday afternoon, saying some respite is likely from the evening, provided the depression that flooded Calcutta on Monday moved northwest.

Officials at Alipore measured nearly 170 mm of rain between 8.30am and 8.30pm on Monday, but were yet to calculate if the 24-hour figures would outstrip the 211.6 mm recorded on September 22, 2006 — the second-highest ever.

Met officials couldn’t confirm the Calcutta Municipal Corporation’s claim that the rainfall from Saturday night till Monday morning had crossed 370 mm. A high figure would offer the civic body a handy excuse if the roads continue to stay waterlogged.

Civic officials were already warning of at least one more waterlogged day, saying even if there was no rain after Monday evening, the streets would not clear before Tuesday night.

The almost non-stop downpour since Saturday night has been caused by a pincer attack from the east and west, said G.C. Debnath, the director (weather section), Regional Meteorological Centre, Alipore.

The depression, which lay over the Chhattisgarh-Jharkhand border on Monday, has been sucking in water from both the Bay of Bengal and the Arabian Sea. A low-pressure zone off the Saurashtra coast has been feeding moisture to winds moving northeast towards the depression.

The weather officials said the depression moved from Orissa to north Chhattisgarh on Sunday night. It has shown no signs of weakening but is likely to continue moving northwest.

“We expect heavy rain in Calcutta and the districts of Gangetic Bengal till Tuesday afternoon,” Debnath said. “From the movement of the depression it appears that rainfall will increase over Bihar and north Bengal during the next 48 hours.”

The city recorded its highest single-day rainfall, 380 mm, on September 27, 1978. On July 3 this year, 160 mm fell in the five hours between 3.30am and 8.30am.

The Met officials said waterlogging is more common in September because the previous three months’ rain saturates the soil with water.

“Besides, the cyclone season begins in the last week of September. This is the time for low-pressure zones and depressions to form over the Bay,” an official said.

Compounding the waterlogging woes, large parts of Calcutta plunged into darkness as CESC, the private power utility, snapped electricity supply.

“We were forced to switch off supply because we have received distress calls from residents from all over the city that meter boxes and main switches were under water,” said a CESC spokesperson, adding that on requests from the CMC, CESC switched off power supply in Ultadanga as water had entered the pumping station.

But despite all the precautionary measures, Mukesh Yadav, a security guard of Fortune Apartment, on Shakespeare Sarani, was electrocuted on Monday night. Police said Yadav was rushed to SSKM Hospital, where doctors declared him dead.