Kolkata Rains: What Led to the Torrential Downpour? Explained

Kolkata: Kolkata witnessed one of its heaviest rainfalls in recent history on 22–23 September, with over 251.4 mm recorded in just 24 hours, more than the city received during the entire month up to that point.

Here’s what triggered the deluge and led to the heavy rainfall in Kolkata, West Bengal.

Reasons Behind the Torrential Rains    

Tropical Disturbance 98B

The primary cause was a tropical disturbance over the Bay of Bengal, known as system 98B. It moved northwest and made landfall near Kuakata, Bangladesh, intensifying rainfall across the Gangetic West Bengal region, especially in Kolkata and its surrounding areas.

Low-Pressure Area Formation

A low-pressure system developed over the northwest Bay of Bengal and adjoining coastal areas of Gangetic West Bengal and North Odisha. This system persisted for over 24 hours, fueling intense convective thunderstorms.

Convective Thunderstorms

A brief but intense downpour driven by convective activity, common in tropical systems. Experts warn that such episodes are growing more frequent amid shifting climate patterns.

Climate Change Impact

Scientists have observed a trend indicating fewer rainy days but more intense rainfall. In other words, when it rains, it pours. Kolkata received 2,663% more rain than its long-term daily average in just one day, a truly alarming figure.

Areas Affected the Most

The sheer volume of rain overflooded drainage systems, affecting areas like Ballygunge, Kalighat, and Jodhpur Park. Metro and railway services were disrupted, and several deaths were reported due to electrocution.

Commuters are advised to avoid the following roads: Maa Flyover, Theatre Road, AJC Flyover, Amherst Street, Kakurgachi Underpass, Amir Ali Avenue, Hospital Road, Lenin Sarani, AMC Bose Road, Bidhan Sarani, MG Road, CR Avenue, ATM Road, and Alipore Road.

The Kolkata airport authority and flight carriers have issued an alert and advisory as heavy rains are expected in the coming hours.

Kolkata Comes to a Standstill

For the first time, a cloudburst occurred in Kolkata. Between 2 AM and 6 AM, the city received 300 mm of rain. At least seven people have died so far. Hospitals, flights, cabs, trains, metros, buses, and boats have come to a halt. The drainage system has collapsed. Several Durga Puja pandals have been damaged.