3 weather systems merge to sink Kolkata – Times of India

Kolkata News
KOLKATA: An unexpected movement of a cyclonic circulation from northwest Bay of Bengal and the adjoining areas of the Bengal-Bangladesh coast towards Kolkata and south Bengal triggered an incessant deluge early on Monday that lasted more than eight hours, leaving most areas of the city and its surrounding districts waterlogged and paralyzing life across south Bengal even as the Met office predicted the rain to continue till Tuesday.
With the city recording 142 mm rain on Monday, it turned out to be the rainiest September day in Kolkata since September 25, 2007 when the city received 174.4 mm rain.

The circulation that had resulted from the merger of two such systems, one over south Bangladesh and another over northwest Bay, gained strength and moved into south Bengal around Sunday midnight. It then started moving towards Kolkata and stood right over the city at around 3 am that launched an intense spell of rain which continued till Monday noon.
It was aided by the monsoon trough, that, too, passed through the city and added to the rain intensity. “It was a strong system that remained stationed over Kolkata for more than eight hours and moved very slowly, leading to an extended spell of rain that kept getting heavy intermittently. It started moving away from Kolkata after 12 noon on Monday, when the rain started losing intensity. But sporadic showers will continue in Kolkata and south Bengal till at least Tuesday, with occasional heavy rain,” said Regional Meteorological Centre (RMC) director GK Das.
Along with Kolkata, Howrah, North and South 24 Parganas, Hoogly, Nadia and East Midnapore, too, received heavy rain on Monday.
The system is expected to move westward towards Jhargram, West Midnapore, Purulia and Bankura, causing heavy rain at these districts on Tuesday as it heads towards Jharkhand.
The heavy rain early on Monday was accompanied by lightning and thunder that kept striking at regular intervals. “The circulation had formed at a height of 5.8 km and extended further vertically with strong winds around it. It was a giant cloud column with clouds circulating at a great speed, leading to friction with each other that caused lightning and thunder,” said Das.
A meteorologist explained that a cloud with a negatively charged bottom and a positively charged top triggers lightning. “These electrical fields become incredibly strong, with the atmosphere acting as an insulator between them in the cloud,” he said.
As the circulation moves westward, rain could lose intensity in Kolkata but the districts of Jhargram, West Midnapore, Purulia, Bankura and parts of South 24 Parganas could be lashed by heavy rain on Tuesday, said deputy director-general of meteorology Sanjib Bandopadhyay. “Water-level may rise in rivers of south Bengal and we apprehend damage to crops. Fishermen have been asked to stay away from rivers and the sea. People are advised to stay indoors to protect themselves from lightning strikes,” said Bandopadhyay.
There could be another deluge later this week, as another cyclonic circulation forms over northeast Bay of Bengal on September 25. “It will approach Odisha-Bengal coast but it’s still too early to predict its subsequent course,” said Das.

Source: https://timesofindia.indiatimes.com/city/kolkata/3-weather-systems-merge-to-sink-kol/articleshow/86376481.cms