KOLKATA: A thunderstorm hit parts of south Kolkata and brushed past the rest of the city on Saturday evening. It was accompanied by gusty winds, which touched a maximum speed of 52km an hour and an 18km-tall column of cumulonimbus cloud which shrouded the city in darkness. Though the cloud cover and the wind looked threatening, what followed was just a light drizzle in some parts of the city.
The giant cloud column, which had sailed towards Kolkata from
Baripada in Odisha cutting across West Midnapore, East Midnapore, Howrah, and North and South 24 Parganas, brushed past the southern fringes of the city and moved towards the Bay of
Bengal, according to the Met office. But the conditions that had led to the formation of the cloud and the thunderstorm still persist and could result in another thunderstorm on Sunday, said the
Regional Meteorological Centre (RMC), Alipore.
Even though the thunderstorm hit with a wind speed of 52 km/hr, it wasn’t a squall, explained weathermen. Neither did it last the mandatory one minute nor did the wind speed reach its peak in a gradual ascent. “It was a sudden gust which lashed Kolkata and then stopped. But the conditions remain conducive for another thunderstorm on Sunday,” said GK Das, director of RMC.
Conditions had been turning favourable for a thunderstorm since Wednesday. Moisture incursion from the sea was coupled with a cyclonic circulation over Jharkhand. On Saturday, a strong wind from the surface (wind seer) swirled up to the upper layers. “All these conditions were ideal for the building up of a thunderstorm. Unfortunately for Kolkata, it grazed the southern part of the city. The exceptionally tall cloud column was formed due to the high vertical wind speed from the surface,” explained Das. But it started dissipating once it crossed Kolkata and moved towards the sea.
“Cool winds from the sea help to disintegrate such clouds,” Das added. The city is yet to be lashed by a proper nor’wester this season. It has had at least three near-misses. Last Sunday’s thunderstorm was not a squall either since it had a lower wind speed. But conditions for a nor’wester are building up. When an area has moist, warm conditions and another turns dry and hot, nor’westers happen. On Saturday, too, south Bengal and the Jharkhand region had similar conditions that led to the thunderstorm,” said Das.
