A nor’wester, the second in four days, brought relief from sultry conditions on Thursday evening.
At 5.15pm, the Met office recorded a wind speed of 68kmph in Dum Dum.
At least five flights to Kolkata had to be diverted because of the stormy weather, said an airport official.
The rain that followed was uniform across the city, although a Met official said the volume was more in the northern parts and on the northern fringes.
A nor’wester clocking 84kmph struck the city on Monday evening, the strongest storm so far in the squall season. The howling winds uprooted trees, tore off advertisement banners from hoardings, choked traffic and disrupted trains and flights.
In comparison, Thursday’s storm was milder but it brought the much-wanted relief from the heat and humidity.
Two readings best explained that relief.
“Around 4.30pm, the Celsius was around 30 degrees. Around 5.30pm, it dipped to 23 degrees,” said a Met official.
The city, reeling under scorching conditions, cooled down after Monday’s storm. But the relief was short-lived. Typical of May, the conditions had become difficult from Wednesday morning again.
The minimum relative humidity on Thursday was 52 per cent, meaning the moisture content in the air was close to 60 per cent for most of the day. Even a relatively lower maximum temperature — 33.3 degrees, three notches below normal — seemed much sultrier because of the high moisture content.
“The rain-bearing thunderclouds came from the Chhotanagpur Plateau region, via Bankura, Birbhum, Bardhaman, Howrah and Hooghly,” said G.K. Das, director, India Meteorological Department, Kolkata.
“Thunderstorms were reported from the districts in the morning as well. The clouds travelled towards Murshidabad and Nadia and some of them reached North and South 24-Parganas as well. But they skipped Kolkata. In the evening, the clouds reached Kolkata,” said Das.
A cyclonic circulation over Uttar Pradesh and a resultant trough of low pressure from Uttar Pradesh to Telangana were drawing a lot of moisture from the Bay, he said.
At least five flights had to be diverted from the Kolkata airport, four to Ranchi and one to Bhubaneswar, on Thursday evening, said an airport official.
The storm and the rain slowed traffic on some major thoroughfares in the city.
The Met office had predicted an enhanced spell of thunderstorm in south Bengal till May 20.
“One more spell is likely in the city over the next two days,” said Das.