Kolkata sweats its way through longest spell without a kalbaisakhi since 2010 – Times of India

Kolkata: This April has so far been the driest in Kolkata since 2010 and the city is now in the middle of the second longest non-winter rainless spell in 16 years. It hasn’t rained a drop in the city since February 28, though a thunderstorm is likely to strike by Friday. In 2010, the city had received the season’s first thunderstorm on April 27, following a dry period that had started on March 29.
In 2006, Kolkata had no thunderstorm or rain from February 1 to April 13 – the longest dry pre-monsoon period in recent years. A decade later, in 2016, Kolkata had received a thunderstorm on April 1 that led to a dry period that lasted till May 4.
There hasn’t been a rainless April in the last two decades though thunderstorms have often been few and precipitation low, said the Regional Meteorological Centre.
“There has been no rain since March 1 and the mercury has been soaring past 35°C. There are several reasons behind this, including a strong high-pressure zone over central India that has been generating scorching westerly winds since March. This has prevented the formation and movement of western disturbances that lead to low-pressure troughs in the region. This season, no western disturbance has sailed past Kashmir,” said RMC director G K Das.
The good news is that the high-pressure zone above central India has now weakened, allowing a western disturbance to generate a north-south low-pressure trough between Madhya Pradesh and Telangana. “There are clouds over central India and these have started floating into the western districts of Bengal,” added Das.
Thunderstorms with a wind speed of 30-40 km/hr struck Jhargram, West Midnapore, Purulia, Bankura and West Burdwan on Thursday evening. “We expect the clouds to travel to south Bengal and reach Kolkata for a thunderstorm and rain by Friday. The cloud masses that have formed over Jharkhand are strong enough to sail deep into south Bengal. But if it doesn’t rain by Friday, the dry spell could linger for another four-five days,” said Das.
Three factors contribute to a squall or a thunderstorm — moisture incursion from the sea, heating of land in Gangetic Bengal and Jharkhand and cyclonic circulations. None of these has been happening this season, pointed out Das. “It is a normal phenomenon, though. In some years, the frequency of the contributing factors go down. So, thunderstorms turn rarer,” said Das.
A 20-year analysis of the city’s weather puts the average April mean temperature (maximum) at 30.2°C. It rises to 30.7°C in May, which is the hottest month of the year. The city receives around a dozen thunderstorms between Mar-ch and May on an average.