Bengal weather: 7-day thunderstorm alert from April 20

Kolkata, April 18: A significant shift in weather patterns is on the horizon in West Bengal, with a developing upper-air cyclonic circulation and trough line likely to trigger a prolonged spell of thunderstorms, lightning, and gusty winds across the state.

Weather indications suggest that while the next 48 to 72 hours may see scattered and localised storm activity in a few districts, a more organised system is expected to take shape from April 20.

Between April 20 and April 27, all districts in the state are likely to witness recurring spells of thunderstorms and rain, raising the possibility of Kalbaisakhi-like conditions.

Though a detailed, date-specific forecast is yet to be issued, preliminary estimates indicate that storm activity could affect 50 to 75 per cent of areas in some districts of North and South Bengal, while other districts may see impact across 25 to 50 per cent of regions.

These weather events are expected to occur intermittently through the day, accompanied by lightning and strong, gusty winds.

Before April 20, the state is likely to experience predominantly humid conditions, particularly in Gangetic and coastal regions, where discomfort levels are expected to remain high.

In contrast, western districts may face dry and hot winds, similar to heatwave conditions. However, no official heatwave warning has been issued for the first phase of polling.

From April 20 onwards, the formation of a clearer synoptic system, marked by a trough line and upper-air cyclonic circulation, is expected to cause sudden cloud build-up even under clear skies.

This will significantly increase the likelihood of thunderstorms, lightning strikes, and gusty winds across the state.

During the first phase of elections, districts such as Alipurduar, Malda, North and South Dinajpur, Murshidabad, and Birbhum are likely to witness humid and uncomfortable weather conditions.

There is also a higher probability of thunderstorms developing in several areas during the afternoon or evening hours on polling day.

In contrast, the second phase of polling is expected to be more challenging due to rising temperatures, with a possible spike around April 29. However, the India Meteorological Department is yet to issue a detailed forecast for that period.

Meanwhile, on Saturday, South Bengal is expected to see a rise in temperature and discomfort as drier conditions begin to dominate.

However, districts such as Birbhum, Nadia, and East and West Bardhaman may witness thunderstorms with lightning and gusty winds reaching speeds of 30 to 40 km per hour.

Kolkata may also receive brief, scattered showers, though humid conditions are likely to persist through the weekend.

North Bengal, on the other hand, is expected to remain relatively comfortable, with most districts likely to receive rainfall.

Heavy showers are forecast in Darjeeling, Kurseong, and Jalpaiguri, along with winds of up to 50 km per hour. Rain activity in the region is expected to continue till Monday before gradually easing from Tuesday.