A fresh spell of thunderstorm activity is expected to sweep across large parts of West Bengal over the next four days, as per the latest forecast issued by the India Meteorological Department (IMD).

The weather office has attributed this impending weather pattern to the presence of an east-west trough extending from the cyclonic circulation over southeast Rajasthan and its neighbourhood to north Odisha.

This trough cuts across Madhya Pradesh, Chhattisgarh, and Jharkhand, and extends up to 1.5 km above mean sea level.

Further compounding the instability in the atmosphere is an upper-air cyclonic circulation persisting over north Bangladesh and its neighbouring regions, also extending up to 1.5 km above mean sea level.

According to IMD, favourable wind patterns combined with moisture incursion from the Bay of Bengal have set the stage for moderate to severe thunderstorm activity over several districts of West Bengal.

On May 3, thunderstorm activity accompanied by gusty wind reaching speeds of 50 to 60 kmph, lightning and light to moderate rainfall is likely to occur at one or two places over the districts of Purulia, Jhargram, Bankura, West Burdwan, West Medinipur and Hooghly.

The remaining districts of south Bengal may also witness thunderstorm activity, with lower wind speeds ranging between 40 and 50 kmph.

Thunderstorm activity with gusty winds of 40-50 kmph, lightning and moderate rainfall is likely at one or two locations in Malda and North Dinajpur. Other districts in north Bengal may experience thunderstorms with lightning and rain.

On May 4, Murshidabad, Nadia, North and South 24 Parganas and East Burdwan districts, where thunderstorms accompanied by gusty winds (40-50 kmph), lightning and light to moderate rain may occur at isolated locations.

The intensity and spread of the storm is set to widen on May 4, with all districts of north Bengal expected to witness thunderstorms with gusty winds (30-40 kmph), lightning and moderate rain.

The severity increases on May 5, with all districts likely to see gusty winds peaking at 40-50 kmph, lightning and rainfall.

The thunderstorm pattern will continue on May 5 as well, with North and South 24 Parganas, Murshidabad and Nadia districts expected to witness thunderstorm activity with gusty winds ranging from 30 to 40 kmph, lightning and light to moderate rainfall.

On May 6, the districts of Hooghly, Murshidabad and Nadia are forecast to face thunderstorms with gusty wind (30-40 kmph), lightning and moderate rain.

The remaining districts of south Bengal are expected to see thunderstorms with lightning and rain at one or two places. North Bengal may see gusty winds of 30-40 kmph, lightning and light to moderate rain.

According to the IMD, there may be damage to standing crops, vegetables and horticulture produce and open fields could see lightning strikes, posing risks to those outdoors. Unsecured structures could be damaged and traffic disruptions may occur, especially in urban areas.

During thunderstorm activity, people are urged to seek shelter in safe places and avoid taking cover under trees or electric poles.

They are also advised to stay away from water bodies and to regulate vehicular movement judiciously during storm activity.