Kolkata, Sep 2 : A powerful squall front swept across south Bengal districts, including Kolkata, bringing torrential rain, lightning, and gusty winds.

Incessant rain accompanied by thunderstorms was reported from several areas in South Bengal since Monday night.

The system is likely to remain effective for another 12 hours, said the Meteorological (MeT) Department. As a result, heavy rain accompanied by thunderstorms is likely in the next 12 hours in the south Bengal districts, especially in Kolkata, Howrah and Hooghly.

Fishermen have been asked not to venture into the sea from Tuesday to Thursday.

A squall front is a convergence zone where massive cumulonimbus clouds form in a linear pattern, triggered by the collision of easterly and westerly winds. Such fronts often result in heavy downpours, thunderstorms, microbursts and cloudbursts.

According to meteorologists, a squall front forms within a very short period. As a result, darkness suddenly descends and conditions are created for lightning, heavy storms and rain.

On Monday night, the MeT Department issued a red alert for severe thunderstorms and lightning accompanied by intense rain for Howrah, Hooghly and Kolkata.

"A cyclonic circulation is present over the Bay of Bengal near the Myanmar coast. Due to its influence, a low-pressure area will form in the sea within the next 24 hours. The monsoon axis has shifted again in the state. It extends over Digha to the northeast Bay of Bengal. Due to this, there is a possibility of heavy rain in some areas of South Bengal. The sea will remain rough due to the influence of the low-pressure area," said a MeT Department official. As a result, rain will intensify over South Bengal from Tuesday onwards.

Rain will continue in North Bengal as well. There is a possibility of heavy rainfall in some northern districts till next Sunday. Light to moderate rainfall is likely in all the remaining districts, said the MeT officials.

The maximum temperature in Kolkata on Monday was 34.2 degrees Celsius, 1.7 degrees above normal. The minimum temperature was 28.2 degrees Celsius, 1.6 degrees above normal.

/IANS