A well-marked low-pressure area over the Bay of Bengal intensified into a depression on Tuesday morning as it rolled towards the eastern coast with the likelihood of turning into a severe cyclonic storm, the IMD said.

In its bulletin, the India Meteorological Department (IMD) said the well-marked low-pressure area over the east-central Bay of Bengal moved west-northwestwards, concentrated into a depression and lay centred at 730 km southeast of Paradip in Odisha and 770 km south-southeast of Sagar island in West Bengal around 5.30 am.

The depression will further intensify into a cyclonic storm by October 23 and cross north Odisha and southern West Bengal coasts between Puri and Sagar in the early morning hours of October 25 as a severe cyclonic storm with a wind speed of 100-110 kmph, gusting to 120 kmph, it said.

Advising fishermen not to venture into the sea from October 23 to 25, the IMD warned that wind speed is likely to reach 60 kilometre per hour (kmph) along and off Odisha-West Bengal coasts and gradually increase thereafter.

The storm is likely to bring very heavy rainfall in southern West Bengal districts on October 24 and 25, the IMD said.

The weather system will bring heavy to very heavy rainfall with extremely heavy downpours at one or two places in the districts of South 24 Parganas, Paschim Medinipur, Purba Medinipur and Jhargram.

Heavy to very heavy rainfall is likely in Kolkata, Howrah, Hooghly, North 24 Parganas, Purulia and Bankura districts between October 24 and 25.

A deep depression is a more intense stage of a low-pressure system and typically precedes the formation of a cyclonic storm, according to the IMD.

The Odisha government has cancelled the leaves of all staff from October 23 to 25 in view of the cyclone forecast.

In a letter to all the departments, Special Relief Commissioner (SRC) DK Singh asked them to remain prepared to tackle the challenges of the impending calamity.