New Delhi, The India Meteorological Department (IMD) said on Saturday that the deep depression over the Bay of Bengal has intensified into a cyclonic storm named ‘Amphan'.

"The deep depression over Southeast Bay of Bengal and the neighbourhood remained practically stationary during the past six hours and rapidly intensified into the cyclonic storm ‘Amphan'," IMD scientist R.K. Jenamani said.

The cyclonic storm is likely to intensify further into a ‘severe' cyclonic storm during the next 12 hours and into a ‘very severe' cyclonic storm by May 18.

"It is very likely to move north-northwestwards initially till May 17 and then re-curve north-northeastwards across northwest Bay of Bengal towards West Bengal and adjoining Odisha coasts during May 18-20," the weather department added.

Private forecaster Skymet Weather also echoed similar predictions. "It is expected to make landfall over Gangetic West Bengal on May 20, although some models indicate its movement towards Bangladesh," said Mahesh Palawat, Vice President at Skymet.

"Either way, Gangetic West Bengal is going to get heavy rains and gale force winds. Sea will be very rough," he added.

The coastal state governments have warned fishermen not to venture into the sea. Cyclone shelters have been readied and areas requiring evacuation of people have been identified.