An alert has been sounded in the ports areas of Chattogram, Cox’s Bazar, Mongla and Payra after Cyclone ‘Yaas’ over the east-central Bay of Bengal and adjoining areas moved north-northwestwards in the past six hours and intensified into a severe cyclonic storm.   Around 6 am on Tuesday, the severe cyclonic storm was centred about 575 km south-southwest of Chattogram port, 520 km south-southwest of Cox’s Bazar port, 515 km south-southwest of Mongla port and 480 km south-southwest of Payra port, the Met office said in a special bulletin.   Due to favourable atmospheric conditions, the severe cyclonic storm is likely to intensify further, move in a north-northwesterly direction and may reach the northwest bay by May 26 early morning, it said. Read: Khulna preparing for cyclone Yash   Maximum sustained wind speed within 64 kms of the severe cyclone centre is about 89 kmph rising to 117 kmph in gusts or squalls. Sea will remain high near the severe cyclone centre, the Met office said.   Also read: Cyclone Yaas: Maritime ports in Bangladesh asked to hoist signal No 2   Maritime ports of Chattogram, Cox’s Bazar, Mongla and Payra have been advised to keep hoisted distant warning signal number two (r) two. All fishing boats and trawlers over the north bay and deep sea have been advised to take shelter and remain in shelter until further notice.