A depression over the Southwest Bay and adjoining area intensified into a well-marked low, said Bangladesh Meteorological Department (BMD) on Thursday.
The depression was centred at 12pm on Thursday about 1625 kms southwest of Chattogram port, 1570 kms southwest of Cox's Bazar port, 1500 kms southeast of Mongla port and 1505 kms southeast of Payra port, according to a Met office bulletin.
It is likely to intensify further and move in a west-northwesterly direction, the Met office said.
Maximum sustained wind speed within 44 kms of the deep depression centre is about 40 kmph rising to 50 kmph. However, sea will remain moderate near the coast.
All fishing boats and trawlers have been advised to come closer to the North Bay. They are advised not to venture into the deep sea.
