CHENNAI: The depression over southeast Bay of Bengal over Andaman and Nicobar Islands is very likely to intensify into a deep depression during the next 24 hours and then into a cyclonic storm in the subsequent 24 hours, the Meteorological department here has said.The depression over southeast Bay of Bengal moved further northwards with a speed of about 10 kmph during the past six hours and lay centred over southeast Bay of Bengal, Director, Area Cyclone Warning Centre, S Balakrishnan said here today.Briefing reporters here, he said the depression lay about 260 km west-northwest of Car Nicobar and 310 km south-southwest of Port Blair and 1180 km south-southeast of Visakhapatnam."It is very likely to intensify into a deep depression during the next 24 hours and into a cyclonic storm in subsequent 24 hours," he said.He also referred to the presence of an upper air circulation and said there could be spells of rain at isolated places in Tamil Nadu and Puducherry in the next 48 hours.