Chennai, Nov 24 : A deep depression over Southwest Bay of Bengal has intensified into cyclonic storm Nivar and lay centred about 410 km East-southeast of Puducherry and 450 km southeast of Chennai, said the India Meteorological Department on Tuesday. According to the weather department, over the next 24 hours it is likely to intensify further into severe cyclonic storm and cross Tamil Nadu and Puducherry coasts between Karaikal and Mamallapuram around Wednesday 8 p.m. as a Severe Cyclonic Storm with a wind speed of 100-110 kmph gusting to 120 kmph. Squally weather with wind speed reaching 80-90 kmph gusting to 100 kmph is likely to prevail over Southwest Bay of Bengal and along & off Tamil Nadu, Puducherry coast on Tuesday. On Wednesday, squally weather with wind speed reaching 100-110 kmph gusting to 120 kmph is likely to prevail over Southwest Bay of Bengal and along and off Tamil Nadu and Puducherry. Sea condition is likely to be very rough to high over these regions. Fishermen are advised not to venture into these sea areas for the above mentioned period. /IANS