A deep depression currently lies over the southwest and adjoining southeast Bay of Bengal, about 770 km east-southeast of Chennai, which is very likely to move west-northwestwards and intensify into a cyclonic storm by Tuesday evening, the Indian Meteorological Department (IMD) has informed.
The cyclonic storm is then expected to reach southwest Bay of Bengal off north Tamil Nadu, Puducherry and adjoining south Andhra Pradesh coast by Wednesday morning. It will continue to move northwestwards towards north Tamil Nadu-Puducherry and adjoining south Andhra Pradesh coasts in the subsequent 48 hours.
Under its influence, heavy rainfall is likely to occur in Tamil Nadu districts, including Cuddalore, Mayiladuthurai and Kancheepuram on Wednesday. Further, extremely heavy rainfall will be seen at isolated places in north-coastal Tamil Nadu, Puducherry and adjoining south-coastal Andhra Pradesh on December 9.
North interior Tamil Nadu and adjoining Rayalaseema will see isolated heavy to very heavy rainfall on 9 December. The showers will likely reduce to light to moderate rainfall at most places. But heavy to very heavy rainfall may be seen in north Tamil Nadu, Rayalaseema and south Andhra Pradesh on December 10.
Due to the development of a cyclonic storm, southeast Bay of Bengal will likely see squally winds reaching 50-60 kmph gusting to 70 kmph in the next 24 hours. It will reduce to 40-45 kmph gusting to 55 kmph subsequently on Wednesday.
Similar conditions will also be seen in southwest Bay of Bengal, increasing to 60-70 kmph gusting to 80 kmph from Tuesday evening. It will likely further increase, becoming Gale wind with speed reaching 70- 80 kmph gusting to 90 kmph from Wednesday morning and 80-90 kmph gusting to 100 kmph between Wednesday and Thursday. It would decrease thereafter gradually.
Squally winds with the speed reaching 40-50 kmph gusting to 60 kmph are also likely to commence along and off Tamil Nadu, Puducherry, south Andhra Pradesh and north Sri Lanka coasts from Wednesday morning, becoming 50-60 kmph gusting to 70 kmph from the evening, 70-80 kmph gusting to 90 kmph from Thursday evening to Friday morning.
It is likely to reduce gradually to 50-60 kmph gusting to 70 kmph by afternoon of Saturday and then to 40-50 kmph gusting to 60 kmph by Saturday night.
The Gulf of Mannar will also experience squally winds with the speed reaching 40-50 kmph gusting to 60 kmph from Thursday evening, becoming 50-60 kmph gusting to 70 kmph from Friday evening to Saturday morning. It is likely to reduce gradually thereafter.
Due to this, fishermen have been advised not to venture into the southeast Bay of Bengal on Tuesday, southwest Bay of Bengal from Tuesday to Saturday and along and off the Sri Lanka coast from Tuesday to Friday.
They have also been told to steer clear along and off the Tamil Nadu, Puducherry and South Andhra Pradesh coasts and the Gulf of Mannar from Tuesday to Saturday 07th-10th December. "Fishermen out at sea should return to the coast or move to the safe area," the IMD said in a release.