The depression over southeast Bay of Bengal in Andaman and Nicobar Islands developed into a deep depression and intensified into a cyclonic storm "Vardah."
The system is very likely to intensify into a severe cyclonic storm during the next 24 hours and it is expected to make a landfall in Andhra Pradesh coast on December 12, the Met Department said in Chennai on Thursday.
Citing a less marked upper air cyclonic circulation over south Tamil Nadu and neighbourhood, the department said rain or thundershowers are likely to occur at isolated places over Tamil Nadu and Puducherry in the next 48 hours.
In a bulletin, the department said the depression over Southeast Bay of Bengal yesterday moved westward and concentrated into a deep depression.
It further moved northwestwards and concentrated into a cyclonic storm, "Vardah" over Southeast Bay of Bengal early today, it said.
It lay about 1040 kilometres of Visakhapatnam, 360 kilometres Northwest of Car Nicobar and 240 kilometres West-southwest of Port Blair.
"The system is very likely to intensify further into a severe cyclonic storm during next 24 hours," the department said.
The cyclonic storm is very likely to move nearly Northwards for some more time, then Northwestwards and cross Andhra Pradesh coast between Nellore and Kakinada around forenoon/noon of December 12.
"There is possibility of slight weakening of the system before landfall," the department said.
Light to moderate rainfall is expected at many places with isolated heavy falls with squally winds over coastal Andhra Pradesh from 11 December evening, the department said.