Cyclone 'Helen' would cross the south Andhra Pradesh coast near Kavali on the night of November 21, the IMD said.
The deep depression over west-central Bay of Bengal would intensify into a cyclonic storm in the next few hours and to a severe cyclonic storm in the next 24 hours, it said.
Moving westnorthwestwards for some time and then westsouthwestwards, it would cross south Andhra Pradesh and adjoining north Tamil Nadu coasts between Chennai and Ongole close to Kavali around the night of November 21, the IMD said.
IMD further warned of heavy to very heavy rainfall at a few places with isolated extremely heavy rainfall over coastal Andhra Pradesh from today onwards.
Squally winds with speed of 5565 kmph gusting to 75 kmph would prevail along and off north Andhra Pradesh and north Tamil Nadu and Puducherry coasts, it said, adding sea conditions would be very high along and off Andhra Pradesh coast.