Arabian Sea has thrown up a deep depression (a step lower than a tropical cyclone) but it has moved away to be of any consequence for the Indian coast. Weather watchers will now shift focus to Bay of Bengal basin, with a circulation having developed over South Andaman Sea as of Wednesday. India Meteorological Department (IMD) expected a low-pressure area to develop here over the next two days. IMD has lately withdrawn a watch for intensification of the system. There is no consensus among global on its behaviour as it enters the larger Bay of Bengal. A couple of models suggest some intensification, but not powerful enough to lash the Andhra Pradesh coast, as was expected.
Opposite winds from western disturbances and lack of sufficient sea-surface temperatures (which fuels system intensity) are cited as unhelpful conditions. European Centre for Medium-Range Weather Forecasts sees a low-pressure area curling up from west of Sri Lanka and entering peninsular south later this week.
This may bring heavy rain to southern Tamil Nadu and adjoining Kerala and parts of Karnataka. Meanwhile on Wednesday, satellite imagery showed convective (rain-bearing) clouds rising over parts of south peninsular India, south Bay of Bengal, Andaman Sea and South Arabian Sea.
Extended forecast until the month-end said rains at many places over south peninsular India, Lakshadweep and Andaman and Nicobar Islands. This forecast valid for the next seven days said that heavy rainfall is likely over coastal Tamil Nadu.