Heavy rainfall lashed isolated places over South Coastal Andhra Pradesh and adjoining Rayalaseema, while light to moderate rainfall was reported at isolated places over Tamil Nadu during the 24 hours ending on Wednesday morning, as a spill-over low-pressure area from an erstwhile depression over the Bay of Bengal crossed the North Tamil Nadu-South Andhra Pradesh coast.

The India Meteorological Department (IMD) said coastal Andhra Pradesh received most of the heavy rainfall during the period, with Tada and Sullurpeta (both Nellore district) and Satyavedu in Chittoor in Rayalaseema recording nine cm each.

Reports on Wednesday morning said neighbouring centres in the interior parts of Tamil Nadu, too, have received moderate to heavy rain.

Thunderstorms over AP coast

Afternoon satellite pictures showed the heaviest thunderstorms staying put over an area over Coastal Andhra Pradesh, bounded by Gudur, Nellore, Mittapaalem, Kadapa, Kodur and Tirupathi. The rest of the clouds had spilled into Vellore in Tamil Nadu and Chikkabellapura in adjoining South Interior Karnataka.

The IMD has pushed by at least a day to Friday the arrival of a fresh cyclonic circulation over the North Andaman Sea. It is likely to be scooped up by a passing western disturbance and dumped over the West Bengal coast, according to early forecasts.

It may also throw down a rain-driving trough deep towards the South-West, to the Sri Lanka coast, while grazing the southern fringes of the Tamil Nadu coast and Kerala.

Most ‘trolled’ depression

Meanwhile, the erstwhile depression off South Andhra Pradesh and North Tamil Nadu and one of the most trolled due to its histrionics, managed to end its enforced wait over the seas and cross the South Andhra Pradesh coast.

The IMD had said it will spark light to moderate rainfall at a few places over North Tamil Nadu, Puducherry, South Coastal Andhra Pradesh and Rayalaseema.

This was evidently far below what it was expected to deliver during its build-up phase, often accompanied to one side by a menacing line-up of full-blown thunderstorms.

It is unusual for a depression to wither away in this manner close to the coast, though not outrightly a freak given how it is vulnerable to the whims of the dominant weather features prevailing over the land it aims to cross.

Slow movement, stall

Its movement towards the coast was very slow to start with, but picked up later, even as it ran into opposing cool and dry winds upcountry.

A visiting western disturbance over North-West India had pushed the seasonal anti-cyclone with higher pressure and dense air towards the East, whose southern flanks began to douse the fiery thunderstorms around the depression’s periphery.

This caused it to slow even more and gradually stall over the waters, though managing to break out of the gridlock once. But this was clearly not enough.

Night temperatures have been appreciably below normal over Tamil Nadu, Puducherry and Karaikal, from cooler winds blowing over land from the North-West India, though they have been currently displaced by warmer winds blowing from the seas on the trail of the low-pressure area.