North-east monsoon consolidating along south-east coast

Two days into its onset, the north-east monsoon has been steadily consolidating its presence along the country's south-east coast.

The seasonal weather system has been riding piggyback on an upper level cyclonic circulation, which has since moved southward along the Tamil Nadu coast to a perch over Southwest Bay of Bengal.

RAIN ALERT

According to the UK Met Office weather model, the system was expected to cross land and the South Peninsula towards Coastal Karnataka over the next few days.

A weather warning issued by India Meteorological Department (IMD) on Sunday said that isolated heavy to very heavy rainfall would occur over Coastal Andhra Pradesh during the next two days.

It would be isolated heavy over Tamil Nadu, Interior Andhra Pradesh, South Coastal Orissa and Kerala during this period.

The 24 hours ending Sunday morning said that widespread rainfall was reported from Coastal Orissa and Andhra Pradesh while it was fairly widespread over the rest of South Peninsular India.

‘LOW' BREWING

The IMD said that the first full-fledged low-pressure area of the season may emerge over South Andaman Sea by Wednesday.

This would be remnant of a tropical depression located across India's territorial waters in the Gulf of Thailand on Sunday.

It was headed in a west-northwest direction to move for its onward hop into the South Andaman Sea.

A number of weather models surveyed - including Canadian Meteorological Centre, US National Centres for Environment Prediction/Global Forecast System and European Centre for medium-Range Weather Forecasts – indicated its generally west-northwest track and intensification into a likely depression.

DIFFERING VIEWS

The models differed in their outlook for its landfall, positing it along the Southeast Coast at any point from Central coastal Tamil Nadu to the Coastal Andhra Pradesh.

The US Navy's NGP proved the odd model out by suggesting that the system might track straight to the west, cross northern Sri Lanka and weaken but proceed to curl into extreme South Indian Peninsula.

The International Research Institute (IRI) for Climate and Society at Columbia University said in its six-day outlook ending Thursday that very heavy recorded rainfall is likely over South Coastal Andhra Pradesh, Central Tamil Nadu coast and adjoining interior.

ABOVE NORMAL

The region around Chennai and South Coastal Andhra Pradesh may receive up to 60 per cent above the normal rainfall during this six-day period, it said.

‘Wetter than normal conditions' have been forecast for North Coastal and Interior Tamil Nadu.

But the Climate Prediction Centre of the US National Weather Services indicated that monsoon northeasterlies and easterlies over the Bay of Bengal would give way to a burst of westerlies turning southeasterlies from Friday.

This might rob the Tamil Nadu coast some of the rains, though they are expected to fall over Kerala as the southeasterlies mop up moisture from the Bay and blow in as westerlies to northwesterlies to complete the circulation in the larger trough.

CLOUD IMAGERY

On Sunday, satellite imagery showed convective clouds over parts of West-central, Northeast and Southwest Bay, South Andaman Sea, Southeast Arabian Sea, Orissa, South Chhattisgarh, Andhra Pradesh, Kerala and Tamil Nadu.

This is expected to trigger widespread rain or thundershowers over Coastal Andhra Pradesh.

It would be fairly widespread over Tamil Nadu, Andhra Pradesh, Kerala, Coastal Orissa, South Chhattisgarh and Andaman and Nicobar Islands.

Scattered rain or thundershowers would occur over South Karnataka and Lakshadweep on Monday and increase thereafter.

Isolated rain or thundershowers would also occur over the Northeastern States on Monday and increase thereafter.

An extended forecast until Friday said that fairly widespread rainfall activity would occur over Andhra Pradesh, Karnataka, Tamil Nadu, Kerala and Andaman and Nicobar Islands.