The India Met has forecast heavy rain over south coastal Andhra Pradesh, Tamil Nadu, Puducherry and Kerala over the next four days.
This is attributed to the presence of a low-pressure area (having weakened from being a well-marked ‘low’ from overnight) over West-Central Bay of Bengal off Andhra Pradesh coast.
Update:
Rainfall occurred at most places over coastal Andhra Pradesh and at a few places over Rayalaseema and Kerala, IMD said.
It was isolated over Telangana, Lakshadweep, Tamil Nadu and south interior Karnataka. Chennai and neighbourhood remained cloudy and sunny alternatively.
Over Tamil Nadu, the rain was concentrated to the South with the heaviest being reported from Virudhunagar district after clouds drifting in from the Gulf of Mannar. The chief amounts of rainfall (in cm) were: Sivakasi-10; Virudhunagar-9; Rajapalayam-8; Kovilankulam, Tirumayam, Tirumangalam, Illuppur, Tondi, Illayangudi, and Surangudi-6 each; and Aruppukottai; Marungapuri; Kalugumalai; and Sattur- 5 each.
Pacific typhoon The European Centre for Medium-Range Weather Forecasts has suggested that weather conditions in the Bay of Bengal are likely to wax and wane with the formation and track of a typhoon in the West Pacific over the next few days.
The US Centre for Climate Prediction is of the view that overall, this might lead to setting up normal to above normal monsoon conditions over the Tamil Nadu and Puducherry coast (apparently the four-day period from tomorrow).
But later, the US National Centres for Environmental Prediction sees an anomaly in which weather-friendly trough leaving the Tamil Nadu coast to align along the West Coast.
This would trigger excess showers right from Thiruvananthapuram through Coastal Karnataka and Mangalore to Mumbai.
Unseasonal trough The European Centre too concurs saying that an unseasonal trough would form over the Arabian Sea along and off the West Coast during this period.
If this were to be the case, it would lead to a reduction in the rainfall over Tamil Nadu coast.
Meanwhile, the unseasonal trough is forecast to develop around a feeble ‘low’ developing over the South-East Arabian Sea and Lakshadweep over the next two days.
The ‘low’ in turn takes birth out of a remnant circulation from the erstwhile ‘low’ that brought heavy to very heavy to extremely heavy rainfall to Tamil Nadu, Puducherry and Coastal Andhra Pradesh (and now lying weakened over West-Central Bay of Bengal).
India Met projections show the trough holding out until November 25 during when monsoon conditions are forecast to be normal over Sri Lanka and parts of South-East Tamil Nadu.