North-East monsoon for TN, Pondy deficit by 24 percent

Both territories received only 34 cm rainfall during the season, Director of Area Cyclone Warning Centre S Balachandran said Monday.

The only district that received 11 per cent surplus rain is Tirunelveli, he said.

Dharmapuri, Krishnagiri, Chennai and Karur received rainfall 50 per cent less than normal. Fifteen districts received between one to 19 per cent deficit rainfall, he said.

Last year, there was a rainfall deficit of nine per cent for Tamil Nadu. It was 62 per cent in 2016,  the official said.

He attributed factors such as El Nino being delayed, the Indian Ocean Dipole (IOD) declining in strength during the season (October-December) and movement of cyclones, Titli, Luban and Pethai, distancing from Tamil Nadu coast, for contributing to the rainfall deficit.

El-Nino is associated with the heating of the Pacific waters and impacts the Indian monsoon, while the IOD is associated with the heating of the Indian Ocean waters.

The India Meteorological Department had said in October that the northeast monsoon, which brings a significant amount of rainfall to parts of India's southern peninsula, is "most likely to be normal."

Also called as 'retreating monsoon', north east monsoon accounts for about 48 per cent of the annual rainfall for Tamil Nadu.

Coastal districts of the state get nearly 60 per cent of the annual rainfall and the interior districts about 40-50 per cent.