Tamil Nadu will receive more than 32 per cent of its total annual rainfall from the South West Monsoon (SWM) (between June and September 2015) and this is despite lying in the rain shadow area to SWM, say researchers at the Agro Climate Research Centre, Tamil Nadu Agricultural University.
Findings from a seasonal rainfall forecast for the different districts of Tamil Nadu reveal that districts such as Dharmapuri, Krishnagiri, Salem, Nilgiris and Kanyakumari will be dominated by the SWM this year.
However, from the average taken over a long period, it is observed that other districts in Western zone, North Eastern zone and Cauvery delta would receive 100 to 150 mm of rainfall during SWM.
Normal rainfall (+/- 10 per cent of the long term mean seasonal rainfall) is predicted in Ariyalur, Chennai, Cuddalore, Dharmapuri, Dindugal, Kancheepuram, Kanyakumari, Krishnagiri, Namakkal, Ooty, Perambalur, Pudukottai, Salem, Thanjavur, Thiruvallur, Thiruvannamalai, Trichy, Vellore and Villupuram.
Districts such as Coimbatore, Erode, Karur, Theni, Tirupur and Madurai can expect near normal rainfall, while some of the Southern districts such as Ramanathapuram, Sivagangai, Tirunelveli, Thiruvarur, Tuticorin and Virudhunagar will receive below normal rainfall, the researchers say.
Researchers said that the forecast is based on the Southern Oscillation Index of summer season and sea surface temperature values of Pacific and Indian Oceans using Australian Rainman International V.4.2 software. The rainfall probability is said to be 60 per cent.