Chennai, May 21 : The Regional Meteorological Centre (RMC) on Sunday predicted light to heavy rainfall in many regions of Tamil Nadu and some parts of Puducherry. The RMC in a statement said that heavy rains are expected in The Nilgiris, Coimbatore, Theni, Dindigul, Tiruppur, Tenkasi, Dharmapuri, Krishnagiri, Tiruppatur,Erode, Salem, Namakkal and Karur districts of the state. The weatherman also issued a thunderstorm warning in these areas. In Chennai, sky is likely to be partly cloudy and a thunderstorm with light to moderate rain is likely to occur in some regions of the city. The RMC in the statement said that a trough from North Interior Karnataka to South Tamil Nadu now runs from Vidharba to South Tamil Nadu around Marathwada and interior Karnataka. Light to heavy rains are likely to occur over Tamil Nadu, Puducherry and Karaikkal areas. /IANS