Chennai, Sep 27 : The Indian Meteorological Department (IMD) has predicted rains and thunderstorms in some parts of North Tamil Nadu and in Chennai and its suburbs. Rains will continue in Chennai and its suburbs till Friday evening, the IMD said in a statement. In the next 48 hours, the weather man has predicted thunderstorms with lightning and moderate rains over some areas of Chennai and its suburbs. The rainfall, according to IMD, is due to a cyclonic circulation in the lower part of the upper atmosphere over Tamil Nadu. P. Senthamaraikannan, Director, Regional Weather Forecasting Centre, IMD said that there will be rains for the next three to four days and this was mainly due to the cyclonic circulation over the Bay of Bengal along the Andra Pradesh coast. He said that the rains would be moderate in Chennai and suburbs and heavy rainfall is expected over some parts of North Tamil Nadu. The northeast monsoon which is the main source of water for Tamil Nadu is expected to hit the state by October 20 but weather experts said that the state will get rains by the first week of October ahead of the monsoon. With Tamil Nadu receiving quality rains during the past few months, water in almost all the reservoirs in the state is near full. /IANS