THIRUVANANTHAPURAM: The Indian Meteorological Department (IMD) has forecasted heavy rains in central-south districts of the state for the next three days. According to the IMD, these districts will receive heavy rain as the cyclonic circulation in the Bay of Bengal and south-westerly winds have strengthened. Northern districts will also receive isolated rain. A yellow alert has been issued in Kollam, Pathanamthitta, Idukki and Malappuram districts on Saturday due to rain. Fishermen have been warned not to venture into the sea till Monday as strong winds and bad weather are likely to occur along the Kerala coast.