The India Meteorological Department (IMD) on Friday forecast heavy rainfall in parts of Bihar, and warned of low to moderate flash flood risk in 13 districts over the next 24 hours. Heavy rain is likely in West Champaran, East Champaran, Sitamarhi, Sheohar, Muzaffarpur, Gopalganj, Siwan, Saran, Vaishali, Patna, Jehanabad, Madhubani and Bhojpur districts, it said in a bulletin. These districts are at the risk of low to moderate flash floods in the next 24 hours, the Met Department said. The Disaster Management Department (DMD) has asked the administration of the districts to remain on alert, and take preventive measures in the wake of the forecast. The department has written a letter to the 13 district magistrates in this regard. Around 12 districts situated along the Ganga, including Buxar, Bhojpur, Saran, Patna, Samastipur, Begusarai, Munger and Bhagalpur, are experiencing a flood-like situation in the state, and nearly 13.5 lakh people living in low-lying areas have been affect