Signaling further calamity due to the extreme weather authorities yesterday issued critical flood warnings for six major river basins and landslides warnings for a number of areas in 13 districts. The Irrigation Department issued critical red flood warnings for Kelani River Basin, Manik River Basin, Kalu River Basin, Yan Oya Basin, Kumbukkan Oya Basin, Aththanagalu Oya Basin and Kelani River Basin.