Guwahati, July 30: The India Meteorological Department (IMD) has forecast a fresh spell of heavy to very heavy rainfall across Assam and several northeastern states over the next three to four days, raising concerns over flooding, flash floods, waterlogging and landslides in vulnerable areas, an official said on Thursday. According to the IMD, widespread rainfall accompanied by thunderstorms is likely between July 30 and August 1 across parts of Assam, Arunachal Pradesh and Nagaland. Similar alerts have also been sounded for Mon, Mokokchung and Wokha districts of Nagaland, where heavy rainfall is likely to generate significant runoff that may affect the adjoining Assam districts of Charaideo, Sivasagar, Jorhat and Golaghat. The weather office has also predicted heavy rainfall over several districts of Arunachal Pradesh, including East Siang, Lohit, Namsai, Longding, Papumpare, Lower Subansiri and Lower Dibang Valley. Runoff from these areas could impact Tinsukia, Dhemaji and Lakhimpur districts in Assam.