New Delhi, May 14 (IANS): Even as northwest India and Indo-Gangetic plains sizzle in a heat wave and severe heat wave, large parts of northeast India witnessed heavy to extremely heavy rainfall on Saturday with several stations, especially those across Meghalaya, recording rainfall of more than 150 mm in 24 hours.

The IMD has warned of a similar heavy to extremely heavy rainfall activity till May 18.

An east-west trough runs from Bihar to central Assam and Meghalaya across sub-Himalayan West Bengal and Sikkim at 0.9 km above mean sea level. Moisture incursion from the Bay of Bengal is likely to continue over NE India due to the strong lower-level southerly/southwesterly winds during May 14-18.

"Under the influence of the above system, widespread rainfall accompanied with thunderstorm/lightning and heavy to very heavy rainfall at isolated places is very likely over Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura and thunderstorm/lightning and heavy to very heavy rainfall with extremely heavy rainfall at isolated places over Meghalaya," said Sanjay O'Neill Shaw, senior scientist with the IMD's Guwahati Regional Meteorological Centre.

In its forecast for May 19-21, the IMD has said that fairly widespread light to moderate with isolated heavy rainfall is likely to continue over northeast India, sub-Himalayan West Bengal, and Sikkim.