Assam, two NE states brace for below normal monsoon despite flood-hit start
The East and Northeast India regions also recorded below normal monsoon rains in the last consecutive four years.
A file image of rain on city streets. (Representational Image, PTI)
Guwahati, Jun 4: Assam may have recorded good pre-monsoon rains triggering floods within days of monsoon onset, but the outlook for the four monsoon months looks bleak, if the long range forecast of the India Meteorological Department (IMD) is to be believed.
Assam is among three north-eastern states – besides Arunachal Pradesh and Meghalaya – which are likely to have below normal rains during the season, unlike the rest of the country where prediction is for normal monsoon rainfall.
“The probabilistic category forecast of rainfall for 36 meteorological subdivisions of India indicates that most of these subdivisions are likely to receive normal to above normal rainfall during June to September 2025 except Arunachal Pradesh, Assam and Meghalaya which would experience below normal rainfall. The forecast probability is 54 per cent,” the IMD said in its second long range forecast.
The first forecast released by the IMD in April also had a similar prediction.
If the forecast comes true, it will be the fifth consecutive year when Assam-Meghalaya subdivision will experience below normal monsoon rainfall. The normal monsoon rainfall in the subdivision is 1,762.2 mm. The East and Northeast India regions also recorded below normal monsoon rains in the last consecutive four years.
Weather scientists said research is required to understand the phenomenon. “There are some studies by researchers. Some suggest it is mainly due to global factors, not much contribution of local factors. And another important thing about rainfall is the multi-decadal variability,” an IMD scientist said.
“For consecutive decades it rains less in a region (called negative epoch), then again for some decades it rains more (called positive epoch). The Northeast could be currently in the negative epoch. It was in positive epoch during 1910-1950. Then, it shifted to less rains. Currently, all-India rainfall is in positive epoch. We are getting more higher rainfall years for the country as a whole,” the scientist added.
Research scientist at the National Centre for Atmospheric Science & Department of Meteorology, University of Reading, Dr Akshay Deoras also said there is no single answer to this very important question.
“Some studies suggest that the drying pattern in recent decades is associated with the natural variability of the southwest monsoon, more specifically with its interdecadal variability that is tied to the Pacific Decadal Oscillation (a long-term see-saw in the sea surface temperature across the Northern Pacific Ocean),” Deoras said.
“Some studies again point towards an increasing tendency of monsoon low-pressure systems to penetrate deeply into India, which in a way reduces the transport of moisture (and subsequently rainfall) to Northeast India. I haven’t specifically looked at whether this hypothesis holds true in observations. Some attribute the rainfall reduction to changes in the land use type. I personally agree with the interdecadal variability aspect,” he added.