EL NINO MODOKI

Emerging signals indicate a partial revival of monsoon rains along the country's eastern flank and southwest peninsular coast from the weekend.

Dr Akhilesh Gupta, lead operational forecaster and Adviser to the Department of Science and Technology, attributed this to an expected change in orientation of the south-westerly flows.

PENINSULR TRACK

The southwesterly-to-westerly flows are currently oriented towards the plains of the north, but forecasts indicate they would switch back to being more trans-peninsular in track from Friday onwards.

The timing of the actual revival would depend on the behaviour of two raging storms - Morakot and Goni - in the west Pacific. They would have to significantly wind down before rains can resume over India.

In any case, Bihar and adjoining parts of east Uttar Pradesh; north Orissa and Jharkhand; and Chhattisgarh and adjoining east Madhya Pradesh are expected to benefit from the easterly push in renewed rains. Alongside, a revival of sorts would get orchestrated along the west coast as well with coastal Karnataka and Kerala receiving heavier rains, Dr Gupta said.

However, northwest and north peninsular India (including Marathwada and Vidarbha) are likely to sit out since the monsoon trough is not seen moving south or evolving well enough.

Dr Gupta also said that there is no clear signal of a low-pressure area forming in the Bay of Bengal, which would have triggered a full-blown monsoon revival.

At best, a land-based circulation is what one can expect to see during the period leading up to August 12.

AUGUST RAINS

Meanwhile, no major recovery in monsoon rainfall is seen during the rest of the season (August and September), according to Dr Swadhin Behera, lead researcher at the Tokyo-based Research Institute for Global Change.

This runs counter to India Meteorological Department's (IMD) projections for normal or even excess (101 per cent) rainfall during August.

"Apparently, it is break-monsoon condition now with hardly any rain over most parts of India," Dr Behera said while interacting with Business Line.

Dr Behera, who is team leader for Low-latitude Climate Prediction Research at the Climate Variation Predictability and Applicability Research Programme, blamed El Nino and a nascent negative Indian Ocean Dipole (IOD) event for the expected shortfall in rains.

IOD refers to warming differential in the southwest and southeast Indian Ocean, with a positive IOD (warming in the southwest Pacific) favourable for Indian monsoon and vice-versa.

EL NINO MODOKI

Dr Behera also referred to an emerging pattern, called El Nino-Modoki, in which warming of the Pacific progressively shifts from the east to the central parts (and closer to India) signalling a more direct impact on monsoon.

This is unlike the previous El Nino event of 2006, when a positive IOD helped an El Nino to get established in nearly linear progression with the latter.

The weakening of eastern Pacific warming will in turn push the warm anomalies to the central Pacific. The resultant warming of the central Pacific, or El Nino Modoki, is not favourable for India monsoon.