Seasonal climate updates by most models continue to predict a ‘near-normal to normal' monsoon for India, with the odd one maintaining the outlook for ‘surplus to flooding rains'.
Models also tend to agree with the outlook that the ‘monsoon-killer' El Nino may already have started breaking down in the eastern Pacific.
GAME CHANGER
The Australian Bureau of Meteorology said in its latest update that the 30-day SOI (Southern Oscillation Index) value has gone positive early this month for the first time since September of last year. Its current value of +6.2 is the highest 30-day SOI since late June 2009.
SOI is one measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (the state of the Southern Oscillation) during El Nino and alter-ego La Nina episodes.
According to the Climate Prediction Centre (CPC) of the US National Weather services, an increasing number of models are predicting below-average temperatures in the eastern Pacific in the late summer.
Some forecasts have tended to meet thresholds for a La Nina. However, it should be noted that model skill is at a minimum during this time of year. La Nina has been associated with normal India monsoon, though without cause-effect relationship.
LA NINA STRENGTH
An April update from the Tokyo-based Research Institute for Global Change (RIGC) says that the current El Nino would end soon and a ‘fairly strong La Nina' condition would develop during this summer.
But the RIGC has suggested that La Nina would not have the additional prop from a favourable Indian Ocean Dipole, which mimics El Nino-La Nina in the Indian Ocean) this time.
The RIGC has maintained its outlook for ‘more rains or even floods' for India, Indonesia, Australia and northeast Brazil during this season. Some relief could be had for southeastern China, which is witnessing severe drought conditions currently.
Meanwhile, the ongoing South Asian Climate Outlook Forum at Pune observed on Thursday that monsoon rains over south Asia will probably be near normal this season.
RIGC is also of the view that the monsoon onset and advance stage would be weak, with below normal rainfall being predicted for the southwest coast in June.
The June-July-August outlook also sees rainfall deficit in east-central India, too. But normal to above normal rainfall could be expected during September-October-November backed up by likely La Nina conditions.
Month-wise forecasts from RIGC are as follows:
May – below normal rains along the west coast and west-central India as well as parts of northwest India while it would be normal to above normal over the east and northeast;
June – below normal to deficit rains for southwest coast and southeast Arabian Sea, from where the monsoon is catapulted for a final time before makes it to the onset; and
July – rainfall surplus over peninsula, varying deficit over east and east-central India and the Mumbai-Konkan belt.
Meanwhile, India Meteorological Department (IMD) categorised Wednesday's devastating thunderstorm over Bihar and West Bengal as a tornado/squall line formation packing brute strike power.
It traced the violent weather to Nor'wester activity (westerly winds) ably supported by the unstable weather generated by a combination of explosive factors.
For instance, the heated-up surface and moisture incursion from the Bay of Bengal were brought into play within the storm-breeding ground of a trough that existed in the region.
An expert team has been deputed to the site of destruction to assess the situation and IMD expected to come out with a detailed report soon.
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