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Early forecasts by leading global climate models suggest that India may possibly see below-normal rainfall during June-August.
This is the crucial phase when the south-west monsoon hits the country’s south-west coast and heads north in two branches (Arabian Sea and Bay of Bengal) along the western and eastern flanks.
El NinoThe deficiency in rainfall is being attributed to an evolving El Nino pattern in the central and east Pacific in which the ocean region away from Asia warms.
This causes evaporation and churning of waters to migrate towards the Americas leading to storm-building and initiation of low-pressure areas/depressions there. In contrast, the West Pacific lying closer to Indian subcontinent cools, inhibiting the process of evaporation and formation of these weather systems.
El Nino has been associated with droughts in the past, latest in 2009, but without a direct cause-effect relationship. Some El Nino years have seen normal or even surplus monsoon.
Forecast for this yearLast year saw the reverse (called La Nina) in which a hyper-active West Pacific saw weather systems march in a sustained procession India to deliver surplus rainfall over India during monsoon.
Early forecasts for 2014 monsoon by leading weather models are as follows:
European Centre for Medium-Range Weather Forecasts: May-June-July will possibly see deficient rain over parts of north-west India, especially Rajasthan and Konkan.
Outlook for the rest of the country is largely climatological, which means could vary from near-normal to below normal.
June-July-August is likely to witness below normal rain, except east-central India (Vidarbha, East Madhya Pradesh and Odisha).
Asia-Pacific Climate Centre, Busan, South Korea: East and north-east India may witness below-normal thundershower activity during March-April-May.
Below-normal rain for the central and east peninsula (Karnataka, Andhra Pradesh, Vidarbha, Jharkhand, Chhattisgarh, and east Madhya Pradesh) during the same period.
Core monsoon phase of June-July-August will likely witness below-normal rain over almost entire landmass except parts of Rajasthan, Haryana and Delhi.
Regional Institute for Global Change under Jamstec, Japan national weather agency: Below-normal rain for almost entire peninsular India during March-April-May.
Below-normal rain during June-July-August for the entire country except parts of east India and north-east.
A few of the models suggested that an extended winter may also have its impact on the monsoon flows that depend on differential heating of the sea and the land.
The difference between sea and land temperatures set up a pressure gradient which the southwest monsoon rides to enter land (air moves from areas of high pressure to those of lower pressure).
Extended winter may cause a delay in warming of the land surface and retard this process, according to experts.
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