A day after the India Meteorological Department (IMD) announced a slightly delayed onset of the monsoon this year (June 4 as against the normal June 1), the latest seasonal forecast for the June-September period by various agencies signal mixed fortunes for the monsoon. 

The South Asian Climate Outlook Forum (SASCOF) expects the monsoon to deliver below normal rainfall over some areas in the North-West, Central and North-East of the South Asia region, while above normal rainfall is likely over the North and North-West, as well as parts of East and South-East. 

SASCOF seasonal outlook 

The outlook from the 25th session of SASCOF was released on May 5, which identified areas of below normal rainfall, including parts of North India (52 per cent probability) and Central India (40 per cent probability). Areas likely to be affected include Gujarat, Rajasthan, Punjab, Haryana, Delhi, Uttar Pradesh, West Bengal and North-East India. Areas likely to receive above-normal precipitation include East India (50 per cent probability) and South India (60 per cent probability). 

The IMD had said in its first long-range monsoon forecast in April that it expects a ‘normal’ monsoon for the fifth year on the trot. The seasonal precipitation is expected to be 96 per cent (with a model error of ± 5 per cent) of the long-period average. Spatial rainfall spread will be determined by a looming El Niño and an expected positive Indian Ocean Dipole phase. 

Global model forecasts

Some global weather models make more or less similar forecasts that range from a wider spread of the below-normal rainfall regime, to the normal or just below-normal. The Busan, South Korea-based APEC Climate Centre is the most pessimistic, signalling a near-washout during June to August, except along the West Coast, Odisha-Chhattisgarh, and Jammu & Kashmir and Ladakh. 

The Application Laboratory of the Japanese national forecaster Jamstec does not share the APEC Climate Centre’s dire predictions. It suspects rainfall would be normal over a large part of the country during the period, with spots of deficit over the foothills of the Eastern Himalayas (West Bengal and North-Eastern States) and North Interior Karnataka. 

Surplus along West Coast

The European Centre for Medium-Range Forecasts sees the probability of heavy rainfall for Kerala, coastal Karnataka, Goa, Konkan (including Mumbai) and slightly less intense rain over adjoining parts of South Gujarat during June-July-August. Among areas that would witness below-normal rainfall are Uttar Pradesh, Bihar, Central Madhya Pradesh and parts of Telangana and Rayalaseema. 

While June is the first month of the season that sees the onset and progression of the monsoon from the South-West coast and upwards, July is the rainiest month, and August, the second rainiest. In early September, the monsoon starts withdrawing from extreme West Rajasthan.

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