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Japanese forecaster sees above-normal S-W monsoon extending into N-E monsoon

Vinson Kurian Thiruvananthapuran | Updated on April 16, 2020

Weather forecast

Monsoon may arrive over Kerala slightly earlier this year

The Application Laboratory of Japanese national forecaster Jamstec has extended the wetter-than-normal rainfall outlook for the South-West monsoon in India to the North-East monsoon as well.

Most parts of South-East Asia, the Philippines and Sri Lanka will also experience a wetter-than-normal condition during the summer monsoon. The same forecast is now being extended into the autumn for India (right until December), most parts of South-East Asia, the Philippines and Indonesia.

Warmer than normal weather

In contrast, the central parts of the US, Mexico, most parts of the South American continent, southern Africa, southern parts of West Africa, and some parts of China will experience a drier-than-normal condition during the summer, the agency said in its April-based forecast.

On a seasonal scale, the Sintex-F model predicts that most parts of the globe will experience a warmer-than-normal condition in the summer and autumn. This is based on observation of a mixture El Nino Modoki (warming in the Central Pacific accompanied by cooling in the East and West) and a canonical El Nino (warming mainly in the East Pacific).

La Nina outlook in the Pacific

The Sintex-F model of the Application Laboratory predicts that the tropical Pacific will return to a neutral state (neither El Nino or La Nina) from summer. It may be recalled a number of global models are predicting a monsoon-friendly La Nina to evolve in the Pacific (warming of the West Pacific and cooling in the East).

The India Meteorological Department (IMD), too, had hinted at this while projecting a normal monsoon (96-104 per cent of the LPA) in its forecast made available on Wednesday. As for the Indian Ocean Dipole (IOD), a strong positive phase (warming in the West of the ocean relative the East) which had catapulted the 2019 monsoon to 110 per cent of LPA, the Japanese forecaster observed that the entire ocean basin is currently warmer than normal.

Slender positive IOD chance

The Sintex-F predicts that the present state will persist through the latter half of this year. However, there is a large uncertainty in the prediction with 30 per cent of the ensemble members actually predicting a positive IOD event. Naturally, there are a few others which predict a negative phase, warming up the East of the basin.

The Weather Company, an IBM Business, a leading US-based private forecaster, has already projected a surplus monsoon for India with a rainfall of 105 per cent of the normal, riding mainly on the back of a likely La Nina in the Equatorial East Pacific.

It favours comparably heavier rain to Central, West and South India, especially entire West Coast, while projecting relatively drier climes for most parts of North-West India, parts of East India and North-East India. It said the monsoon may arrive over Kerala slightly earlier (around May 31 instead of the normal June 1) this year.

Published on April 16, 2020

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