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IMD predicts normal rainfall, at 97% of LPA

IMD predicts normal rainfall, at 97% of LPA

As per historical data, the long-period average (LPA) rainfall - between June and September - is 89cm. In 2016, good monsoon has led to record production of oilseeds, food grains and also triggered a 4.2 per cent agriculture growth. If the average rainfall is below 90 per cent of LPA, the Monsoon is termed "deficient".

Forecast suggests maximum probability for normal rainfall and a low probability for deficient rainfall during the season.

The LPA for the season is calculated on the basis of the mean rainfall during the four-month monsoon season over a 50-year period from 1951-2010.

Quantitatively, the monsoon seasonal rainfall is likely to be 97% of the Long Period Average (LPA) with a model error of ± 5%.

IMD issues operational forecast for the southwest monsoon seasonal (June to September) rainfall for the country as a whole in two stages.




The IMD, meanwhile, said it would be able to forecast a clearer picture of the Monsoon, which normally extends from June 1 to September 30, only in June. The dynamic model has forecast a rainfall of 99 per cent plus or minus a model error of five per cent, while the statistical model forecast is 97 per cent plus or minus model error of five per cent.

If the forecast holds true, 2018 will be third successive year of normal rains.

Despite "normal" forecast, the monsoon can be affected by the El Niño conditions.

Monsoon rains, the lifeblood of the country's $2 trillion economy, are expected to be 97 percent of a long-term average, K.J. Ramesh, director general of the state-run India Meteorological Department (IMD), told a news conference.

The IMD's reasoning for the unexpected break is that it was caused by intra-seasonal variability as Pacific cyclones over Bay of Bengal pulled the monsoon currents towards them, leading to the disappearance of rains over Central and Northern India, plunging them on the brink of drought.