Prolonged period of below-normal rain is due to change this year: D S Pai

Interview with Deputy director-general, climatology, IMD

The India Meteorological Department's (IMD's) first monsoon forecast for this year would have gladdened many a heart with the hope of plentiful rain, after two drought years. D S Pai, deputy director-general, climatology, IMD, in an interview with Sanjeeb Mukherjee said the rains this year could turn over a 30-year-long period of below-normal rain in India. Edited excerpts:

In your presentation on the long range forecast for 2016, you spoke of the 30-year-long epoch of below-normal rain, which could change this year. Does it mean that from 2016 onwards we would see more number of normal rain years than below-normal ones?

If you take 30-year averages of rain, you will see there are three epochs for the summer-monsoon rain. The first was in the early 20th century - of below-normal rain. A 30- or 40-year stretch of normal rain, which lasted till the 1980s, followed. Another followed, of below-normal rain, which is due to change in the next three or four years.

Whether or not 2016 will the year of the change, we don't know. The prolonged period of below-normal rain is due to turn. Our forecasts, too, are reflecting this.

When was the last time IMD gave an "above normal" rain forecast, which it has done for 2016?

The last time IMD gave an "above normal" forecast was 1999, which was 108 per cent of the Long Period Average, or LPA. Before that, it was 1988, which was 113.3 of the LPA - it was very close to the actual rainfall.

An "above normal" rainfall also raises the question of distribution.

We haven't come out with a region-wise forecast for 2016. But, if you look at good monsoon years, the trough which extends from Gujarat, Rajasthan, through Maharashtra, Madhya Pradesh and up to the Bay of Bengal gets good rain. If the mainland gets good rain, much of the problem is solved.

Is there any possibility of this forecast getting dramatically altered in the second stage update, in June?

It all depends upon how the situation pans out in April and May. But one thing is sure: we don't expect El Niño (a climate cycle in the Pacific Ocean which creates warm water pools near Indonesia and the Philippines, affecting the southwest monsoon in India) to recover. So there might not be a big change in the June update.

The forecast has sparked fears of floods and excess rain. How severe is this threat?

If "above normal" days extend abnormally long, floods might happen in some parts, but that can't be predicted now. Also, most of the rivers, canals and water bodies have almost dried up in the monsoon trough area. Only after these fill up will there be a threat of flood. The land, too, is parched, and it needs to absorb water as well.