The India Met Department (IMD) on Monday predicted another year of well-distributed monsoon rainfall during the crucial June-September period this year, discounting the threat of any major disruption by the El Nino factor.

“Things have changed quite a bit from February, March to April. All available model predictions from across the world suggest that the weak El Nino will lose further intensity,” said KJ Ramesh, Director-General, IMD.

Speaking to BusinessLine , he cited predictions from the Australian Bureau of Meteorology, the National Oceanic and Atmospheric Administration of the US and the European Centre for Medium-Range Weather Forecasts.

They are of the consensus view that the sea-surface temperature anomaly in Equatorial Pacific will weaken as the monsoon season establishes from June to July.

IOD booster for monsoon

“The anomaly will fade out later, leading to ‘neutral’ (neither El Nino or La Nina). And everybody seems to rule out a strong El Nino rearing its head during the season. So, this is a big message,” Ramesh said.

The IMD had predicted the same in its April 1 hot weather season prediction also. IMD had intentionally put that line into the statement, said Ramesh, for whom this is the last monsoon forecast as the D-G.

“Not just this. Almost all models are suggesting a positive phase of the Indian Ocean Dipole (IOD) to evolve as the monsoon settles. This is another potential booster promising a good monsoon.”

The IOD mimics the Pacific's El Nino-La Nina in terms of see-sawing sea-surface temperatures in the Indian Ocean. When the West Indian Ocean warms up relative to the East, it is called a positive IOD.

A positive IOD supports the concurrent Indian monsoon, while the negative phase (when the East warms up more than the West), it acts as drag on the monsoon.

The IMD forecast is based on April initial conditions, in which data at a certain time is calculated and observed before integrating the equations of motion over time to produce a forecast.

High rainfall seen

Two ways to make a forecast more accurate are to increase the accuracy of the initial guess of the state of the atmosphere, and to improve the way this information is used to produce the forecast.

According to Ramesh, only half of the work is done. Even that shows very high rainfall activity, much higher than what was indicated by the February level initial conditions. “If you take the European Centre outlook based on April initial conditions, there is no negative anomaly for rainfall for June-July-Aug, July-August-September, August-September-October,” Ramesh said. “This practically covers the entire monsoon season. That's why we said it is going to be a normal monsoon, and is going to be pretty good for agriculture and kharif sowing operations.”

Last year, all-India rainfall figure went down to 91 per cent, but if one leaves the North-East, the rainfall distribution was excellent. Reservoir levels were very good at above 10-year averages.

The sowing acreage was very good and so were yields. Ultimately, good production was also recorded. So, all-India rainfall quantum does not decide, it is its distribution that does.

This is precisely the reason despite the 91 per cent overall rainfall, the country did not suffer stress in terms of crops or yields. This year, there's a problem of drinking water, only to be expected during this time of the year.

Good spread

This year also distribution is going to be pretty good, says a confident Ramesh. As much has been mentioned in Monday’s long-range forecast bulletin.

Asked if the North-East can look for some relief this hear, Ramesh said rainfall in that region is on the decrease for almost 10 years now. There’s some ‘sort of (climate) shift’ happening there. But that should not be a cause for concern because the normal itself is very high at 180 cm to 200 cm. Even if it is less by 20 per cent, it is not bad. Any shortage, though, gets amplified against the high normal.

As for rumoured predictions of a late start to the monsoon, Ramesh said it is too early to talk about it. “In my view, monsoon establishment starts with land-ocean heating contrast.”

Heating has started quite early this year and the contrast is building up earlier than expected. Above normal temperature anomaly has been predicted for entire country from April to June.

“Given this, there should not be any concern over the establishment of the monsoon circulation itself. That's my own assessment.

“Ground level things have to form on their own and take time. What we have discussed till now are are the initial indications. They are very rightly positioned at this point of time.”

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