'Weather forecasts change with the change in conditions'

Q&A: Ajit Tyagi

The rains this kharif season has played truant and the monsoons so far have recorded a 27 per cent rainfall deficit. At least 246 districts of the country have declared a drought. The Indian Meteorological Department (IMD), the main agency that forecasts weather, has been facing strong criticism for failing to spot the problem early. IMD Director General Ajit Tyagi, spoke to Ajay Modi about what went wrong this year.

IMD's initial prediction was that the southwest monsoon this year will be 96 per cent of the long period average. Then there were two consecutive downward revisions. What went wrong?
Weather predictions are based on the latest input available. It changes with the change in conditions. This year right from the beginning there were indications (from global factors) that monsoon will be below normal and this is what we had predicted in April. By June, however, the El Nino phenomenon surfaced and we had to revise it to 93 per cent. In the same month, the Aila storm in the Bay of Bengal delayed the advance of monsoon into central India by two or three weeks. So we had to further revise our forecast downwards.

What is the model that IMD follows while making predictions? Is there any other model available?
We currently follow a statistical model. This year the statistical model has done better than the dynamical model, which is the other main model available. All dynamical models were predicting a normal to above normal rains. However, the statistical model predicted a below-normal monsoon. But I believe that the future lies with the dynamical model.

Do you think the deficient rains in during the monsoon can affect the Rabi crop, for which sowing will begin from November onwards?
If rainfall is deficient, it will lead to lower moisture content in soil and can affect crop productivity. We have to watch the rains in September which will be crucial. We are coming close to normal though a huge deficit will remain. Winter rain as such has no correlation with the summer rains.

There are talks about the Madden Julian Oscillation (MJO) and that it could revive the monsoon. Is this factor real?
The MJO is a part of intra-seasonal variation. Depending on its activity, it has the potential to impact the monsoon in a favourable manner. The deficit in summer rains, which is now 27 per cent, could come down 3 to 5 per cent if this happens. There is a view that monsoon predictions should be made for smaller regions and for smaller periods. Is the IMD working towards this?
Yes. We can currently make forecasts up to the district level. From next year onwards, all regional meteorological centres plan to (adopt) high resolution forecast models so that even village-level predictions can be made.

Is the IMD expanding its facilities or acquiring latest equipment?
We are in the process of setting up 550 automated weather stations across the country. A high power computing system is being installed at the New Delhi office. All these will help improve predictions.