Met Office predicts India Raining

With the IMD’s forecast, India joins the chorus of other Asian countries in predicting a normal monsoon. Said IMD director general S K Srivastava: ‘‘The global models have predicted neutral El Nino conditions. We are comfortable with the situation.’’

The monsoon season begins in June and the IMD has not yet predicted its onset date on the Kerala coast. It has preferred to make this prediction by May 15. This is the time the monsoon system enters the South Andaman Seas.

In the last week of June, the IMD will release its final forecast for the season and predict rainfall in July in the country’s four meteorological regions.

This year, the IMD has created a new fourth meteorological region. The earlier meteorological region, Peninsular India, has been subdivided into two. One consists of Kerala, Tamil Nadu, Pondicherry and South Andhra Pradesh. The other regions of Peninsular India consisting of Gujarat, Maharashtra, Dadra & Nagar Haveli, Madhya Pradesh and Chhattisgarh have been clubbed separately into a meteorological region. “The other two existing meteorological regions, namely north India and eastern India remain the same, ’’ said Srivastava.

He said the success of the new operational forecast models devised in 2003 were peer-reviewed and the results published in the February edition of Current Science.

Srivastava said that as per the ‘‘8-parameter power regression model,’’ the entire country will experience 100 per cent normal rains in the 4-month monsoon period, subject to a model error of +/-5 per cent.

The normal average cumulative rainfall index over the country in the 4-month monsoon season is estimated at 88 cm. If there is no model error, then the country will experience 88-cm rains.

Justifying the results of the forecast, Srivastava said: ‘‘We found 92 per cent chances of rains at 100 per cent of the long period average (LPA) of 88 cm, 4 per cent chances each of of rains below 90 per cent of LPA and rains above 110 per cent of LPA. Hence we can predict with confidence that the country will experience 100 per cent normal rains.’’

According to another 8-parameter probabilistic model of the IMD, there is a 58 per cent probality of near normal rainfall (between 92% to 102% of LPA), 4 per cent probability of deficient rainfall (less than 90% of LPA), 16 per cent probability of below normal rainfall (between 90% to 97% of LPA), 18 per cent probality of above normal rainfall (between 103% to 110% of LPA) and 4 per cent probability of excess rainfall (more than 110% of LPA).

In other words, the probabilistic model forecasts greater possibilities for a normal monsoon. The IMD has also made it clear that the current spate of rising temperatures will not come in the way of a normal monsoon. Deputy Director General S K Subramanian said that this phenomena will last only for the next two weeks. This situation is due to lack of regular western disturbances which usually bring in cool winds from Afghanistan.