IMD says that normal southwest monsoon is likely this year

by Mayank Aggarwal on 17 April 2018

• The India Meteorological Department has forecasted a normal southwest monsoon this year. It is likely to be 97 percent of the long period average (LPA) with a model error of ± 5 percent.
• The IMD also predicts a low probability of deficient rainfall.
• Experts question whether it will help the farmers.

The India Meteorological Department (IMD) has forecasted that the country is likely to experience ‘normal’ rainfall in the 2018 southwest monsoon season. The forecast spells good news for the country’s agriculture sector and is also expected to be good for the economy.

“The monsoon seasonal rainfall is likely to be 97 percent of the long period average (LPA) with a model error of ± 5 percent,” read a statement by the IMD. India’s average rainfall for the southwest monsoon for the 50-year period (1951-2000) is 890 millimetres.

The forecast also predicted “maximum probability for normal monsoon rainfall (96-104 percent of the LPA) and low probability of deficient rainfall during the season”.

File picture of monsoon clouds building along the Kerala coast. Photo by Raji Warrier.

Normal rainfall in the southwest monsoon season is important for the country as it aids farmers. This four-month season is also crucial as over 65 percent of India’s annual rainfall comes during this season.

Earlier this month, Skymet Weather, the private weather forecaster, predicted that monsoon in 2018 is likely to be normal at 100 percent with an error margin of +/-5 percent. It had ruled out any chance of drought.

The IMD issues the forecast for the southwest monsoon seasonal (June to September) rainfall for the country in two stages. The first stage forecast is issued in April and the second stage forecast is issued in June.

“Monsoon is likely to be normal at 97 percent of the long period average for the four-month period from June to September,” said the IMD’s director general K. J. Ramesh while adding the forecast means that the country is likely to have a third successive year of normal rainfall.

In 2017, the rainfall was quite close to normal at 95 percent of the LPA and in 2016 it was 97 percent of the long period average.

“Along with the updated forecast, separate forecasts for the monthly (July and August) rainfall over the country as a whole and seasonal (June-September) rainfall over the four geographical regions of India will also be issued,” the IMD emphasised. The Met Department officials, however, refused to predict any month-wise forecast for the monsoon rainfall.

The southwest monsoon brings relief after the scorching summer. Photo by Raji Warrier.

Lesser chances of deficient rain

According to the IMD’s forecast, there is a 54 percent probability of the country witnessing normal or above normal monsoon while the chances of a deficient and below normal monsoon are 44 percent only. However, there is only a small two percent chance of excess rainfall in this season.

“As the extreme sea surface temperature conditions over the Pacific and Indian oceans particularly ENSO conditions over the Pacific (El Nino or La Nina) are known to have a strong influence on the Indian summer monsoon, IMD is carefully monitoring the sea surface conditions over the Pacific and Indian oceans,” the statement said.

While the overall monsoon rainfall is normal, its distribution and intensity have been a concern area for the government.

“The government is monitoring the variability of the weather phenomena and development of abnormal weather like deficient monsoon rainfall, flood, flash flood, cyclone, rain-induced landslides, heat/cold wave, etc. on a continuous basis. Heavy rain events (more than 100 mm/day) over central India are found to have increased in the recent decades while weak and moderate rainfall events are decreasing,” Harsh Vardhan, India’s minister for earth sciences, told the Parliament earlier this month.

“Heat waves typically occur between March and June. Heat waves are more frequent over the Indo-Gangetic plains of India. There is an increase in heat wave frequency over central and northwest India,” he added.

Forecast accuracy is improving

S. Pai, senior scientist with IMD, asserted that the Met Department’s prediction accuracy has improved over the years.

“In the 1996-2006 period, the forecast was within +/-8 percent of actual values during seven years. Within these seven years, the forecast was within +/-4 percent during two years. On the other hand, during 2007-2017, the forecast was within +/-8 percent of the actual values during eight years with forecast within +/-4 percent during five years. These figures clearly indicate the improvement made in the operational forecast system in the recent 11 years period compared to earlier 11 years,” Pai explained.

Will a normal monsoon benefit the farmers?

A good monsoon will aid farmers and boost farm productivity but experts argue that despite record production, farmers are not getting the benefit.

Monsoon is the lifeline for agriculture in the country. Photo by S. Gopikrishna Warrier / Mongabay.

“A forecast of good monsoon by the IMD for the third year in a row is certainly good news. But the point is that for three years we had record production and yet farmers are dying. Agrarian distress is growing because prices crashed by an average of 15-40 percent. When will farmers have reasons to celebrate a bountiful monsoon?” said Devinder Sharma, an agriculture policy expert.

“Even if the monsoon is normal across the country the point is that the farmers are still dying.  The reason is that the country does not know how to manage surplus food,” Sharma stressed.