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Insights into Editorial: IMD’s first long-range monsoon forecast to mark El Nino impact

Insights into Editorial: IMD’s first long-range monsoon forecast to mark El Nino impact


The India Meteorological Department (IMD) issued its first long-range forecast for the south-west monsoon.

while releasing its monsoon forecast, the India Meteorological Department (IMD) expressed the projected rainfall in terms of Long Period Average (LPA), saying that it was expected to be 96% of LPA.

The LPA of the monsoon season over the country is 89 cm, calculated for the period 1951-2000.

This is the average rainfall recorded during the months from June to September, calculated during the 50-year period, and is kept as a benchmark while forecasting the quantitative rainfall for the monsoon season every year.


Monsoon Impact on Agriculture:

A normal monsoon has a positive impact on the overall economy through inter-sectoral relations between agriculture and other sectors, both from the demand and supply side.

The rains are critical because nearly half of all Indians depend on a farm-based income and 60% of the country’s net-sown area does not have any form of irrigation.

Millions of farmers wait for the rains to begin summer (or monsoon) sowing of major crops, such as rice, sugar, cotton, coarse cereals and oilseeds.

Half of India’s farm output comes from summer crops dependent on these rains. Food prices have a 30% weightage in India’s consumer price index.

Robust summer rains, which account for 70% of India’s total annual rainfall, spur rural spending on most items and increase demand in other sectors of the economy.

Rural sales, for instance, account for about 48% of all motorcycles and 44% of television sets sold annually if the monsoon is normal, according to consumer sales data from the Citibank Research.

Patchy rains tend to stoke food inflation. “If the rains are well distributed, this bodes well for the general economy as well as food prices”. High food prices do not just cloud growth but also pose a political risk.

For good farm output, the rains have to be not just normal but also evenly spread across states. The monsoon also replenishes 81 nationally-monitored water reservoirs critical for drinking, power and irrigation.


Skymet Predictions on Weather:

Skymet was the first private sector entity to provide weather forecasts and weather graphics to the Indian media in 2003.

The key culprit is El Nino, the warming of the Central Pacific Ocean, that is frequently associated with drying monsoon rains.

The private weather forecaster Skymet said, it expects the coming monsoon rains to be below normal and about 7% short of the 89cm, the country usually gets from June to September as LPA.

July, the key month for agriculture is expected to be nearly 9% short. There is a higher probability that it would be below normal in June and July, it added.


IMD maintains five rainfall distribution categories on an all-India scale. These are:

IMD forecasts the category of rainfall, be it for country, region or month, the forecast is based on these standardised figures calculated for a period of 50 years.

As per the outputs obtained from the weather models, the rainfall is categorised as normal, below normal, or above normal.

  • Normal or Near Normal: When per cent departure of actual rainfall is +/-10% of LPA, that is, between 96-104% of LPA.


  • Below normal: When departure of actual rainfall is less than 10% of LPA, that is 90-96% of LPA


  • Above normal: When actual rainfall is 104-110% of LPA


  • Deficient: When departure of actual rainfall is less than 90% of LPA
  • Excess: When departure of actual rainfall is more

IMD maintains an independent LPA for every homogenous region of the country. They range from 71.6 cm to 143.83 cm.

The region-wise LPA figures are:

  • 83 cm for East and Northeast India
  • 55 cm for Central India
  • 61 cm for South Peninsular India
  • 50 for Northwest India

It puts the average of all-India figure to 88.75 cm.

The monthly LPA figures for the season are:

  • 36 cm for June
  • 92 cm for July
  • 13 cm for August
  • 34 cm for September.


How accurate are weather forecasters?

IMD’s forecast for 2019 directly challenges the prediction of India’s only private sector weather forecaster, Skymet, which is slightly more pessimistic with a forecast of 93%.

Both the IMD and Skymet have hit the bull’s eye an equal number of times in the last six years. IMD was off the mark in 2014, 2015 (which turned out to be drought years) and 2018, which narrowly escaped a drought.

2018 was the second below-normal monsoon year in a row. However, rains were better distributed than in 2017, with north India, for once, getting satisfactory rainfall.

Twelve regions saw deficits. Kerala, however, saw excess rainfall which led to devastating floods.

IMD said El Nino conditions are prevailing over the equator, but expects the same to weaken throughout the monsoon season, which lasts between June and September.

This will lead to the possibility of a normal monsoon. These rains are a crucial source of water supply for agriculture. Nearly 75 percent of India’s annual rainfall occurs during these four months.



The south-west monsoon, which makes its onset over India around May-end, is critical for its over 100-million farmer families.

The four-month rainy season contributes more than 70% of India’s annual showers.

The forecast will be closely watched as the IMD will also highlight the global impact of El Nino, and its effect on this year’s monsoons in India. The phenomenon is associated with below normal monsoon rains and droughts.

After facing droughts in 2014 and 2015, primarily because of the effects of El Nino, the monsoon rains improved in 2016 with India receiving normal rainfall in the four months between June and September.

In 2017, rainfall was near-normal, but the following year it dropped to 91% of the long period average (LPA).

The stakes are high this year as large parts of India, including Jharkhand, Maharashtra, Telangana and Andhra Pradesh, are witnessing farm distress.

Ultimately, India’s economic output will achieve stability only if it is able to escape the vagaries of the monsoon. That cannot happen without improvements in prediction and mitigation.