AMN / NEW DELHI
Good news to farmers who mainly depend on monsoon, the country is likely to receive normal monsoon rainfall this year.
Briefing media here on Southwest Monsoon season rainfall forecast, Secretary, Ministry of Earth Sciences Dr M Rajeevan said, monsoon seasonal rainfall from June to September is likely to be 96 per cent of the long period average, LPA.
Monsoon rainfall this year is forecast to be 96% of the Long Period Average (or 89 cm, which is a 50 year average of India’s monsoon rains).
Strictly speaking, a 96% forecast is, in the IMD lexicon, “near normal.” This is just shy of ‘below normal’ (90%-96% of LPA) rain.
He said that over a long period average (LPA), they expect 96% rainfall of 89 cm. LPA is the average of rainfall between 1951 and 2000, which is 89 cm. Anything between 90-95 per cent of LPA falls under the “below normal” category.
According to IMD’s monsoon forecast, rainfall will be well distributed. The south-west monsoon makes its onset over India around May-end and is critical for the agriculture sector. The four-month rainy season contributes more than 70% of India’s annual showers.
According to the latest global forecasts, weak El Nino conditions have developed over equatorial Pacific Ocean and they are likely to persist this summer. However, IMD officials have maintained that these conditions would weaken after summer.
If El Nino retains strength and impacts monsoon rains in June and July, the first two months of the season, it could lead to delay in sowing of rain-fed kharif crops affecting overall crop production.
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.
Nair said IMD doesn’t expect any adverse impact on the monsoons from El Nino.
In 2017, rainfall was near-normal, but the following year it dropped to 91% of the long period average (LPA).
Today’s IMD forecast will be followed by a second long-range forecast in May, containing predictions for each of the meteorological sub-divisions.
However, Madhavan Rajeevan, Secretary, Ministry of Earth Sciences (to whom the IMD reports), at a press conference emphasised that this year’s forecast was for “normal” rains. “For all practical purposes, we expect normal rains,” he added.
This is a more optimistic assessment from the one by private weather forecasting agency, Skymet, which earlier this month, warned of ‘below normal’ rains June-September.
The IMD’s optimism stems from global climate models projecting a ‘weakening El Nino.’ The El Nino, a cyclic warming of the Central and Eastern Pacific region, has historically been linked to a weakening of monsoon rain.
A temperature rise greater than 1 degree C for three months at a trot, is considered a ‘strong’ El Nino (and threatening to the monsoon). A 0.5C -1C rise is called ‘weak El Nino conditions.’ Currently the El Nino is 0.9 C.
The IMD’s models in March, expect the El Nino to peak around May and then recede for the rest of the monsoon months. “Globally too, other models that track El Nino expect it to recede after June or July. So that reflects in our forecast (of a normal as opposed to below normal monsoon rains),” said Mr. Rajeevan. In any given year, the odds of ‘below normal’ rains are 17%.
This year — the IMD’s assessment says — the odds are 32% which Mr. Rajeevan admitted was “significant.” However the odds of ‘near normal’ rains this year were 39%, the IMD’s forecast notes. “It’s a matter of how you expect the El Nino to pan out…we combine our own experience with the model’s insights to make the forecast,” said K.J. Ramesh, Director-General, IMD.
The IMD issues its first monsoon forecast in April and then updates it in June with details on how the monsoon will perform in various geographical regions.