“Quantitatively, seasonal rainfall across the country is likely to be 92 per cent of the long-term average (LPA) with a model error of +/- 5 per cent,” IMD chief Mrutyunjay Mohapatra said while releasing the first phase of the long-term monsoon forecast.
Based on data from 1971-2020, the national seasonal precipitation LPA is 87 cm. Rainfall between 90-95% of the LPA is considered “below normal.”IMD’s forecast shows a 31% chance of “below normal” rainfall and a 35% chance of deficient rainfall (below 90% of the LPA), clearly indicating a higher likelihood of below normal rainfall in the country.While the meteorological department will issue more specific updated forecasts for the spatial distribution of rainfall during the season (June-September) in the last week of May, its “probabilistic forecast” map released on Monday clearly shows “below normal” rainfall in the country’s “monsoon core” – a region that includes large parts of central and western India and on which agricultural production relies heavily on rainfall.This scenario is most likely to affect irrigation, drinking water, reservoir capacity and hydropower potential in arid and semi-arid areas, at a time when the country is already facing high input (diesel and fertilizer) costs for agricultural operations and overall high energy costs due to war in West Asia.Reduced rainfall has adversely affected not only the area of kharif crops (sown in summer) but also rabi crops (sown in winter) due to reduced soil moisture content and reduced water from reservoirs for irrigation, thus affecting overall food production, despite the country’s various measures over the years to make its agricultural sector drought-proof.Amid the possible development of El Niño (climate conditions associated with warming sea surfaces in the central and eastern tropical Pacific), there is a strong possibility of reduced rainfall in the second half of this year’s monsoon (August-September). However, other factors, such as the Indian Ocean Dipole (IOD), may prove to be the savior. Positive IOD leads to more rainfall. So, we expect this to offset the impact of El Niño in the second half of the monsoon season,” Mohapatra said.
Neutral IOD conditions currently exist over the Indian Ocean, and the latest climate model projections indicate that positive IOD conditions may develop towards the end of the southwest monsoon season.Snow cover in the Northern Hemisphere also affects the monsoons. The IMD explained that the extent of snow cover in the last three months (January to March) was slightly below normal. “Winter and spring snow cover extent in the Northern Hemisphere and Eurasia is inversely related to subsequent southwest monsoon seasonal rainfall,” the report said.