After forecasting normal rains in April, the India Meteorological Department’s (IMD’s) updated long range forecast holds out the prospect for more normal rainfall from the southwest monsoon between June and September. Overall precipitation is expected to be 103% of the new long period average (LPA) of 868.6 mm, up from the 99% forecast in April. Normal broadly means that rainfall over season is between 96-104% of the LPA. If this forecast proves to be accurate, India will receive normal rainfall for the fourth year in a row, which is good news for cooling down the raging food inflation. Normal rains are a good augury for higher grains production during the kharif season when crops like paddy, coarse cereals, pulses and soyabean are sown. According to the IMD, most parts of the country are likely to receive good and well distributed precipitation, with central and peninsular India likely to get 106% of LPA or above normal rainfall while the northeast and northwestern India will receive normal rainfall. Together with the probabilistic forecast for rains in June to be also normal, all of this is good news for the rain-fed agricultural regions. Over half of India’s net cultivable area of 141.4 million hectares is un-irrigated and rain-dependent. More than three-fifths of farmers cultivate crops sans irrigation.
Although this complex, dynamic system arrives with unfailing regularity, there is no telling exactly when it will set in, or for that matter, its behaviour over the season, which can defeat the best forecasts. Even if the rains are “normal”, some regions experience excess rains while others suffer from drought every year. There is already a controversy between IMD and private weather forecaster Skymet over the former’s announcement of early onset over Kerala; Skymet argued that IMD declared it prematurely. But this dissension over the onset reflects a more deep-seated disagreement over the progress of the monsoon. IMD upped its forecast as it felt that La Nina—the cooling of waters in the Pacific—which contributes to moisture availability over the subcontinent to be favourable throughout the season. But the spoilsport could be negative Indian Ocean Dipole (IOD) conditions—cooler sea surface temperatures in the western Indian Ocean relative to the warmer sea surface temperatures in the eastern Indian Ocean—which “increases the chances of suppressing monsoon bursts over the Indian subcontinent”, as per Skymet. The IOD is neutral for now although it has become more negative over the past fortnight. All climate models suggest a negative IOD in the coming months, Australia’s Bureau of Meteorology has said. Last year’s rains, too, were normal at 99% of LPA, but factors including a negative IOD beyond threshold limits caused breaks in the monsoon, and poor rains in June and August.
The biggest risk to IMD’s forecasts, however, is climate change which has contributed to the increasing waywardness and unpredictability of the southwest monsoon. While the number of rainy days is declining, the incidence of very heavy and extremely heavy rainfall events has been rising. In recent memory, copious rains have flooded Mumbai, Bengaluru, Hyderabad and Chennai. During the 2021 monsoon, there were 1,636 very heavy and 273 extremely heavy rainfall events in the country. The dangerous implications of these trends for the population can be minimised by addressing climate change on a war-footing. There is also a need to reduce the economy’s monsoon-dependence by building more irrigation facilities.