by Elton Gomes
In its recently-concluded monsoon, India recorded a below normal rainfall to the tune of 91 percent of the long period average (LPA), according to a report by private weather forecaster SkyMet Weather. It has been confirmed that the four-month-long southwest monsoon season has officially ended on October 1.
According to SkyMets report, the cumulative rainfall across India for the overall season between June 1 and September 30 was recorded at 804 millimetre (mm) against the normal rains of 887.5 mm. Overall rainfall was 84 mm lesser than normal. The report also said that rainfall in 2018 displayed a deficit in all four months.
How does the IMD define average rainfall
The Indian Meteorological Department (IMD) defines average, or normal, rainfall as between 96 percent and 104 percent of a 50-year average of 89 cm for the four-month monsoon.The IMD adopted a dynamic model, which was based on a U.S. model specially modified for Indian conditions, for the first time in 2017 to improve the accuracy of its forecasts.
Despite low rainfall overall, India witnessed erratic distribution of rainfall, with some parts experiencing extreme rainfall and flash floods that claimed lives of hundreds of people and damaged crops and property.
What was predicted
D. Sivananda Pai, IMDs lead monsoon forecaster, said, It was the high monsoon shortfall in September that led to the inaccuracy. We were expecting 90-91% rainfall in September after taking into consideration an evolving El Nino. But high convection activity in northwest Pacific during the month drew moisture away from our region, the Times of India reported.
September concluded with a shortfall of over 23% and it was the driest monsoon for the month since 2015. In its forecasts in April and May, the IMD had said the monsoon was likely to be 97% of LPA. In an update for the second half of the season (August-September) released in early August, IMD had forecast 95% rainfall for the two months.
However, the actual rainfall during the period was somewhere close to 87%. Additionally, private forecaster Skymet, which had initially predicted 100% monsoon rainfall this year, corrected its numbers midway into the season. In an update released on August 1, Skymet downgraded the monsoon to below normal at 92% of the long period average a forecast that was really close to the actual figure.
Skymet had, however, forecast poor rainfall in August (88%) and a slightly better performance in September (93%). But the opposite turned out to be true, as rainfall in August was slightly less than 93% of LPA, as reported by the Times of India.
Why was India’s rainfall below average
Indias rainfall was below average largely due to a lack of precipitation in the rice and maize-growing states of Bihar and Jharkhand and in the cotton-growing state of Gujarat. Major farm-dependent states, such as the oilseed and pulses-growing central state of Madhya Pradesh and the northern, rice-growing state of Uttar Pradesh received rainfall that was lower than the long-term average. The drop in rainfall could lead to a rise in food prices and stoke inflation in India, which is already battling high fuel prices.
Elton Gomes is a staff writer at Qrius