The normal onset date for monsoon over Kerala is June 1.
Southwest monsoon, considered the lifeline of India’s agri-based economy, is likely to bring the first showers to Kerala by May 27, earlier than the normal onset date, the India Meteorological Department announced on Friday, May 13. The normal onset date for monsoon over Kerala is June 1.
This year, the onset of the southwest monsoon over Kerala is likely to be earlier than the normal date of onset. The monsoon onset over Kerala is likely to be on May 27 with a model error of four days, the IMD said.
The early arrival of the southwest monsoon comes at a time when parts of northwest India are experiencing extremely high maximum temperatures. Monsoon is likely to make an early onset over Andaman and Nicobar Islands by May 15, the weather office said.
The IMD added that the southwest monsoon normally sets in over Kerala on June 1, with a standard deviation of about seven days. The India Meteorological Department (IMD) uses an indigenously developed statistical model, with a model error of ± 4 days, to predict the onset of monsoons.
The IMD has also said that in association with enhanced cross-equatorial winds, conditions are becoming favourable for the advance of southwest monsoon into South Andaman Sea, Nicobar Islands and some parts of southeast Bay of Bengal around May 15. Past data suggest that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country.
Southwest Monsoon has a wide-ranging impact on India’s economy with agriculture, economy, trade, travel, etc decided by the rainfall quantum and timing. Former Secretary, Earth Sciences, M Rajeevan Nair had said: “Generally SouthWest Monsoon reaches Andaman & Nicobar Islands by May 19-20. This time it is at least a week in advance.”
At present, the IMD uses a criterion adopted in 2016 for declaring the onset of monsoon over Kerala, which was based on the daily rainfall of 14 stations over Kerala and the neighbouring area along with wind field and outgoing longwave radiation (OLR) over the southeast Arabian Sea. It emphasises upon the sharp increase in rainfall over Kerala along with the setting up of large-scale monsoon flow and extension of westerlies up to certain criteria.
With agency inputs