Monsoon onset over Kerala is likely to be on May 27, five days ahead of its expected onset, India Meteorological Department (IMD) said on Friday. It left a model error of ±4 days in the forecast.
Monsoon normally makes onset over Kerala on June 1. Initial monsoon rains are experienced over the south Andaman Sea and the monsoon winds then advance north-westwards across the Bay of Bengal.
“As per the normal dates of monsoon onset/progress, the southwest monsoon advances over the Andaman Sea around 22nd May. In association with enhanced cross-equatorial winds, conditions are becoming favorable for the advance of Southwest Monsoon into the 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,” the IMD said in a statement.
According to private weather forecasting company Skymet Weather, Monsoon is likely to arrive over Kerala on May 26.
In April, Skymet had also forecast that the upcoming monsoon season will be ‘normal’ to the tune of 98% (with an error margin of +/- 5%) of the long period average (LPA).
“Skymet expects the onset to be earlier than the normal date. Based on the data from 1961 to 2019, the normal date of onset over the Indian mainland is June 1. The onset of the Southwest Monsoon over Kerala is chiefly controlled by oceanic conditions, both in the Arabian Sea and Bay of Bengal. Recent cyclone Asani enabled the monsoon stream to lock in over the Bay of Bengal, earlier than normal,” Skymet said in a statement on Friday.
“Also, the remnant of this storm, as a depression over Peninsular India, has been instrumental in initiating the cross-equatorial flow. The combined influence has wiped away the anti-cyclone over the central parts of the Arabian Sea, an essential condition for ingress of monsoon surge. This will also be assisted by the MJO (Madden Julian Oscillation) entering the Indian Ocean, albeit with low amplitude. Pre-Monsoon showers will be extensive and powerful over Kerala. Skymet predicts that this year, the onset of southwest monsoon over Kerala is likely to be on 26 May 2022 with a model error of +/- 3 days,” the statement added.
MJO is a band of rain clouds that moves eastwards over the tropics and is responsible for most weather variations in the region – including the Southwest and Northeast monsoons.
“It’s been raining in the South Andaman region. We expect the monsoon to reach the South Andaman region around May 15-16. The winds are south-westerly, and cross-equatorial flow has started establishing. Over Kerala also, the pre-monsoon activity has started. The entire south peninsular region has received good rainfall because of cyclone Asani,” said Mahesh Palawat, vice president, Skymet Weather.
The Southwest monsoon normally arrives over Andaman and Nicobar Islands on May 22.
“With the timely onset, the progress of monsoon is likely to be good, which will definitely support timely sowing of rabi crop up to central India. So, it will come as a great relief to farmers,” added Palawat.
On Thursday, the IMD) had forecast that monsoon will reach South Andaman Sea by May 15. Widespread light to moderate rainfall is likely over Andaman and Nicobar Islands during the next five days and isolated heavy rain from May 14 to 16, the weather office had said.
Squally weather with wind speed reaching 40-50kmph gusting to 60kmph is also likely over South Andaman Sea on May 15 and 16, it said.
IMD’s extended range forecast, published on Indian Institute of Tropical Meteorology’s website, shows widespread rainfall over Kerala between May 20 and 26.
“Monsoon update: Good News! @Indiametdept extended range forecasts consistently suggest favourable conditions for an early monsoon onset over Kerala & its northward movement. Pl watch out @Indiametdept official forecast scheduled on 15 May for the exact date of monsoon onset,” tweeted M Rajeevan, former secretary, ministry of earth sciences on Thursday.
IMD had also forecast last month that monsoon is likely to be “normal” at 99% of long period average (LPA) with an error margin of +/-5%.
If the projections are proven right, this will be the fourth consecutive year when the monsoon has been in “normal” or “above normal” range.
In 2021, monsoon rainfall was 99% of LPA in “normal” category; in 2020, monsoon was 109% of LPA in “above normal” category; in 2019 monsoon was 110% of LPA, also in “above normal” category.
