Monsoon may arrive early, to reach Kerala by May 31: IMD
NEW DELHI: The monsoon is likely to arrive over Kerala on May 31, a day ahead of its normal onset date of June 1, scientists at the India Meteorological Department said as part of their forecast for the annual summer rain season that is crucial for the country’s farm-dependent economy.
The southwest monsoon normally hits Kerala on June 1 and covers the rest of the country by mid-july. The last time monsoon onset was ahead of its arrival date was in 2018, when it hit Kerala on May 29.
“This year, the onset of the southwest monsoon over Kerala is likely to be on May 31st with a model error of plus or minus 4 days,” IMD said in a statement on Friday.
Earlier this week, private weather forecasting company Skymet Weather also projected an earlier onset date of May 30 with an error margin of +/-2 days.
Normally, initial monsoon rains hit south Andaman Sea and monsoon winds then advance north-westwards across the Bay of Bengal. As per IMD, the monsoon typically advances over the Andaman Sea around May 22.
This time, a depression over Lakshadweep area that is likely to intensify into a cyclonic storm and move north towards the south Gujarat coast in the next few days has strengthened wind systems over the Arabian Sea. These winds, in turn, may drive initial monsoon advance over Andaman and Nicobar Islands around May 21, a day ahead of normal schedule.
Scientists say that although this is a possibility, it does not necessarily affect monsoon onset schedule.
“The development of cyclone Tauktae will definitely strengthen cross equatorial flow and help in strengthening monsoon flows. But we cannot link the cyclone with advancement in monsoon onset date directly,” explained OP Sreejith, scientist and head, Climate Monitoring and Prediction Group (CMPG) at IMD Pune.
Past data suggests there is no association of the date of monsoon advance over Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country, IMD also said in a statement on Friday.
However, Skymet Weather said that the onset could be influenced by oceanic conditions in the Arabian Sea and Bay of Bengal, and that the “likely cyclone formation in the Arabian Sea will be consequential for advance of monsoon stream over Indian waters”.
“...tropical storm Tauktae will vacate the Indian region by May 22 following which the westerly winds and cross equatorial flow will strengthen over Arabian Sea. This also will be assisted by the MJO (Madden Julian Oscillation) entering Indian Ocean with moderate amplitude. Pre-monsoon showers will be intense and hefty over Kerala,” Skymet Weather said in a statement on Thursday.
IMD has been issuing forecasts for the date of monsoon onset over Kerala since 2005 and has developed a statistical model that accounts for an error of ± 4 days for this purpose. The model accounts for six factors to forecast monsoon’s timeline, including minimum temperatures over northwest India, pre-monsoon rainfall peak over south peninsula and tropospheric winds over southeast Indian Ocean among others.
IMD said last month that India is likely to see a normal monsoon this year, with rains expected to be around 98% of the long period average (LPA) .The LPA is the average rainfall -- 88 cm -recorded from 1961 to 2010.
IMD considers rainfall between 96% to 104% of LPA to be in the “normal” range for the country.