Bengaluru: The Southwest Monsoons are expected to reach the South Kerala region on June 4, give or take a variation of 3 to 4 days. It will then advance into Karnataka about 7 days later and cover the coastal region by June 10. This arrival timing aligns with the normal Monsoon calendar.
The Indian Meteorological Department (IMD) provides insights into the progress of the Southwest Monsoon across the Indian mainland. The monsoon onset over Kerala serves as a crucial indicator, marking the transition from a hot and dry season to the rainy season.
As the monsoon progresses Northward, it brings relief from scorching summer temperatures. Typically, the Southwest Monsoon sets in over Kerala around June 1, with a standard deviation of approximately 7 days.
Since 2005, the IMD has been issuing operational forecasts for the Monsoon onset date over Kerala. They utilise a state-of-the-art statistical model, which exhibits a model error of ±4 days.
The model incorporates six predictors, including minimum temperatures over Northwest India, pre-monsoon rainfall peak over the South Peninsula, outgoing longwave radiation (OLR) over the South China Sea, lower tropospheric zonal wind over the Southeast Indian Ocean, mean sea level pressure over the subtropical NW Pacific Ocean, and upper tropospheric zonal wind over the East Indian Ocean.
Except for 2015, IMD’s operational forecasts of the Monsoon onset date over Kerala during the past 18 years (2005-2022) have been proven correct. Verification of the forecasts for the recent five years (2018-2022) has also shown accuracy.
This year, the Southwest Monsoon onset over Kerala is anticipated to be slightly delayed compared to the normal onset date. The expected onset date is June 4, with a model error of ±4 days. In the previous years, the actual onset dates were May 29th in 2018 and 2019, June 6 in 2020, June 1 in 2021, and June 3 in 2022.