In a major relief, at least for the southern part of the country, monsoon hit the Kerala coast on Wednesday, a day later than what was earlier forecast.
The Met Department on Wednesday declared that south-west monsoon had arrived over Kerala. However with a plus or minus four days error, the Met Department claimed that it had arrived within the forecast period. Notably, the Met had predicted the onset of monsoon on June 7.
“We had maintained that the south-west monsoon would touch the Kerala coast before June 9 and after observing the strengthening of winds and rainfall activity over Kerala, Lakshadweep and coastal Tamil Nadu we declared the onset over Kerala after checking for all parameters,” IMD director general LS Rathore said, adding that the southwest monsoon had reached up to Kannur and Chennai and covered most part of Kerala and Tamil Nadu.
“The condition is favourable for its further advancement over coastal Karnataka, some more parts of south Andhra Pradesh and remaining parts of Tamil Nadu in the next 48 hours,” Rathore added.
The conditions observed by the Met department included monitoring the 14 stations of Kerala reporting widespread rainfall for the last 48 hours with more than 60 per cent of the stations reporting rainfall on June 8. The other parameters included the intensity of the westerly and west southwesterly winds over the South Arabian sea, and the outgoing long wave radiation value which basically shows the cloudiness over the region.
The onset was delayed by a week and the statistical model used by the department had declared that the monsoon onset is likely to set over Kerala on June 7, with a model error of plus or minus four days. The onset of the southwest monsoon over Kerala represents the start of the rainy season for the country.
The normal date is June 1 and the model to predict the onset uses six predictors – minimum temperatures over north-west India, pre-monsoon rainfall peak over south peninsula, outgoing long wave radiation over South China sea, lower tropospheric zonal wind over southeast Indian ocean, upper tropospheric zonal wind over east equatorial Indian ocean and outgoing long wave radiation over the south west Pacific region.