Pune: Officials of the India Meteorological Department (IMD) have predicted that, this year, the south-west monsoon will reach Kerala two days ahead on May 29. As per IMD officials, the south-west monsoon is expected to reach Andaman and Nicobar Islands by May 23.
The officials said that in normal conditions, the south-west monsoon sets over Kerala by June 1 with a standard deviation of about seven days. The event also marks the start of the rainy season over the region after which the monsoon progresses towards the north.
IMD has been issuing operational forecasts for the date of monsoon onset over Kerala since 2005 with a model error of about four days.
Speaking on the issue, AK Srivastava, Pune Head, Climate Monitoring and Analysis Group at IMD, told Sakal Times that this year the monsoon is expected to be early by two days.
“The usual onset date of monsoon reaching Kerala is June 1, but it is expected to reach by May 29. Although the prediction model used by IMS has a model error of four days, it is observed that in last five years, IMD has correctly predicted the onset of monsoon,” said Srivastava. He also mentioned that the south-west monsoon is expected to reach central India by June 15.
“However, exact dates cannot be predicted now. Moreover, La nina conditions are neutral and are diminishing, following which, El nino conditions will be seen but for this season, they will remain neutral,” added Srivastava.
The south-west monsoon advances over the Andaman Sea by around May 20 with a standard deviation of about a week.
Officials said that by May 23, conditions are likely to become favourable for the south-west monsoon to advance into some parts of Andaman sea and the south-east Bay of Bengal.
As per the press release issued by the Met department, they have found no association between the dates of monsoon advance over the Andaman Sea either with the dates of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country.
IMD officials noted that six predictors are used in their monsoon prediction model namely minimum temperatures over north-west India, pre-monsoon rainfall peak over south peninsula, outgoing longwave radiation over south China Sea, lower tropospheric zonal wind over southeast Indian ocean, upper tropospheric zonal wind over the east equatorial Indian ocean and outgoing longwave radiation (OLR) over the south-west Pacific region.
Forecast verification from 2013 to 2017
Year Actual Onset Date Forecast Onset Date
2013 June 1 June 3
2014 June 6 June 5
2015 June 5 May 30
2016 June 8 June 7
2017 May 30 May 30