IMD, Skymet Weather differ on monsoon arrival

The India Meteorological Department (IMD) on Saturday reiterated the monsoon is likely to arrive in Kerala only around June 1 after private weather forecaster Skymet Weather announced it has already arrived in the state earlier than expected. It called the forecaster’s information incorrect. Skymet maintained the criteria including for the rainfall has been met.

IMD director general M Mohapatra said the criteria is yet to be met. “We have a very objective way of assessing monsoon onset and we stand by our forecast of monsoon onset around June 1. It could be June 1 or 2 depending on the parameters... Even the rainfall criteria have not been met today [Saturday].”

IMD on Thursday said the monsoon was likely to arrive in Kerala, which marks the beginning of the four-month rainy season when India receives 70% of its annual rainfall, around its normal onset date of June 1. It said there were new developing patterns that could speed up the progress of the rain system. IMD on May 15 said the onset was likely to be delayed by four days and the monsoon was expected to arrive on June 5.

The monsoon normally sets in over Kerala around June 1 and advances northwards, usually in surges, and covers the entire country around July 15.

IMD criteria specifies the onset is determined if, after May 10, 60% of 14 weather stations in Lakshadweep, Kerala and Coastal Karnataka report rainfall of 2.5 mm or more for two consecutive days, high wind speed, low outgoing longwave radiation (OLR), etc. It also specifies a wind depth parameter.

Skymet Weather’s vice president (climate and meteorology) Mahesh Palawat said they have over a hundred automatic weather stations in Kerala. “...we are seeing that the rainfall criteria has been met. The wind profile is westerly and OLR criteria have also been met. IMD may declare monsoon onset later but we announced today [Saturday] because all parameters are fulfilled.”

Union earth sciences ministry secretary M Rajeevan echoed Mohapatra. “The news about monsoon onset over Kerala in social media is not correct. Monsoon has not arrived over Kerala. Follow Indiametdept for authentic information. The greatest enemy of knowledge is not ignorance, it is illusion of knowledge—Stephen Hawking,” he tweeted.

National Weather Forecasting Centre head K Sathi Devi said it is not only rainfall, even the wind depth parameter has to be met. “The wind speed should be very high and there should be a lot of clouding. We are expecting a low-pressure area to form over the south-east Arabian Sea which will lead to all parameters being met. Currently, what we are seeing in Kerala are pre-monsoon showers.”

IMD said conditions were becoming favourable for further advance of the monsoon into some more parts of south Arabian Sea, Maldives-Comorin area, south-west and the south-east Bay of Bengal during the next 24 hours. A low-pressure area was very likely to form over south-east and adjoining east-central Arabian Sea during the next 48 hours. It is very likely to move northwestwards and concentrate into a depression over east-central and adjoining south-east the Arabian Sea during subsequent 48 hours. Under its influence, conditions are likely to become favourable for onset of the monsoon over Kerala around June 1, IMD said in its Saturday bulletin.

IMD’s forecasts provide information to at least 700 million people in India, who are dependent on agriculture for livelihood. The monsoon is crucial for the yield of rice, wheat, sugarcane, and oilseeds in a country where farming accounts for about 15% of the economy but employs over half of its people.