india

Updated: May 16, 2019 07:23 IST

The monsoon is likely to set in over Kerala on June 6, five days later than it usually does, according to a statement the India Meteorological Department (IMD) issued on Wednesday. Last year, the monsoon arrived early, on May 29.

On Tuesday, Skymet Weather forecast the monsoon arrival date to be June 4 with an error margin of two days. IMD also has an error margin of four days.

IMD said in its statement that the southwest monsoon typically sets in over Kerala on June 1 with a standard deviation of about 7 days.

IMD has categorised the onset this year to be “slightly delayed”. Agriculture experts said a delay of five days in the arrival of the monsoon is likely to have serious implications for farmers who will start preparing their fields for kharif or monsoon crops.

IMD uses six predictors for the models, including the minimum temperatures over north-west India. The other predictors are premonsoon rainfall peak over the southern peninsula; Outgoing Longwave Radiation (OLR) or the total radiation going to space emitted by the atmosphere over the South China Sea.

IMD has forecast a “near normal” at 96% of the Long Period Average (LPA) received during the monsoon months in the 19512000 period, in its initial forecast issued in April. But private met forecaster, Skymet Weather, has forecast (and reiterated in an update on Tuesday) a “below normal” monsoon to the tune of 93% of the LPA. It has also predicted monsoon rains to be under normal in all four divisions of the country.

IMD officials said there is no direct link between a delayed onset and persisting El Nino conditions although some recent research studies do find a relationship between the two. “Some research studies say El Nino has a slight impact on onset of monsoon, but it’s local factors which influence the onset date much more than El Nino. However, a delayed onset has nothing to do with the amount of rain we receive during the monsoon season,” said DS Pai, senior scientist at IMD Pune.

Pai added that IMD will come out with a monsoon forecast update later this month. The forecast issued in April still holds good but there may be minor updates and region wise breakup of rainfall forecast, Pai said.

G V Ramanjaneyulu, executive director, Centre for Sustainable Agriculture, said a delay in the monsoon’s onset would mean a corresponding delay in sowing of kharif crops such as rice, red gram and cotton. “Delay of each day in the onset of monsoon will have an impact on yields. Farmers start preparing land in May and sowing by June second week. By the beginning of winter, these crops complete their life cycle so any delay affects the crop cycle.”

Experts have noted that deficiency in pre-monsoon showers also affects soil moisture and land preparation for kharif crops. Pre-monsoon rain has been 21% below the LPA of 82.5 mm between March 1 and May 8, according to IMD.