The South-West monsoon is expected to reach Central India between June 14 and 22, according to an early forecast method developed at the Potsdam Institute for Climate Impact Research.

The time line suggested by the German institute more or less corresponds with the normal dates of monsoon onset in the region set by India Met Department.

Data analysis

The institute has based its prediction on an analysis of observational data that equipped it to declare the onset date more than a month in advance in Central India.

Elena Surovyatkina led this study which showed to be successful last year. The monsoon onset date is of crucial importance for Indian farmers feeding a population of more than one billion, she said.

Climate change will likely affect monsoon stability and hence makes accurate forecasting even more important, she said.

Although the rainy season happens annually between June and September, the time of monsoon season’s onset and withdrawal varies within a month from year to year.

Significant challenge

“The important feature of the monsoon is that it starts and ends suddenly. Hence, forecasting it remains a significant scientific challenge,” says Surovyatkina.

“However, this helped me to realise that the sudden onset of monsoon means a threshold behaviour, and inspired me to apply the theory of critical transition for a prediction of monsoon.”

The long-term forecast means 40 days in advance for the onset date, and 70 days in advance for the withdrawal date. The prognosis is provided yearly before and during the monsoon season.

Local events such as a pair cyclones from both sides of Indian subcontinent can stop the monsoon for a week. Such random events are unpredictable. In such cases, the forecast will be updated.

A forecast for the monsoon withdrawal will be issued on July 27, Surovyatkina said.