Normal rainfall likely but south India, North-East may battle shortfalls

The nation is going to experience 'normal' monsoon and it will be 100 per cent of the long-period average of 887mm from June till September, private weather forecaster Skymet said in its monsoon forecast on Wednesday. The margin of error in their forecast is +/-5%. However, there are chances of below par rainfall in the peak months of July and August in southern India, and a major portion of the north-east may receive deficient rains.

Unlike earlier forecasts, Skymet did not mention any specific date for the onset of monsoon this year.

"Skymet expects that peninsular India, along with major portion of northeast India, is likely to be at a higher risk of being rain deficient throughout the season. July and August may see comparatively lesser rainfall.

To be precise, August, would be a shade poorer than July," a statement issued by Skymet stated.

On a monthly average, July may receive 97% rainfall of the long-period average, which is 289mm and there are 30 % chances of July rain being below par, whereas there is a 35 % chance of August rain being below par.

"Devolving La Niña and gradual warming of Pacific is ruling out the possibility of excess rains," said Jatin Singh, chief executive officer, Skymet. The company's chief meteorologist Mahesh Palawat said, "As of now, La Niña is prevailing over Pacific Ocean, but it is weak. The La Niña conditions are likely to be neutral during the peak months. The Indian Ocean Dipole (IOD) is likely to be neutral for most of the monsoon and may become normal only during the later part."

IOD, one of the several strong factors affecting the monsoons, is the difference between sea surface temperatures in the western and eastern equatorial Indian Ocean. A positive IOD favours monsoon systems on India's west coast.

The IOD factor

The Indian Ocean Dipole (IOD) is likely to be neutral for most of the monsoon and may become normal only during the later part