The southwest monsoon is just around the corner and India is waiting to embrace the cool showers after two months of extreme temperature.

“The conditions are favourable for advancement of monsoon. The forecast is on track as the estimate for the monsoon onset in Kerala allows a standard deviation of 6 days,” Dr Sivananda Pai, Scientist at the Environmental Monitoring and Research centre, IMD told Onmanorama.

The India Meteorological Department (IMD) has predicted that the monsoon will hit Kerala coast by June 4. But with the possibility of El Nino looming large, many are worried whether India will witness a below normal monsoon this year.

According to Dr Pai, the country need not worry about a below average rainfall despite the El Nino conditions which will develop during the monsoon.

“The rains are expected to total 96% of the long-term average this year,” he said.

The IMD defines average or normal rainfall as ranging between 96% and 104% of the 50-year average of 87 cm (35 inches) for the four-month season.

“La Nina conditions are currently almost absent over Equatorial Pacific. ENSO neutral conditions are prevalent now. According to estimates, El Nino conditions will develop over Equatorial Pacific with 90% probability during the monsoon season. It will peak in December and January. It will have an impact on subsequent summer months.”

“El Nino will have a negative impact on monsoon. The prediction is only 96% of LPA due to this,” Dr Pai said.

“However, strong position of the Indian Ocean dipole over Equatorial Indian Ocean will favour a good monsoon. Negative and positive effects could balance each other out,” he added.

The El Nino is a weather phenomenon caused by a warming of the central Pacific Ocean waters off South America that typically results in hot and dry weather in Southeast Asia and other parts of the world. The Indian Ocean Dipole (IOD) is defined by the difference in sea surface temperature between two areas (or poles).

In the past, India has experienced below-average rainfall during most El Nino years, sometimes leading to severe droughts that destroyed crops and forced authorities to limit the export of some grains.

Distribution

Though the country received an above normal monsoon last year with around 105-110% of the long period average rainfall, the distribution has not always been equal. Though the southern peninsula in particular received 122% of LPA, around 40% of the country received deficit rainfall last year. Around six states including UP, Bihar and Jharkhand even faced a drought situation.

According to Dr Pai, the variation distribution is not unusual. "The distribution varies from year to year. It is unique every year. This is nothing out of the ordinary,” he said.

“At the regional scale, IMD has predicted northwest region to get below normal rainfall this year. Other subregions like southern, central and northeast will receive normal rainfall," he said.

In the southern region, certain pockets of Kerala and Tamil Nadu will experience above normal rainfall.

Extreme rainfall events

According to Dr Pai, extreme rainfall events are becoming increasingly common in recent years due to the impact of climate change.

“Even in below normal rainfall years, we are witnessing extreme rainfall events in Kerala. This can be attributed to climate change associated with global warming. The total monsoon rainfall in Kerala shows a negative trend but extreme events are increasing,” he said.

“Due to the land use pattern changes, this has an exacerbated effect on Kerala. The urban nature of the state and high population density is not helping. The water is no longer quickly moving to the sea due to excessive construction work and lack of drainage facilities. Paving of surfaces with tiles have also prevented water from trickling down leading to urban flooding,” he added.