Rain wallops Delhi, Mumbai as IMD projects bountiful September

The first day of September brought a deluge to both New Delhi and Mumbai after the India Meteorological Department (IMD) projected above normal rainfall for the month (110 per cent-plus of the Long-Period Average) that should help rein in the prevailing rain deficit and end the season at ‘the lower end of normal.’

Private forecaster Skymet Weather said September began with a bang over Delhi and the NCR region, with the city recording rain from the early morning hours on Wednesday. The region received rain on yhe previous evening, too, with Safdarjung recording 11.2 cm until Wednesday morning.

Delhi, Mumbai drenched

Almost similar conditions prevailed over Mumbai, which witnessed rain in three-digit figures till Wednesday morning. Waterlogging was reported from some parts of the city. Santa Cruz recorded 10.8 cm of rainfall, while Thane saw even higher rainfall at 15 cm. Colaba recorded a moderate 5.7 cm.

The rain over the national capital and the commercial capital could be attributed to a cyclonic circulation from a previous low-pressure area that the IMD located on Wednesday evening over South Gujarat, and a trough originating from it and being routed to North-West Uttar Pradesh across East Rajasthan.

‘Lower end of normal’ season

Apart from this, the main monsoon trough runs along its normal alignment but may start shifting northward from Friday, likely reducing the intensity of the rainfall over West and North-West India. The next meaningful revival in rainfall is forecast to occur over the South Peninsula from Saturday.

Earlier on Wednesday, the IMD predicted that the 2021 monsoon season should end ‘around the lower end of normal’ thanks to an expected surge in rainfall this month (September, the last of the season), according to Mrutyunjay Mohapatra, Director-General.

Major August deficit

The Long-Period Average of rainfall during September, the last of the four monsoon months, is based on the data of 1961-2010, and is about 170 mm. Considering the expected above normal rainfall activity, the current deficit of nine per cent is likely to reduce, Mohapatra said at a virtual press conference in Delhi.

The monsoon was mainly impacted by an unexpectedly huge rainfall deficit of 24.1 per cent during August, normally the second rainiest month after July. Mostly, August rain deficits are associated with El Nino and negative Indian Ocean Dipole (IOD) events (approximately nine in 15 years).

“We may not have an El Nino in the tropical Pacific, but the latest global model forecasts indicate that the prevailing ‘cool neutral’ (neither El Nino nor La Nina, but with a bias towards the latter) conditions are likely to continue as would the negative IOD conditions over the Indian Ocean during September.

La Nina may re-emerge

However, sea-surface temperatures over the Central and East Equatorial Pacific Ocean show a cooling tendency and there is an increased possibility of re-emergence of La Nina conditions at the end of the monsoon season or thereafter, Mohapatra said, in terms of the short to medium-term outlook.

“As the sea surface temperature conditions over the Pacific and the Indian Oceans are known to have a strong influence on the Indian monsoon, the IMD is carefully monitoring the evolution of sea surface conditions over these ocean basins during the rest of the year as well.

The forecast for September suggests that above normal to normal rainfall is likely over many areas of Central India. Normal to below normal rainfall is most likely over many areas of North-West and North-East India and the southern most parts of Peninsular India (parts of Kerala and Tamil Nadu).

Above normal rain until November

BusinessLine had reported two days ago that the South-West monsoon is expected to be normal in September, while the country is forecast to get above-normal rainfall during September-November this year, quoting D.S. Pai, Head - Climate Research and Services, at IMD, Pune.

“Over the last 10-11 years we have received good rainfall during September. Rainfall even during September-November has been good. Better days are ahead,” he said while addressing a Kharif sowing overview webinar.

Rainfall would very likely be near normal in the first week of September and normal to above normal during the second week over Central and adjoining North-West and North Peninsular India; near normal over most parts of the East and North-East, and below normal over most parts of Peninsular India.

COMMENT NOW