El Nino, a weather impact created by warming of the ocean water, will likely peak during November-January with models indicating further warming of central to eastern Pacific, two global weather agencies have said in their forecast this week. 

“At its peak (November-January), nearly all models suggest a moderate-to-strong El Nino,” said the Climate Prediction Centre (CPC), an arm of the US weather agency National Oceanic and Atmospheric Administration, on Monday. 

“Oceanic indicators firmly exhibit an El Nino state. Central and eastern Pacific sea surface temperatures (SSTs) continue to exceed El Nino thresholds. Models indicate further warming of the central to eastern Pacific is likely,” the Australian Bureau of Meteorology (BoM) said on Tuesday.

Rescue for India

El Nino, typically, results in prolonged dry periods and drought in Asia. It also impacts the Indian South-West monsoon as was seen during June and August this year. 

However, a positive Indian Ocean Dipole (IOD) — which results in temperatures being different in the western and eastern parts of the Indian Ocean — could rescue India from the impact of El Nino when it turns severe in November. 

BoM said the positive IOD continues to strengthen with its index rising to +1.85 °C for the week ending 8 October.

“This is the sixth-highest weekly IOD index value since records for the Bureau SST dataset began in 2001, with all higher index values observed during the positive IOD of 2019,” the Australian weather agency said.

All models predict the positive IOD to continue till December, which could result in reduced rainfall in Australia. This will likely impact South-East Asia, too, and the region may face a dry period. 

To exist until Feb

On the other hand, the positive IOD will likely bring rains to India, particularly the southern peninsula. But BoM said when a positive IOD and El Nino occur together, their drying effect is typically stronger and more widespread, mainly across Australia.

The Australian weather agency said signs signify that the atmosphere is responding to warm SSTs over the Pacific and a coupling of Ocean and atmosphere is occurring.  

“This coupling is a characteristic of an El Nino event and is what strengthens and sustains an event for an extended period,” BoM said. 

Climate models indicate that El Nino is likely to persist until at least the end of February, the Australian weather agency said. The CPC said El Nino is anticipated to continue through the Northern Hemisphere winter,  with a greater than 95 per cent chance through January-March 2024.

The US weather arm said during the last four weeks, equatorial SSTs were above average across most of the Pacific Ocean, in the western Indian Ocean, and across much of the Atlantic Ocean. Equatorial SSTs were below average in the eastern Indian Ocean, a succour for India. 

The Ocean Nino Index value for July-September 2023 was 1.3º C, which is above average and a clear indication of El Nino at play.