The fast-warming tropical Pacific is pointing to a major event, but a crucial weakening of trade winds – capable of turbocharging or throttling the phenomenon – has yet to materialise.
Scientists say these interactions are notoriously complex and difficult to predict – making it too early to confidently forecast how powerful this El Nino could become.
The US National Oceanic and Atmospheric Administration (NOAA) says there is about an 80 percent chance of El Nino developing by July.
Sea temperatures in key El Nino zones of the equatorial Pacific are rapidly rising, and an enormous pool of abnormally warm water is massing beneath the surface.
Several leading weather services are predicting Pacific sea temperatures could surge 2.5 degrees Celsius or more above average later this year – exceptionally high projections.
Just three events – 1982/83, 1997/98 and 2015/16 – have breached the two degree Celsius mark since the first major El Nino recorded in the modern era in 1877/78.
Adam Scaife, head of long-range prediction at the UK Met Office, said this El Nino could be the strongest in decades or “even be of record strength”.
“There’s definitely something coming. We’re very confident about that, and it looks like it will be a big event,” he said.
NOAA forecasts a one-in-three chance this episode will hit two degrees or above – crossing into what is dubbed “super El Nino” territory.
But key pieces of the puzzle had yet to fall into place, said Michelle L’Heureux, NOAA’s El Nino-Southern Oscillation lead.
El Ninos build strength as the ocean and atmosphere increasingly “couple” over the summer months, shifting air pressure, cloud patterns and winds.
This feedback loop can turn a modest El Nino into a blockbuster event, supercharging heat and triggering chaotic weather worldwide. (AFP)
