Pacific Ocean SSTs consistent with weak El Nino, says US weather agency

A weak El Nino has set in with above-average sea surface temperatures (SSTs) across the central and eastern Pacific Ocean, the Climate Prediction Center (CPC), an arm of the US National Oceanic and Atmospheric Administration, has said.

In an update presented this week, the CPC said the tropical Pacific atmospheric anomalies are consistent with weak El Nino conditions. However, there is a 90 per cent chance that El Nino will continue through the Northern Hemisphere winter (March 2024).

“In the last four weeks, equatorial SSTs were above average across most of the Pacific Ocean, with near-average SSTs present near the western Pacific Ocean,” it said.

Positive anomalies over eastern Pacific

During the same period, equatorial sea surface temperatures have been higher across most parts of the Pacific Ocean and parts of the Indian and Atlantic Oceans. “SSTs near Ecuador and Peru remain strongly above average,” the CPC said.

In particular, in the eastern Pacific Ocean, the anomalies had turned positive over the past four weeks. Other indications also pointed to the El Nino phenomenon, which results in drought in Asia, particularly India, where it could affect rainfall during the south-west monsoon.

The CPC said the weekly SST departure was 1.1 degrees C for El Nino 3.4, an index that represents average equatorial anomalies across the Pacific Ocean and typically uses a 3-month running mean where El Nino or La Nina are defined when SSTs exceed + or – 0.4 degrees C.

Outlook upgrades

“Nearly all models indicate El Niño will persist through the Northern Hemisphere winter of 2023–24. A strong El Niño is indicated by the dynamical model average through December 2023–February 2024,” it said.

Last week, the Australian Bureau of Meteorology changed its El Nino outlook to “alert” from “watch”, a signal that the weather event is on.

On July 4, the World Meteorological Organization, an arm of the UN, declared the onset of El Nino.