The Climate Prediction Centre (CPC), an arm of the US weather agency National Oceanic and Atmospheric Administration (NOAA), has raised the chances of La Nina emerging during the September-November 2024 period, though it could turn out to be a \u201cweak\u201d one.<\/p>\n
\u201cLa Ni\u00f1a is favoured to emerge in September-November (71 per cent chance) and is expected to persist through January-March 2025,\u201d the CPC said in its latest update on Thursday.\u00a0<\/p>\n
The continuation of negative subsurface temperatures and enhanced low-level easterly wind anomalies supports the formation of a weak La Ni\u00f1a. \u201cA weaker La Ni\u00f1a implies that it would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance,\u201d said the US weather agency.<\/p>\n
\nUp 5 percentage points
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Last month, CPC said there was a 66 per cent chance of La Nina emerging during September-November. It said El Nino-Southern Oscillation (ENSO) neutral conditions were expected to continue for the next several months. It also said there was a 74 per cent chance for La Nina to persist through the Northern Hemisphere winter 2024-25 (November-January).<\/p>\n
The US weather agency said ENSO-neutral conditions continued during August 2024, with near-average sea surface temperatures (SSTs) observed across most of the equatorial Pacific Ocean.\u00a0<\/p>\n
\u201cThis month, the (CPC) team relies more on the latest North American Multi-Model Ensemble (NMME) guidance, which predicts La Ni\u00f1a to emerge in the next couple of months and continue through the Northern Hemisphere winter,\u201d it said.\u00a0<\/p>\n
Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral. \u201cThe IRI (International Research Institute for Climate and Society) plume predicts a weak and short duration La Ni\u00f1a, as indicated by the Ni\u00f1o-3.4 index values less than -0.5 C,\u201d CPC said.\u00a0<\/p>\n
\nBoM predictions
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Last week, Australia\u2019s Bureau of Meteorology (BoM) said \u00a0ENSO and Indian Ocean Dipole (IOD) will remain neutral during the southern hemisphere spring (September 22-December 22).\u00a0<\/p>\n
It said its model indicated a neutral but cooler-than-average ENSO state. Of the remaining 6 international models BoM surveyed by the Bureau, 3 indicate SSTs (Sea Surface Temperatures) in the central tropical Pacific remaining within historically ENSO-neutral values (between \u22120.8 \u00b0C and +0.8 \u00b0C), and 3 indicate SSTs exceeding the La Ni\u00f1a threshold (below \u22120.8 \u00b0C) from October.\u00a0<\/p>\n
CPC, however, said the weekly Ni\u00f1o indices did not change substantially during August, with the latest weekly index values varying between +0.2C (Ni\u00f1o-4) and -0.4C.\u00a0\u201cBelow-average subsurface temperatures were also similar to those in early August. Negative temperature anomalies continued to dominate across most of the subsurface equatorial Pacific Ocean,\u201d it said.<\/p>\n