FXUS24 KWNC 141403 PMDENS El Nino/Southern Oscillation (ENSO) Diagnostic Discussion NWS Climate Prediction Center College Park MD 900 AM EST Thu 14 Nov 2024 NOTE: figures mentioned in the discussion are available on the internet at HTTP://WWW.CPC.NCEP.NOAA.GOV ENSO Alert System Status: La Nina Watch Synopsis: La Nina is most likely to emerge in October-December 2024 (57percent chance) and is expected to persist through January-March 2025. Over the past month, ENSO-neutral continued, as evidenced by overall near-average sea surface temperatures (SSTs) observed across the central and eastern equatorial Pacific Ocean (Fig. 1). Similar to last month, the latest weekly Nino indices ranged from +0.2degC (Nino-4) to -0.3degC (Nino-3.4; Fig. 2). Below-average subsurface temperatures persisted (Fig. 3) across the east-central and eastern equatorial Pacific Ocean (Fig. 4). For the monthly average, low-level wind anomalies were easterly over a small region of the east-central equatorial Pacific, and upper-level wind anomalies were near average. Convection was suppressed over the Date Line and was weakly enhanced over eastern Indonesia (Fig. 5). The traditional and equatorial Southern Oscillation indices were positive. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral. The IRI plume predicts a weak and a short duration La Nina, as indicated by the Nino-3.4 index values less than -0.5degC (Fig. 6). The latest North American Multi-Model Ensemble (NMME) forecasts are cooler than the IRI plume and predict a weak La Nina. Due to this guidance and La Nina-like atmospheric circulation anomalies over the tropics, the team still favors onset of La Nina, but it is likely to remain weak and have shorter duration than other historical episodes. A weak La Nina would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance (e.g., CPC's seasonal outlooks). In summary, La Nina is most likely to emerge in October-December 2024 (57percent chance) and is expected to persist through January-March 2025 (Fig. 7). This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center website (El Nino/La Nina Current Conditions and Expert Discussions). Additional perspectives and analyses are also available in an ENSO blog. A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 12 December 2024. To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: ncep.list.enso-update@noaa.gov. $$