Dramatic Warming Equatorial Pacific Subsurface Signals An El Nino Trend

Fig. 1: DRAMATIC warming of the equatorial subsurface Pacific Ocean was observed in March 2023. Fuel for El Nino ahead is building!

Discussion: In March, the subsurface equatorial Pacific warmed dramatically. Each NINO region of the equatorial Pacific subsurface is now in support of an El Nino development trend. The change from February is dramatic…much warmer! Normally, the observational trend of subsurface temperature anomalies in the equatorial Pacific can foreshadow a possible phase change of ENSO. In the equatorial East Pacific subsurface, a Kelvin Wave pushed just east of 140W while waters off the northwest coast of South America continue warming. Eastward pulsing of the Madden Julian oscillation (MJO) has caused the subsurface warming in the equatorial East Pacific coincidentally with neutral to negative daily southern oscillation index (SOI) which is a sign that the long-lasting La Nina climate pattern is breaking down. At the surface, the Nino12 SSTA off the northwest coast of South America continues very warm while the remaining Nino regions extending westward to the east of the Dateline are neutral. Bottom line? ENSO is in neutral phase. Diagnostics are surging toward El Nino support. Dynamic models remain aggressive with a strong El Nino for the second half of 2023. Statistical/analog forecast models are weaker with El Nino. We’re in the ENSO springtime prediction barrier. Forecast confidence in the ENSO forecast increases dramatically in about 4-6 weeks.

Fig. 2: The subsurface equatorial Pacific Ocean finds an east-shifting Kelvin Wave extending east of 140W while waters off northwest South America continue to warm. All signs of support for El Nino ahead!

Fig. 3: The subsurface warming is impressive but most Nino SSTA regions are right at neutral to determine ENSO phase.