Fig. 1: Subsurface equatorial East Pacific temperature anomalies identify dramatic warming.
Discussion: The upper ocean heat in the equatorial East Pacific is warming sharply (Fig. 1). An old Kelvin Wave shifting eastward arrived on the northwest coast of South America the past 1-2 weeks and has caused steady impressive warming in the Nino12 SSTA region (Fig. 2). A new Kelvin Wave has shifted east of the Dateline to about 145-140W longitude. The new Kelvin Wave is forecast to reach the northwest South America coast by early May. At that time, oceanic El Nino will begin to emerge with onset by June. The southern oscillation index (SOI) is near zero for March. Several months of a negative SOI is required to shift the global climate pattern to El Nino which is likely by July.
Fig. 2: The 12-week Nino SSTA tracker reveals ENSO has warmed into neutral phase based on the Nino34 SSTA observations.