Fig. 1: Current equatorial Pacific Ocean upper ocean heat analysis.
Fig. 2: Last year at this time equatorial Pacific upper ocean heat.
Fig. 3: NCEP CFS V2 Nino34 SSTA forecast.
Discussion: During the past 7-10 days the subsurface east-central equatorial Pacific Ocean has turned sharply cooler (Fig. 1). Compared to last year, the amplitude of the cool signature this year is stronger than last including a less warm subsurface West Pacific in 2021 (Fig. 2). The NCEP CFS V2 identifies the cooler subsurface and applies the cooler regime to the forecast and the result is a stronger La Nina developing during quarter 4 of 2021 (Fig. 3). Cooling of the Gulf of Alaska the past 14 days discussed in the previous report and persistence of cool phase Pacific decadal oscillation (-PDO) also cause the NCEP CFS V2 to trend toward a stronger La Nina forecast for late 2021/early 2022, stronger than last year.