During July, ENSO-neutral conditions were reflected by the combination of below-average sea surface temperatures (SSTs) in the eastern equatorial Pacific Ocean and above-average SSTs in the central Pacific [Fig. 1]. The latest weekly ENSO indices were +1.0°C, +0.5°C, -0.2°C and -0.5°C in the Niño-4, Niño-3.4, Niño-3 and Niño-1+2 regions, respectively [Fig. 2]. Upper-ocean subsurface temperatures (averaged across 180°-100°W) were near average throughout the month [Fig. 3], as anomalously cool waters prevailed in the eastern Pacific and anomalously warm waters continued in the central Pacific [Fig. 4]. Suppressed tropical convection continued over Indonesia, while near-average convection was observed near the Date Line [Fig. 5]. Low-level wind anomalies were near average over the tropical Pacific Ocean, and upper-level winds were easterly over the east-central Pacific. The traditional and equatorial Southern Oscillation Indices remained slightly negative. Overall, oceanic and atmospheric conditions were consistent with a transition to ENSO-neutral.
The latest IRI/CPC plume of forecasts of the Niño-3.4 index [Fig. 6] favors ENSO-neutral (Niño-3.4 index between -0.5°C and +0.5°C), with index values greater than zero from late Northern Hemisphere summer into fall, warming closer to the El Niño threshold (+0.5°C) by winter. Atypically, dynamical models forecast weaker positive SST anomalies than statistical models throughout most of the forecast period. As a result, while forecasters favor ENSO-neutral conditions, the odds of El Niño (~30%) are roughly twice that of La Niña for next winter. In summary, El Niño has transitioned to ENSO-neutral, which is most likely to continue through Northern Hemisphere winter 2019-20 (50-55% chance; click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).