ENSO-neutral conditions continued during November 2019, although the Southern Oscillation Index (SOI) dipped into El Niño territory and sea surface temperatures (SSTs) were on the El Niño side of neutral.
The NINO3.4 Index (in the central Pacific) for the month of November was +0.64 ̊C, an increase compared to October. Warmth was steadfast in the NINO4 region (west-central Pacific) with a monthly value of +0.89 ̊C. Upper-oceanic heat content anomalies remained above average to the west of the Date Line. East of the Date Line, upper-oceanic heat content decreased to neutral or slightly negative anomalies over the past month.
While the ENSO status will most likely “neutral” over the next season, the atmosphere may respond to warmer than average SSTs in the tropical western Pacific Ocean.
During the first 10 days of December, weaker than normal trade winds are forecast in the vicinity of the NINO3 and NINO3.4 regions. Stronger than normal trade winds are then forecast across much of the basin from mid-December.
According to the consensus from international models, ENSO-neutral conditions are most likely (70% chance) for the December 2019 – February 2020 period. For the March – May 2020 period, the probability for ENSO-neutral conditions is 63% and 55% for the June – August 2020 period.