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El Niño Watch 2018
Mon Aug 27, 2018 9:35am
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EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC
DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP/NWS
and the International Research Institute for Climate and Society
9 August 2018
ENSO Alert System Status: El Niño Watch
Synopsis: There is ~60% chance of El Niño in the Northern Hemisphere fall 2018 (SeptemberNovember),
increasing to ~70% during winter 2018-19.
ENSO-neutral continued during July, as indicated by near-average sea surface temperatures
(SSTs) across the central and eastern equatorial Pacific at the end of the month (Fig. 1). The latest weekly
Niño indices were 0.0C for the Niño-3 index, +0.1C for the Niño-3.4 and Niño1+2 indices, and +0.4C
for the Niño-4 index (Fig. 2). Positive subsurface temperature anomalies (averaged across 180°-100°W)
continued over the past month (Fig. 3), and the volume of anomalous warmth extended to the surface in
the eastern part of the basin (Fig. 4). Convection remained suppressed near the Date Line and over
western Indonesia (Fig. 5). Low-level winds were near average across most of the equatorial Pacific
Ocean, while upper-level wind anomalies were westerly over the eastern Pacific and near the
International Date Line. Overall, the oceanic and atmospheric conditions reflected ENSO-neutral.
The majority of models in the IRI/CPC plume predict ENSO-neutral to continue during the
remainder of the Northern Hemisphere summer 2018, with El Niño most likely thereafter (Fig. 6). Model
predictions for El Niño have not wavered despite the recent decrease in the positive SST anomalies in
portions of the eastern Pacific. Because of the consistency of forecasts and the expected eventual
resurgence in the low-level westerly wind anomalies, the forecasters still favor the onset of El Niño in the
coming months. In summary, there is ~60% chance of El Niño in the Northern Hemisphere fall 2018
(September-November), increasing to ~70% during winter 2018-19 (click CPC/IRI consensus forecast for
the chance of each outcome for each 3-month period).
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration
(NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric
conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current
Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum of CPC's
Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog.
The next ENSO Diagnostics Discussion is scheduled for 13 September 2018. To receive an e-mail
notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message
to: ncep.list.enso-update@noaa.gov.
Climate Prediction Center
National Centers for Environmental Prediction
NOAA/National Weather Service
College Park, MD 20740
Maps and charts
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

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