Forecast Forum
The canonical correlation analysis (CCA) forecast of
SST in the central Pacific (Barnett et al. 1988, Science, 241,
192‑196; Barnston and Ropelewski
1992, J. Climate, 5, 1316‑1345), is shown in Figs. F1 and F2. This forecast is produced routinely by the
Prediction Branch of the Climate Prediction Center. The
predictions from the National Centers for Environmental Prediction (NCEP)
Coupled Forecast System Model (CFS03) are presented in Figs. F3 and
F4a, F4b. Predictions from the
Markov model (Xue, et al. 2000: J. Climate, 13,
849‑871) are shown in Figs. F5 and F6. Predictions from the latest version of the
LDEO model (Chen et al. 2000: Geophys. Res.
Let., 27, 2585‑2587) are shown in Figs. F7
and F8. Predictions using linear inverse modeling (Penland and Magorian 1993: J.
Climate, 6, 1067‑1076) are shown in Figs. F9 and F10. Predictions from the Scripps / Max Planck
Institute (MPI) hybrid coupled model (Barnett et al. 1993: J. Climate, 6,
1545‑1566) are shown in Fig. F11.
Predictions from the ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea.
Forecasting, 12, 633‑652) are shown in Fig. F12. Niño 3.4 predictions are summarized in Fig.
F13, provided by the Forecasting and Prediction Research Group of the IRI.
The CPC and the contributors to the Forecast Forum caution
potential users of this predictive information that they can expect only modest
skill.
ENSO Alert System Status: El Niño Watch
Outlook:
There
is ~60% chance of El Niño in the Northern Hemisphere fall 2018 (September-November),
increasing to ~70% during winter 2018-19.
Discussion:
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. T18). The monthly Niño indices were -0.2°C for the Niño-1+2 index, +0.3°C for the Niño-3.4 and Niño-4 indices, and +0.4°C for the Niño-3 index (Table T2). Positive subsurface temperature anomalies
(averaged across 180°-100°W) continued over the past month, and the volume of
anomalous warmth extended to the surface in the eastern part of the basin (Fig. T17).
Convection remained suppressed near the Date Line and over western Indonesia (Fig. T25). Low-level winds were
near average across most of the equatorial Pacific Ocean (Fig. T20), while upper-level
wind anomalies were westerly over the eastern Pacific and near the
International Date Line (Fig. T21). 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 (Figs. F1-F13). 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.
Weekly
updates of oceanic and atmospheric conditions are available on the Climate
Prediction Center homepage (El
Niño/La Niña Current Conditions and Expert Discussions).