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
ENSO Alert System Status: Not Active
and El Niño are nearly equally favored during the Northern Hemisphere summer
and fall 2017.
persisted during April, with near-average sea surface temperatures (SSTs) observed
across the central equatorial Pacific and above-average SSTs in the eastern
Pacific (Fig. T18). The monthly Niño index values were
+0.6°C in Niño-3, +0.3°C in Niño-3.4, and +0.2 and +0.9°C in the Niño-4 and
Niño-1+2 regions, respectively (Table T2). The upper-ocean heat content
anomaly was slightly positive during April, reflecting the strengthening of
above-average temperatures at depth around the Date Line (Fig. T17). Atmospheric
convection anomalies were weak over the central tropical Pacific and Maritime
Continent (Fig. T25), while the lower-level and
upper-level winds were near average over most of the tropical Pacific (Figs T20 & T21). Overall, the ocean and atmosphere system
remains consistent with ENSO-neutral.
models predict the onset of El Niño (3-month average Niño-3.4 index at or
greater than 0.5°C) during the Northern Hemisphere summer (Figs. F1-F12).
However, the NCEP CFSv2 and most of the statistical models are more
conservative and indicate that while the Niño-3.4 index may be near or greater
than +0.5°C for several months, the warmth may not last long enough to qualify
as an El Niño episode (5 consecutive overlapping seasons) and/or may not
significantly impact the atmospheric circulation. Relative to last month, the forecaster
consensus reflects slightly lower chances of El Niño (~45%), in part due to the
conflicting model guidance and lack of a clear shift toward El Niño in the
observational data. In
summary, while chances are slightly lower than 50%, ENSO-neutral and El Niño are nearly equally favored during the Northern
Hemisphere summer and fall 2017.
updates of oceanic and atmospheric conditions are available on the Climate
Prediction Center homepage (El
Niño/La Niña Current Conditions and Expert Discussions).