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: La Niña Advisory
transition from La Niña to ENSO-neutral is most likely (~55% chance) during the
March-May season, with neutral conditions likely to continue into the second
half of the year.
During February 2018, La Niña
weakened, but was still reflected by below-average sea surface temperatures
(SSTs) in the east-central equatorial Pacific Ocean (Fig. T18). The monthly index
values were -0.9°C and -1.0°C in the Niño-3.4
and Niño-3 regions, respectively, and were less negative in the surrounding
Niño.4 and Niño1+2 regions (Table T2). While negative anomalies were
maintained near the surface, the sub-surface temperature anomalies (averaged
across 180°-100°W) warmed to near zero. This warming was due to the eastward
propagation of above-average temperatures along the thermocline in association
with a downwelling equatorial oceanic Kelvin wave (Fig. T17). The atmospheric anomalies typical of La Niña
weakened considerably across the tropical Pacific. Convection was suppressed near Indonesia and
was only weakly enhanced over the far western Pacific (Fig. T25). Also, low-level wind anomalies were westerly
over the western and central Pacific, while upper-level winds remained
anomalously westerly over the eastern Pacific (Figs. T20, T21). Overall, the ocean and atmosphere system
suggests La Niña is weakening.
Most models in the IRI/CPC
plume predict La Niña will decay and return to ENSO-neutral during the Northern
Hemisphere spring 2018 (Figs. F1-F13). The forecast
consensus similarly favors a transition during the spring, with a continuation
of ENSO-neutral conditions through the summer.
In summary, a transition from La Niña to ENSO-neutral is most likely
(~55% chance) during the March-May season, with neutral conditions likely to
continue into the second half of the year.
Weekly updates of oceanic and
atmospheric conditions are available on the Climate Prediction Center homepage
Niño/La Niña Current Conditions and Expert Discussions).