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: El Nino Advisory
There is an
approximately 50-60% chance that El Nino conditions will continue through
Northern Hemisphere summer 2015.
February 2015, El Nino conditions were observed as the above-average sea
surface temperatures (SST) across the western and central equatorial Pacific (Fig.
T18) became weakly coupled to the tropical
atmosphere. The monthly Niño indices
were +0.6C in the Nino-3.4 region, +1.0C in the Nino-4 region, +0.2C in the Nino-3
region, and -0.6C in the Nino-1+2 region (Table
T2). Subsurface temperature anomalies increased in
association with a downwelling equatorial oceanic
Kelvin wave, which was reflected in positive subsurface anomalies across most
of the equatorial Pacific (Fig. T17). Consistent with weak
coupling, the frequency and strength of low-level westerly wind anomalies
increased over the equatorial Pacific during the last month and a half (Fig.
T13). At upper-levels, anomalous easterly winds
persisted across the east-central Pacific (Fig. T21). Also, the
equatorial Southern Oscillation Index (EQSOI) remained negative for two
consecutive months (Fig. T2). Convection was enhanced over the western
equatorial Pacific and near average around the Date Line (Fig. T25). Overall,
these features are consistent with borderline, weak El Nino conditions.
to last month, several more models indicate El Nino (3-month values of the Nino-3.4
index equal to or greater than 0.5C) will continue throughout 2015 (Figs.
F1-F13). This result is supported by the
recent increase in subsurface temperatures and near-term model predictions of
the continuation of low-level westerly wind anomalies
across parts of the equatorial Pacific.
However, model forecast skill tends to be lower during the Northern
Hemisphere spring, which contributes to progressively lower probabilities of El
Nino through the year. In summary, there is an approximately 50-60% chance that
El Nino conditions will continue through Northern Hemisphere summer 2015.
updates of oceanic and atmospheric conditions are available on the Climate
Prediction Center homepage (El
Nino/La Nina Current Conditions and Expert Discussions).