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. Niņo 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 Niņo Advisory
Outlook:
Weak
El Niņo conditions are present and are expected to continue through the
Northern Hemisphere spring 2019 (~55% chance).
Discussion:
El Niņo conditions formed
during January 2019, based on the presence of above-average sea surface
temperatures (SSTs) across most of the equatorial Pacific Ocean (Fig. T18) and corresponding changes in
the overlying atmospheric circulation.
The monthly Niņo indices remained above average, although decreasing in
all regions relative to January (Table T2).
The Niņo-4 region was the warmest, with a value of +0.7°C for
January. Positive subsurface temperature
anomalies (averaged across 180°-100°W) increased in the last couple weeks, in
association with a downwelling Kelvin wave that
contributed to above-average temperatures in the central Pacific (Fig. T17). Compared to last month, the region of
enhanced equatorial convection expanded near the Date Line, while anomalies
remained weak over Indonesia (Fig. T25).
Low-level wind anomalies became westerly across the western Pacific
Ocean, while upper-level wind anomalies were mostly westerly over the eastern
Pacific (Figs. T20, T21).
The equatorial Southern Oscillation index was negative (-0.6 standard
deviations; Fig. T2).
Overall, these features are consistent with borderline, weak El Niņo
conditions.
The majority of models in the
IRI/CPC plume predict a Niņo 3.4 index of +0.5°C or greater
through at least the Northern Hemisphere spring 2019 (Figs. F1-F13). Given the recent downwelling
Kelvin wave and the forecast of westerly wind anomalies, most forecasters
expect SST anomalies in the east-central Pacific to increase slightly in the
upcoming month or so. Because forecasts
through the spring tend to be more uncertain and/or less accurate, the
predicted chance that El Niņo will persist beyond the spring is 50% or
less. In summary, weak El Niņo conditions are present and are
expected to continue through the Northern Hemisphere spring 2019 (~55%
chance).
Weekly updates of oceanic and
atmospheric conditions are available on the Climate Prediction Center homepage
(El
Niņo/La Niņa Current Conditions and Expert Discussions).