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 ENSO‑CLIPER
statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652)
are shown in Fig. F11. Niño 3.4
predictions are summarized in Fig. F12, 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: La Niña Advisory
Outlook:
La
Niña is likely to continue through the Northern Hemisphere winter 2020-21 (~95%
chance during January-March), with a potential transition during the spring
2021 (~50% chance of Neutral during April-June).
Discussion:
La
Niña persisted during November, as indicated by well below-average sea surface
temperatures (SSTs) extending from the Date Line to the eastern Pacific Ocean (Fig. T18). Most of the monthly Niño indices decreased
slightly in the past month, with Niño-3.4 ending up at -1.3ºC (Table T2).
The negative equatorial subsurface temperature anomalies (averaged from
180°-100°W) weakened slightly last month, but continued to reflect
below-average temperatures from the surface to 200m depth in the eastern
Pacific Ocean (Fig. T17).
The atmospheric circulation over the tropical Pacific Ocean remained
consistent with La Niña. Over the
western and central tropical Pacific Ocean, low-level wind anomalies were
easterly and upper-level wind anomalies were westerly (Fig. T20 & Fig. T21). Tropical convection continued to
be suppressed from the western Pacific to the Date Line (Fig. T25). Also, both the Southern Oscillation and
Equatorial Southern Oscillation indices were positive (Table T1 & Fig. T2).
Overall, the coupled ocean-atmosphere system indicates the continuation
of La Niña.
A
majority of the models in the IRI/CPC plume predict La Niña (Niño-3.4 index
less than -0.5°C) to persist through the Northern Hemisphere winter 2020-21 and
to weaken through the spring (Figs. F1-F12). Supported by the latest forecasts from several
models, the forecaster consensus is for a moderate strength La Niña (Niño-3.4
index values between -1.0ºC and -1.5ºC) during the peak November-January
season. In summary, La Niña is likely
to continue through the Northern Hemisphere winter 2020-21 (~95% chance for
January-March), with a potential transition during the spring 2021 (~50% chance
of Neutral during Apr-Jun).
Weekly
updates of oceanic and atmospheric conditions are available on the Climate Prediction
Center homepage (El
Niño/La Niña Current Conditions and Expert Discussions).