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
(CFSv2) 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 from the ENSO‑CLIPER
statistical model (Knaff and Landsea
1997, Wea. Forecasting, 12, 633‑652) are shown in Fig.
F9. Niño 3.4 predictions are summarized in Fig. F10, 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 Nina Watch
Outlook: ENSO-neutral is
expected to continue for the next several months, with La Nina favored to emerge
during August-October (70% chance) and persist into the Northern Hemisphere
winter 2024-25 (79% chance during November-January).
Discussion:
ENSO-neutral continued this past month, indicated in
the mostly near average sea surface temperatures (SSTs) across the east-central
and eastern equatorial Pacific Ocean (Fig.
T18). The June Nino-3.4 index was +0.2C,
while SST anomalies remained cooler in the eastern Nino-1+2 region (-0.7C) and
warmer in the western Nino-4 region (+0.7C; Table T2). Below-average subsurface
temperatures weakened during the past month, but negative anomalies still
dominated the eastern half of the Pacific (Fig.
T17). Low-level wind anomalies were
easterly over the western equatorial Pacific, and upper-level winds were westerly
over the eastern Pacific (Figs. T20 & T21).
Convection was near average around Indonesia and the Date Line (Fig. T25).
Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral.
Compared to the previous month, the most recent IRI
plume delayed the emergence of La Nina to September-November 2024, with La Nina
then persisting through the Northern Hemisphere winter (Figs. F1-F12). The forecast team is also favoring a delayed
development of La Nina this month, but is anticipating the transition to occur
earlier (August-October). This is, in part, supported by the continuation of below-average
subsurface ocean temperatures and near-term forecasts suggesting a resurgence
of easterly wind anomalies in July. In summary, ENSO-neutral is expected to
continue for the next several months, with La Nina favored to emerge during
August-October (70% chance) and persist into the Northern Hemisphere winter
2024-25 (79% chance during November-January).
Weekly updates of oceanic and atmospheric conditions
are available on the Climate Prediction Center homepage (El
Niño/La Niña Current Conditions and Expert Discussions).