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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 skill.
Outlook
A transition from ENSO-neutral
to La Niña conditions is possible during the next 3 months.
Discussion
The pattern of anomalous sea surface temperatures (SSTs) during March 2007 is
consistent with ENSO-neutral conditions in the tropical Pacific, with average
to below-average SSTs extending from the date line to the west coast of
South America
(Fig. T18).
Positive anomalies greater than +0.5ºC along the equator were
restricted to the region between 145ºE and the date line (180º).
The latest weekly SST departures were near 0ºC in the Niño 3.4
region, and below -0.5ºC in the Niño 3 and Niño 1+2 regions.
The equatorial upper-ocean heat content (average temperature departures in
the upper 300 m of the ocean) remains below-average across the central and
east-central equatorial Pacific, as the upper ocean continued to cool and
negative temperature anomalies persisted (Fig. T15).
Consistent with the surface and sub-surface temperature patterns,
stronger than-average low-level easterly winds continued throughout the month
over the central equatorial Pacific (Figs. T7
and T20), and convection was enhanced over
the western equatorial Pacific and
Indonesia
and suppressed to the east of the date line (Fig. T25).
Collectively, these atmospheric and oceanic conditions are consistent with a
trend towards a Pacific cold episode (La Niña).The value of the Oceanic Niño Index (ONI;
3-month running mean average of SST anomalies in the Niño 3.4 region –
computed using the Extended Reconstructed SST version-2 data set) for January
– March 2007 is +0.3°C,
which reflects ENSO-neutral conditions in the tropical Pacific. Most
of the statistical and coupled models, including the NCEP Climate Forecast
System (CFS), indicate additional anomalous cooling during the next several
months (Figs. F1,
F2, F3, F4a,
F4b, F5, F6,
F7, F8, F9,
F10, F11, F12
and F13). This forecast is consistent with the observed trends in
atmospheric and oceanic conditions towards a Pacific cold episode. However,
the spread of the most recent statistical and coupled model forecasts (ENSO-neutral
to La Niña) indicates considerable uncertainty as to when La Niña might
develop and how strong it might be.
Weekly
updates of SST, 850-hPa wind, OLR and features of the equatorial subsurface
thermal structure are available on the
Climate
Prediction
Center homepage at:
http://www.cpc.ncep.noaa.gov/
|
www.nws.noaa.gov
