|
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
ENSO-neutral conditions are
expected to continue for the next one to three months, with a 50%
chance that weak warm episode (El Niño) conditions will develop by the end
of 2006.
Discussion
The atmospheric circulation and precipitation patterns during July 2006 were
consistent with ENSO-neutral conditions in the tropical Pacific. However,
equatorial surface and subsurface temperature anomalies increased during the
month, with SST anomalies greater than +0.5ºC observed in most of the
equatorial Pacific between 130ºE and 140ºW (Fig. T18).
As a result, positive SST anomalies were observed in all of the Niño
regions (Table T2 and Fig. T5).
During July, low-level (850-hPa)
easterly winds were weaker than average across most
of the equatorial Pacific (Fig. T 20),
and the Southern Oscillation Index (SOI) was negative for the third
consecutive month (Fig. T1).
Beginning
in February the basin-wide upper ocean heat content increased, and since
early April positive anomalies have been observed. Positive
upper-ocean heat content anomalies are usually a precursor to warm (El Niño)
episodes.
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 May -
July 2006 is 0.1°C, which
indicates ENSO neutral conditions. The
statistical and coupled model forecasts range from ENSO-neutral to weak warm
(El Niño) episode conditions for the
remainder of 2006 and into early 2007 (Figs. F1,
F2, F3, F4a,
F4b, F5, F6,
F7, F8, F9,
F10, F11, F12
and F13).
The
forecasts are consistent with the recent build up in upper-ocean heat content
along the equator, indicating a trend toward warm-episode conditions.
In the absence of any strong intraseasonal (Madden-Julian Oscillation
– MJO) activity, a continued slow trend toward warm-episode conditions is
expected. Therefore, ENSO-neutral
conditions are expected to continue for the next one to three months, with
a 50% chance that weak warm episode (El Niño) conditions will develop by the
end of 2006.
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
