ENSO-neutral conditions are expected to prevail
during the next 3 months.
The current patterns of anomalous ocean
temperatures and atmospheric circulation are consistent with ENSO-neutral
conditions in the tropical Pacific. Positive SST anomalies expanded eastward
during June 2006, with SST anomalies greater than +0.5C observed in most of
the equatorial Pacific between 130ºE and 140ºW (Fig.
1). As a result, positive SST anomalies were observed in both the Niño 4
and Niño 3.4 regions, while anomalies remained near zero in the eastern
equatorial Pacific (Niño 3 and Niño 1+2 regions) (Fig.
2). Low-level (850-hPa) and upper-level (200-hPa) winds over the tropical
Pacific were near average during the month. Beginning in February the
basin-wide upper ocean heat content increased, and since early April positive
anomalies have been observed (Fig. 3).
Most of the statistical and coupled models
predict slightly positive SST anomalies (ENSO-neutral to weak El Niño) in the Niño
3.4 region through the end of 2006 (Fig. 4).
These forecasts are consistent with the recent build up in
upper-ocean heat content along the equator (Fig. 3).
Since the low-level easterlies have been near average, it seems likely that
ENSO-neutral conditions will continue at least for the next three months.
However, the spread of the forecasts (ENSO-neutral to El Niño) indicates
considerable uncertainty in the outlook for late 2006 and early 2007.
This discussion is a consolidated effort of NOAA and its funded institutions.