Current ENSO Information
ENSO Update
18 December 2003
Summary
Overall conditions in the tropical Pacific are mostly above
average, although not strongly enough to qualify as El Nino
conditions. Based on the latest observations and forecasts, while
chances of El Nino are slightly above their average, it is most likely
that near-neutral conditions will continue through the remainder of
2003
and into the first half of 2004.
General Discussion
Warmer than average, but ENSO-neutral, conditions
are currently observed in the equatorial
Pacific, with ocean temperatures near to or less than one-half degree C
above average in the east-central Pacific. The below average ocean
temperatures that had developed in the east-central
and eastern equatorial Pacific between late April and early June
returned to near average by July. Currently, near to slightly above
average temperatures occupy much of the
east-central tropical Pacific, and above normal temperatures
extend from near the dateline westward.
Out of a large set of dynamical and statistical forecast
models, the
majority predict near-average to slightly warmer than average sea
surface temperatures to continue. (Note
1). Overall, based on model forecasts and current observations of
the
ocean surface and subsurface, the chance for development of La
Niña conditions is believed to be less than
that of an average
year (i.e. less than 25%). The chance for El Niño developement
is slightly greater than that of an average year from February 2004
through northern summer, but still less than 50%. The chance for
neutral
conditions remains equal to or greater
than that of an average year (equal to or greater than 50%) into
mid-2004.
In summary, current observations and model forecasts
suggest
that ocean
conditions will most likely remain near neutral during the remainder of
2003 and into the first half of 2004.
Note 1 - Only models
that
produce a
new ENSO forecast every month are included in the above statement.
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