ENSO-neutral is favored through the Northern Hemisphere summer 2013
During May 2013, ENSO-neutral continued, as reflected by the persistence
of near-average sea surface temperatures (SSTs) across much of the
equatorial Pacific Ocean (Fig.
1). However, below average SSTs in the eastern Pacific strengthened,
with the weekly index values in the easternmost Niņo-3 and Niņo-1+2
regions near or less than -1.0oC by the end of month (Fig.
2). The weekly Niņo-3.4 and Niņo-4 regions remained greater than
-0.5oC through May. The oceanic heat content (average temperature in the
upper 300m of the ocean) was near average, but decreased slightly (Fig.
3) due to the emergence of below-average sub-surface temperatures in
the eastern Pacific (Fig.
4). Across the Pacific, equatorial winds remained near average,
except for weak low-level easterly anomalies in the western Pacific and
weak upper-level westerly anomalies in the western and central Pacific.
Tropical convection remained enhanced over Indonesia and suppressed over
the central Pacific (Fig.
5). Despite a tendency toward cooler conditions, the overall state
of the tropical Pacific was consistent with ENSO-neutral.
The majority of the model forecasts favor the continuation of
ENSO-neutral, with most models predicting Niņo-3.4 index values below
zero (Fig.
6). A smaller number of models (mainly statistical) predict weak La
Niņa conditions (Niņo-3.4 less than
-0.5oC) as soon as the Northern Hemisphere summer. As a result, the
forecast consensus indicates larger chances for La Niņa relative to El
Niņo, but there still remains close to a 60% or greater chance of
ENSO-neutral through the Northern Hemisphere summer 2013 (see
CPC/IRI consensus forecast).
This discussion is a consolidated effort of the National Oceanic and
Atmospheric Administration (NOAA), NOAA's National Weather Service, and
their funded institutions. Oceanic and atmospheric conditions are
updated weekly on the Climate Prediction Center web site (El
Niņo/La Niņa Current Conditions and Expert Discussions). Forecasts
for the evolution of El Niņo/La Niņa are updated monthly in the
Forecast Forum section of CPC's Climate Diagnostics Bulletin. The
next ENSO Diagnostics Discussion is scheduled for 5 July 2013. To
receive an e-mail notification when the monthly ENSO Diagnostic
Discussions are released, please send an e-mail message to:
ncep.list.enso-update@noaa.gov.
Climate Prediction Center
National Centers for Environmental Prediction
NOAA/National Weather Service
College Park, MD 20740
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