ENSO-neutral is favored into the
late Northern Hemisphere summer 2013
During
April 2013, ENSO-neutral continued, with near-average sea
surface temperatures (SSTs) observed across most of the
equatorial Pacific Ocean, and below average SSTs confined to the
far eastern equatorial Pacific (Fig.
1). The Niño indices were near zero throughout the month,
except for the Niño1+2 region which was between -1.2oC
and -0.5oC (Fig.
2). The oceanic heat content (average temperature in the
upper 300m of the ocean) remained near average during April (Fig.
3), reflecting near-average subsurface temperatures at depth
across most of the central and eastern equatorial Pacific (Fig.
4). The tropical low-level easterly winds remained slightly
enhanced over the western half of the Pacific basin, and
anomalous upper-level westerly winds prevailed across much of
the equatorial Pacific. Tropical convection was enhanced over
Indonesia and the western Pacific and suppressed over the
central Pacific (Fig.
5). Collectively, these conditions indicate the continuation
of ENSO-neutral.
Most
models forecast Niño-3.4 SSTs to remain ENSO-neutral into the
Northern Hemisphere winter (Fig.
6), with dynamical models tending to predict warmer
conditions (-0.3oC to 0.4oC) than the
statistical models (-0.7oC to 0oC). There
is still low confidence in the forecasts for the latter half of
the year, partly because of the so-called “spring barrier,”
which historically leads to lower model skill for forecasts made
between March and May. Forecast confidence will increase over
the next few months. The current forecast indicates that
ENSO-neutral will likely continue into the second half of 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
Niño/La Niña Current Conditions and Expert Discussions).
Forecasts for the evolution of El Niño/La Niña are updated
monthly in the
Forecast Forum section of CPC's Climate Diagnostics
Bulletin. The next ENSO Diagnostics Discussion is scheduled for
6 June 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.
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