La Niņa is favored to develop (~70% chance)
during the Northern Hemisphere fall 2016 and slightly favored to
persist (~55% chance) during winter 2016-17.
ENSO-Neutral conditions were observed during September, with negative
sea surface temperatures (SSTs) anomalies expanding across the eastern
equatorial Pacific Ocean by early October
(Fig. 1). All of the Niņo regions cooled considerably during late
September and early October, with the latest weekly value of Niņo-3.4
index at -0.9°C
(Fig. 2). Subsurface temperature anomalies also decreased toward the
end of the month
(Fig. 3), reflecting the strengthening of below-average temperatures
at depth in the east-central equatorial Pacific
(Fig. 4). Atmospheric anomalies across the equatorial Pacific edged
toward La Niņa during September, with a stronger tendency toward La Niņa
late in the month. The traditional Southern Oscillation index and the
equatorial Southern Oscillation index were positive. The lower-level
winds were near average across most of the basin during the month, but
enhanced easterlies were becoming more persistent west of the
International Date Line. Upper-level winds were anomalously westerly
near and just east of the International Date Line. Convection was weakly
suppressed over the central tropical Pacific and was more enhanced over
Indonesia compared to last month
(Fig. 5). Overall, the combined ocean and atmosphere system reflects
ENSO-Neutral during September, but are more clearly trending toward La
Niņa conditions.
The multi-model averages favor borderline Neutral-La Niņa conditions
(3-month average Niņo-3.4 index less than or equal to -0.5°C) persisting
during the Northern Hemisphere fall and continuing into the winter
(Figs.
6 and
7). Because of the recent cooling in the Niņo-3.4 region and signs
of renewed atmospheric coupling, the forecaster consensus now favors the
formation of a weak La Niņa in the near term, becoming less confident
that La Niņa will persist through the winter. In summary, La Niņa is
favored to develop (~70% chance) during the Northern Hemisphere fall
2016 and slightly favored to persist (~55%% chance) during winter
2016-17 (click
CPC/IRI consensus forecast for the chance of each outcome for each
3-month period).period).
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
are also updated monthly in the
Forecast Forum of CPC's Climate Diagnostics Bulletin. Additional
perspectives and analysis are also available in an
ENSO blog.
The next ENSO Diagnostics Discussion is scheduled for 10 November 2016 .
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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