There is a 58% chance of El Niņo
during the Northern Hemisphere winter, which is favored to last
into the Northern Hemisphere spring 2015.
During
October 2014, above-average sea surface temperatures (SST)
increased slightly across the eastern half of the equatorial
Pacific (Fig.
1). The weekly Niņo indices were between +0.6oC
(Niņo-3.4 and Niņo-1+2) and +0.9oC (Niņo-3) at the
end of the month (Fig.
2). Subsurface heat content anomalies (averaged between 180o-100oW)
were largely unchanged (Fig.
3) even as a new downwelling Kelvin wave increased
temperatures at depth in the central Pacific (Fig.
4). The monthly equatorial low-level winds were near
average, although anomalous westerlies continued to emerge on
occasion. Upper-level winds were also mostly average across the
Pacific. The Southern Oscillation Index continued to be
negative, accompanied by mostly average rainfall near the Date
Line and suppressed rainfall over Indonesia (Fig.
5). Overall, several features across the tropical Pacific
are characteristic of borderline El Niņo conditions, but
collectively, the combined atmosphere and oceanic state remains
ENSO-neutral.
Similar to
last month, most models predict El Niņo to develop during
October-December 2014 and to continue into early 2015 (Fig.
6). However, the ongoing lack of clear atmosphere-ocean
coupling and the latest NCEP CFSv2 model forecast (Fig.
7) have reduced confidence that El Niņo will fully
materialize (at least five overlapping consecutive 3-month
values of the Niņo-3.4 index at or greater than 0.5oC).
If El Niņo does emerge, the forecaster consensus favors a weak
event. In summary, there is a 58% chance of El Niņo during the
Northern Hemisphere winter, which is favored to last into the
Northern Hemisphere spring 2015 (click
CPC/IRI consensus forecast for the chance of each outcome).
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
6 November 2014. 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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