DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP
and the International Research Institute for Climate and Society
5 September 2013
ENSO Alert System Status: Not Active
ENSO-neutral conditions persisted during August 2013, as reflected by near-average sea surface temperatures (SSTs) across much of the equatorial Pacific, with below-average SSTs in the eastern Pacific (Fig. 1). Consistent with this pattern, weekly Niño-4 and Niño-3.4 indices were between -0.5 and 0.2oC, while Niño-3 and Niño-1+2 indices were at or cooler than -0.5oC (Fig. 2). The oceanic heat content (average temperature in the upper 300m of the ocean) remained near to slightly above average during August (Fig. 3), due to the persistence of above-average sub-surface temperatures across much of the eastern half of the Pacific (Fig. 4). The low-level and upper-level winds were near average across the equatorial Pacific. Convection continued to be enhanced over Indonesia and suppressed in the central and eastern Pacific (Fig. 5). Collectively, these atmospheric and oceanic conditions reflect ENSO-neutral.
Most model forecasts continue to predict ENSO-neutral (Niño-3.4 index between -0.5oC and 0.5oC) into the Northern Hemisphere spring 2014 (Fig. 6). For the next several seasons, the average of the statistical model forecasts is near -0.5oC, while the average of the dynamical model forecasts is near or just above 0.0oC. Similar to last month, the forecast consensus favors ENSO-neutral (60% chance or greater) through December – February 2013-14 (see CPC/IRI consensus forecast).
