NOAA: El Niño expected to strengthen and last through the Northern Hemisphere winter
NOAA’s National Weather Service Climate Prediction Center released its monthly El Niño/Southern oscillation (ENSO) Diagnostic Discussion:
A weak El Niño continued during August 2009, as sea surface temperature (SST) remained above-average across the equatorial Pacific Ocean (Fig. 1). Consistent with this warmth, the latest weekly values of the Niño-region SST indices were between +0.7°C to +1.0°C (Fig. 2). Subsurface oceanic heat content anomalies continued to reflect a deep layer of anomalous warmth between the ocean surface and the thermocline, particularly in the central Pacific. Enhanced convection over the western and central Pacific abated during the month, but the pattern of suppressed convection strengthened over Indonesia. Low-level westerly wind anomalies continued to become better established over parts of the equatorial Pacific Ocean. These oceanic and atmospheric anomalies reflect an ongoing weak El Niño.
A majority of the model forecasts for the Niño-3.4 SST index suggest El Niño will reach at least moderate strength during the Northern Hemisphere fall (3-month Niño-3.4 SST index of +1.0°C or greater). Many model forecasts even suggest a strong El Niño (3-month Niño-3.4 SST index in excess of +1.5°C) during the fall and winter, but current observations and trends indicate that El Niño will most likely peak at moderate strength. Therefore, current conditions, trends, and model forecasts favor the continued development of a weak-to-moderate strength El Niño into the Northern Hemisphere fall 2009, with the likelihood of at least a moderate strength El Niño during the winter 2009-10.
This should be enough to drive us to record temperatures, but there is typically a few month delay between an El Niño and the full global temperature impact. So if this is only a moderate El Niño but it lasts through the winter, then it may be 2010 that is the record. For more details on the implications, see here.