What may be in store for the fall and winter? Overall, most of the computer models we consult predict that the sea surface temperature in the Nino3.4 region will remain near average through the fall and into the winter. Now go away or I shall taunt you a second time Once the surface temperatures return to average, and the source of extra heat to the air above the central Pacific is gone, the atmospheric component of El Niño-that weakened Walker circulation-will also return to average. This is one of the major factors in our forecast for a return to near-average surface temperatures and neutral ENSO conditions. Overall, the heat content in the top 300 meters of the equatorial Pacific is just about average now, in early July. This cross-section is right along the equator. The vertical axis is depth below the surface (meters) and the horizontal axis is longitude, from the western to eastern tropical Pacific. In early June, there was a small downwelling Kelvin wave of warmer waters moving eastward under the surface of the Pacific, but this wave has dissipated recently.ĭeparture from average of the surface and subsurface tropical Pacific sea temperature averaged over 5-day periods starting in early June 2019. This can tell us if there is a source of warmer-than-average water to supply the surface, continuing to fuel El Niño, or not. That’s no ordinary rabbitĪs frequent readers of this blog will know, we closely monitor the temperature of the water under the surface of the tropical Pacific. All in all, El Niño is still present, but just barely. But the upper-level and near-surface winds over the equatorial Pacific, another component of the Walker circulation, were close to average during June. The Southern Oscillation Index and Equatorial Southern Oscillation Index were both slightly negative in June, also indicating some continuation of the weakened Walker circulation we expect to see with El Niño. There is some evidence that the atmosphere over the central Pacific is still responding to that extra heating, as a bit more clouds and rain than average were present in June. The June Niño3.4 index, our primary ENSO measurement, was 0.6☌ above the long-term average, just above the El Niño threshold of 0.5☌. Neutral conditions are favored to remain through the fall and winter. It’s likely that the temperature of the tropical Pacific Ocean surface will return to near-average soon, qualifying for “ENSO-neutral” conditions. El Niño is hanging on by its fingernails, but forecasters predict this event will wind down within the next couple of months.
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