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El Nino Now Official - Now What?

By Joe D'Aleo
Monday, July 20, 2009

El Nino criteria has been met. Now the meteorological world looks to see how strong and how long this lasts. Count on CPC and other forecast centers to go for a warm winter as a result of El Nino but as we have shown, there are differences in El Ninos depending on the overall mode in the Pacific Basin (the PDO).

You can see the warm plume along the tropical easterly belt along the equator. The cross section shows the pool of warm water that has suppressed the thermocline in the eastern Pacific.

The oceans tried this last year in the early summer, but the warmth stayed in the eastern Pacific.





The cross section looked similar last July to the one this last week although it was a little colder in the central Pacific near the surface and beneath the thermoocline. 




See an animation of the ocean temperatures over the last years as the feeble El Nino attempt failed, La Nina returned and then El Nino developed here.



What’s Different?


The CDC’s Multivariate ENSO Index shows this year’s warming is stronger than last year but tracking along a similar path.




The ocean heat content east of the dateline in the tropical Pacific is also greater this year.





The ENSO models see this as a stronger event but with some hints it may peak before winter.




The PDO last year stayed quite strongly negative helping to return the La Nina. The MEI and PDO track well with each other.






This year, the PDO is tracking up with the MEI. In some other El Ninos in cold PDO modes, the PDO went to neutral or slightly positive for a few months before returning negative. What it does in the next few months will have a lot to say how far this El Nino goes and how quickly it ends. Stay tuned!