What does this mean for Atlantic hurricane season?
The demise of El Niño is bad news for those living along the hurricane-prone areas of the Atlantic coast. El Niño conditions tend to suppress Atlantic hurricane activity, as occurred in the 2006 hurricane season. It is extremely unlikely we will see a return to El Niño conditions this fall. A decay of El Niño this time of year is very rarely followed by a resurgence later in the year, and only one of the 20 or so computer models used to forecast El Niño is forecasting this to happen this year. It is much more likely that we will see a full-fledged La Niña episode develop. Indeed, La Niña may be already be well on its way--NOAA chief Conrad Lautenbacher remarked in a press release today, "we're seeing a shift to the La Nina, it's clearly in the data". He was refering to a large pool of cooler than normal waters that has developed in recent weeks in the sub-surface waters of the Equatorial Eastern Pacific. This is a prime situation for a La Niña to develop, and several of the long-range computer models are predicting La Niña conditions for the coming hurricane season (Figure 2). These models are not very reliable, however, and it is equally probable that we will see El Niño-neutral conditions--the absence of either a La Niña or El Niño--for the coming hurricane season.
La Niña conditions usually cause Atlantic hurricane seasons that are much more active than average, so El Niño-neutral conditions would probably be more welcome than a La Niña. Remember, though, that the worst hurricane season on record--the infamous Hurricane Season of 2005--occurred with El Niño-neutral conditions. I am expecting a much more active hurricane season than the mild season of 2006 as a result of this month's demise of El Niño.
http://www.wunderground.com/blog/JeffMasters/archive.html?tstamp=200702