The surface water of the Equatorial Pacific is showing signs of becoming warmer than average, which would indicate a transition to El Niño conditions. That region has remained "neutral" through May, but temperatures have been gradually rising for five months. By the end of May, sea surface temperatures were about +0.4° to +0.5°C in the critical region, which suggest the beginning of an El Niño. Read the entire ENSO Discussion.
Based on these recent trends, it is likely that the Equatorial Pacific will transition to El Niño conditions from June through August 2009. Read the latest weekly update here.
Our most recent ENSO episode was a La Niña from August 2007 to June of 2008. Since then, we have been in weak La Niña transitioning to neutral conditions through 2009 so far.
The last El Niño episode was July 2006 through February 2007.
What could El Niño mean for the Commonwealth? Well, not much. For a Summertime El Niño episode, not much deviation from average is documented for Virginia. In fact in the United States, only the Rocky Mountain West shows any substantial response in the Summer to an El Niño with wetter than average conditions. The U.S. tends to experience more noticeable climate impacts during a Winter El Niño event.
(Click to enlarge this graphic)
Well, what about impacts from El Niño on the Atlantic Hurricane Season? Research has shown that El Niño's wind profiles encourage the development of more eastern Pacific hurricanes, while hindering the development of Atlantic hurricanes. La Niña leads to the opposite, with fewer eastern Pacific hurricanes and more Atlantic hurricanes. Read here for a full discussion on ENSO's possible impact on tropical activity. So this means that the chances for the Atlantic and Gulf Coasts to receive a hurricane are reduced. However, this does not mean that hurricanes cannot form and do significant damage during an El Niño season.
--Carrie
