The collapse of El Nino in the tropical Pacific Ocean has continued throughout the spring season and it should evolve into La Nina conditions by the fall of this year. El Nino is a naturally occurring oceanic cycle that produces warmer-than-normal sea surface temperatures (SSTs) in the equatorial Pacific Ocean whereas La Nina is associated with colder-than-normal SSTs. This now fading El Nino event reached its peak intensity level during December 2015 and rivaled in intensity some of the strongest El Nino’s of the past 50 years including those of 1997-1998 and 1982-1983. El Nino had widespread consequences on weather and climate around the world including a spike in global temperatures and – if history is any guide – its demise and the eventual flip to La Nina will have important consequences as well. In fact, global temperatures have already been dropping noticeably during the past couple of months – typical of post-El Nino time periods – and should continue to do so for the foreseeable future as La Nina becomes well established.
In prior El Nino events during the past decade (e.g., 2006-2007, 2009-2010), there were indeed similar El Nino-induced spikes in global temperatures and in each of these cases temperatures dropped off sharply after La Nina conditions became established in the tropical Pacific Ocean. The plot (above) of global temperature anomalies from NOAA’s CFSR CFSv2 dataset show clearly the El Nino induced spikes back to 2005 and subsequent temperature drop offs in the post-El Nino time periods. Given the notion that once this La Nina becomes established it is likely to have some staying power, it is not unreasonable to assume global temperatures will continue to drop off going into 2017 and perhaps even beyond. As far as the Mid-Atlantic region is concerned, the transition from El Nino to La Nina usually results in hotter and drier summer weather conditions based on analog years and this idea was the foundation of the “2016 Tropical and Summer Outlook”. [Editors emphasis added]