What is a super El Nino?

 I and most weather outlets have been talking about the developing El Nino. I have gotten a number private and public post and comments wondering about the impacts of the developing El Nino will have on our summer weather.  I’ve seen several media outlets suggest that El Nino will cause enhanced heatwaves around the world. In my hurricane and summer outlooks I talked about El Nino. I even said this year’s El Nino will be very strong and could even become a so called Super El Nino. With all the talk about this, some of y’all are a bit worried. 

So I thought this might help clear something up.

What is El Nino? …

The ENSO is a natural phenomenon that results from the coupled interactions between the tropical Pacific and the atmosphere. The changing sea surface temperatures (SST) alter rainfall, ocean currents, and wind patterns around the globe. All of this produces a positive feedback loop, which leads to even more changes.

El Nino is linked to major changes in the atmosphere known as the Southern Oscillation (SO). El Nino’s sibling is called La Nina. Both of these are encompassed by what is called the El Nino–Southern Oscillation (ENSO).  El Nino is the warmer phase, with La Nina being the cooler phase.

El Ninos generally occurs every three to seven years or so, the surface waters of the equatorial Pacific Ocean become extremely warm from the International Dateline to the west coast of South America.

SST anomaly 2023.

There are several indices used to monitor the tropical Pacific, all of which are based on SST anomalies averaged across a given region.  Usually, the anomalies are computed relative to a base period of 30 years.  The Nino 3.4 index and the Oceanic Nino Index (ONI) are the most commonly used indices to define El Nino and La Nina events.  Other indices are used to help characterize the unique nature of each event.

 

The numbers of the Nino 1,2,3, and 4 regions correspond with the labels assigned to ship tracks that crossed these regions over the last 100 years. While humans discovered El Nino during the last 100 to 150 years, the global historical record shows that the ENSO has been around for millennia.

The Nino 1+2 region is the smallest and eastern-most of the Nino SST regions. Normally, this index tends to have the largest variance of the Nino SST indices.

The Nino 3 region used to be where SST were monitored and were used in predicting El Nino, but researchers later learned that Nino region was too far east to get a true measurement for coupled ocean-atmosphere interactions when it came to defining El Nino and La Nina events.

The Nino 3.4 is now the area thought of as representing the average equatorial SST anomalies across the Pacific. The Nino 3.4 index typically uses a 5-month running mean, and El Niño or La Nina events are defined when the Nino 3.4 SSTs exceed +/- 0.4C for a period of six months or more. This is closely linked to the ONI. The ONI uses a 3-month running mean, and to be classified as a full-fledged El Niño or La Niña, the anomalies must exceed +0.5C or -0.5C for at least five consecutive months inside Nino region 3.4.

The Nino 4 index captures SST anomalies in the central equatorial Pacific.  This region tends to have less variance than the other Nino regions.

To define the distinctive character of each El Nino or La Nina event, a combination index, called the Trans-Nino Index (TNI) is used.  The TNI is defined to be the difference in normalized SST anomalies between the Nino 1+2 and Nino 4 regions.  The TNI thus measures the gradient in SST anomalies between the central and eastern equatorial Pacific.  When the SST gradient is particularly large (say, due to very warm SST anomalies in the Nino 4 region and somewhat cooler SST anomalies in the Nino 1+2 region, this is classified as a central Pacific El Nino or sometimes called El Nino Modoki.

NOAA declares an official El Nino has developed when sea-surface temperatures in Nino region 3.4 have reached at least 0.5 degrees Celsius above average for at least a month and is expected to persist for several more months.

One important thing to remember is Every El Nino cycle is different.

OK what about this year…

Over the past three years, Nino regions 1+2 to 4 have been cooler than average. So, we’ve been in a three year La Nina, which is often called a triple dip La Nina. But that ended by March of this year , and water temperatures have quickly been getting warmer since then. So currently the ENSO is in a neutral phase. Right now, anomalies are such that we’re on the cusp of El Nino. This means El Nino very well could develop sometime this summer, and that could have impacts on our summer weather here in the Northeast, and in the upcoming hurricane season. Since El Nino and La Nina events typically exert the most influence on the late Fall and winter. It could have a big impact on winter 2023-2024.

Some models are raising the possibility later this year of an extreme, or super El Nino, that is marked by very high temperatures in the Nino 3.4 region.

OK, what is a super El Nino? …

The term super El Nino is used to describe a very strong El Nino event.

Typically, when it comes to defining an El Ninos strength, anomalies of 0.5C to 1.0C above average is considered weak, anomalies 1.0C to 1.5 above average is considered moderate, with anomalies of 1.5C to 2.0C above average considered strong. Super El Ninos feature anomaly temperatures that are greater than 2C above average.

Officially there had only been three super El Ninos – 1982 to 83, 1997 to 98, and 2015 to 16. Some meteorologist also considered the El Nino in 1972 to 1973 as an extreme event.

El Nino and a warming Planet…

Typically, during an El Nino, overall temperatures around the globe, increase. During a super El Nino there can be an even large increase.

A few years ago, Joe Bastardi posted on how Super El Nino’s seem to set a new plateau in regards to warming global temperatures. I had never thought of that idea before. I don’t know if it was Bastardi or someone else who came up with the idea; but I found it fascinating and insightful. 

When we look at the UAH global temperature chart by Roy W. Spencer, Ph.D., a research scientist at the University of Alabama, Huntsville, we see that the globe is warming. When we place the years of the Super El Nino on the chart, the plateauing stands out very clear.

A warming planet does interact and aggravate the effects of El Nino.  So, it’s certainly possible we will see 2023 break the record warm year set in the last Super El Nino in 2016.

How El Nino could impact the summer pattern…

Even though the impacts of El Nino are greater during the winter, that doesn’t mean there’re no influences during the summer.

How much impact the CONUS experiences is dependent on the strength of the El Nino event.  But generally, the CONUS sees cooler than average summer temperatures and slightly less than average precipitation in the eastern half of the country during El Nino.

Here is temperature and precipitation anomaly maps that show El Nino influence based on the strength of the El Nino.   

 

These maps don’t show the influence from a super El Nino on our temperatures for the Northeast and Middle Atlantic. So, I entered the data for the super El Nino’s of 1982 to 83, 1997 to 98, and 2015 to 16.

Because some meteorologist including me also consider the El Nino in 1972 to 1973 as a super El Nino; I’ve including that as well.

As far as the upcoming winter here in the Northeast, a super El Nino could mean overall temperatures for Dec thru Feb being well above average, with a general lack of snowfall across the region. 

The idea of a super El Nino was one of the major factors I used when I came up with my Summer Outlook, which you can find here. The super El Nino also figured into my hurricane outlook for this year; but even though El Nino’s typically led to fewer numbers of tropical cyclones in the Atlantic Basin; other factors such as all the warm water in the Atlantic, hint at higher numbers than would normally be the case during an El Nino event. If you what to look at the three-part hurricane outlook you can find it here.

 

Well, that’s it. I hope this cleared up any questions or confusion you had in regards to the likely very strong/super El Nino that looks to form this year.