Another update on the developing El Nino

 

This post won’t breakdown the definitions, terms, or meanings. For those you can go to my other El Nino post from earlier this year. You will find the links with in the post. This will cover the important data. It will also cover a little on how this El Nino could impact the hurricane season.

My last El Nino update can be found here

Another El Nino post can be found here

I wanted to post a quick El Nino update. There is no doubt that El Nino is in play, when we look at the Sea Surface Temperature (SST) anomalies.

 Credit: tropical tidbits

 A look at the SST and subsurface anomalies in the equatorial Pacific Ocean.

Credit: Climate Prediction Center/NCEP/NWS.

The eastern and central equatorial Pacific stand out. But we can also see SST in large parts of the global oceans are also experiencing above average SST, The Main Development Region (MDR) in the Atlantic is seeing record warmth for this time of year.

Right now, the El Nino is considered weak, but it is developing rapidly, and is knocking on the door of a moderate El Nino.

 The four El Nino-Southern Oscillation (ENSO) mentoring regions are showing El Nino conditions.  With the central and eastern Pacific SSTs exceeding El Nino thresholds.

 

   

The three-month-average Nino-3.4 Index, the Oceanic Nino Index (ONI), was 0.5 °C for April–June 2023. In order to qualify as an official El Nino year, the ONI must be at or above the threshold for at least 5 three-month periods. In this case, El Nino conditions would need to last through at least the August–October average to qualify.

Credit: tropical tidbits

2-year history of sea surface temperatures in the Nino-3.4 region of the tropical Pacific for all events evolving into El Nino since 1950 (gray lines) and the current event (purple line). NOAA Climate.gov image based on a graph by Emily Becker and monthly Niño-3.4 index data from CPC using ERSSTv5.

 

As of July 19^th, the daily contribution to SOI calculation is at -20.38. The past month has seen the Southern Oscillation Index (SOI) shift back to neutral levels, with the 30-day SOI at +3.03 for the 30 days ending 16 July. The 90-day SOI is outside El Niño thresholds at -6.03. Sustained changes in wind, cloud and broad-scale pressure patterns towards El Nino-like patterns have not yet been observed. This means the Pacific Ocean and atmosphere have yet to become fully coupled, as occurs during El Niño events. But given the rapid SST increases both at the surface and subsurface, I do think coupling will occur sooner rather than later.

 

Credit the Queensland, Australia Government website

 The most recent IRI plume shows the models favor the El Nino to continue to strengthen, right into Winter 2023-2024.

 

Credit: International Research Institute for Climate and Society. We will likely be dealing with at least a moderate El Nino through Spring 2024.

To read about what is a super El Nino click here.

The Indian Ocean Dipole (IOD) is currently neutral. All models suggest a positive IOD is likely to develop in late winter or early spring. A positive IOD will enhance the El Nino's impact.

 The Madden–Julian Oscillation (MJO) is currently weak, but some models indicate it will strengthen in the eastern Maritime Continent or Western Pacific region over the next 14 days. Should this happen, this may contribute to El Nino development by weakening trade winds. Allowing the SST to warm even more.

 

The hurricane season…

 From a forecasting stand point, the 2023 hurricane season is going to be more challenging than usual because of conflicting signals. We have a strong El Nino developing. But we also have the SST in the Atlantic being extremely warm in many areas, which could enhance storms. As I’ve said before, we have never seen the Atlantic so warm during an El Nino. So, with both ocean basins being very warm, the battle will be around which ocean is warmer? and how will that effect atmospheric connections?

Typically, during an El Nino, we see more stable air and stronger westerly wind at upper levels of the atmosphere across the tropical Atlantic. The increase in vertical wind shear, leads to the developing tropical waves having their tops sheared, So El Nino generally suppresses Atlantic hurricane activity so fewer hurricanes than average tend to form in the Atlantic during August to October, the peak of Atlantic hurricane season.

So far, the 2023 Atlantic hurricane season, has been unusual. There have been four named storms and one unnamed storm back in February. Having named storms develop in the MDR this early is almost unheard of.  There are three main reasons for all the development in the MDR this early; one is the record warm SSTs, two is the lack of dry air out over the Atlantic, three was the general lack of vertical wind shear out over the Atlantic.

The Bermuda/Azores sub-tropical high was atypically weak during May and June, this led to less Saharan air layer dry and dusty air out over the Atlantic. The weaker subtropical low also contributed to reduced wind shear. Those warm SST in the MDR also helped reduce windshear.     

So, with the Atlantic so warm, we will likely see less overall shear than we would during a typically moderate to strong El Nino. Depending on how the MJO phases work out along with the timing of the Tropical waves, we will have the potential for tropical activity in the Atlantic, leading to average to above average numbers of tropical storms or hurricanes.  

To read more on my 2023 hurricane outlook you can go here.

This is still looking to be strong El Nino. Since El Nino’s typically become their strongest during Northern Hemisphere winter, we will likely be dealing with a strong or even super El Nino for late Fall and through Winter 2023-2024. Since this is going to be the first strong El Nino with the Atlantic Basin so warm, we’re going to learn a lot on the subject and there will undoubtedly be surprises along the way.  I will likely post another El Nino update some time in August.