El Niño on its way out – to be replaced by….?

The strong El Niño that we heard so much about over the past several months is beginning to weaken (has been for a few weeks) and will soon be just a faded memory.

Current data and computer model forecasts overwhelmingly favor the continued demise of the current El Niño which was one of the strongest on record. Once this happens, what will replace it? The answer to that question is not as clear but has possible huge implications on the upcoming hurricane season for the Atlantic.

First, a quick re-cap of what El Niño is.

Current look at SST anomalies across the tropical Pacific and the tropical Atlantic

Current look at SST anomalies across the tropical Pacific and the tropical Atlantic

The easiest way to understand the El Niño phenomenon is to think of an abnormal warming of the Pacific along the Equatorial region – usually extending from the coast of South America (where El Niño gets its namesake) westward in to the tropical Pacific. How far west and how much warming then determines the extent of the effects from said event. In the case of the current El Niño, some areas peaked out at roughly 3.0 degrees C above average – quite a significant deviation from normal.

Now things are changing. The warm episode is fading as much colder water in the subsurface continues to gather in the west Pacific, slowly moving eastward and closer to the surface. Once the trade winds return to normal across the region, this cold water will have a chance to over take the El Niño and finish it off for good. It’s just a matter of time.

Latest subsurface analysis showing the growing pool of cold water in the western Pacific

Latest subsurface analysis showing the growing pool of cold water in the western Pacific

As you can see by the computer model chart, the signal is very strong that El Niño will be gone by summer. How far gone and whether or not the Pacific does in fact swing the other way remains in question but most of the reliable long-term guidance at least suggests the possibility of La Niña conditions setting in by fall. Why does this matter? Hurricanes, that’s why.

We should all know by now that El Niño typically equals a quieter, less intense Atlantic hurricane season. This is due to strong wind shear generated across the deep tropics and other factors that act to kill off developing storms before they can get too strong. This doesn’t mean everyone is safe during an El Niño but the intense hurricanes on the Atlantic side are often kept at bay.

Latest IRI/CPC model output chart which clearly shows the demis of the current El Nino

Latest IRI/CPC model output chart which clearly shows the demise of the current El Nino

Conversely, La Niña presents us with the opposite effect. Shear is typically very low across the deep tropics and tropical seedlings have a much better chance of becoming strong hurricanes at some point. It should be pointed out that La Niña does not necessarily mean someone will get hit by a nasty hurricane. On the whole, La Niña tends to have more dreaded landfalls and so it tends to stick out more – especially compared to warm events or El Niño.

Looking at the average of the dynamic models, it would appear that El Niño is on its way out and could be replaced by La Niña conditions by late summer early fall – just in time for peak hurricane season in the Atlantic.

It wouldn’t be fair to not mention that there are other large-scale factors than can shape a hurricane season. The mere absence of El Niño can certainly change things and allow for more development but it is just one piece of the overall puzzle – a large piece, but not the only one.

Water temps off the coast of Africa have warmed considerably in recent weeks, something that will need to be monitored closely as we get in to the Atlantic hurricane season

Water temps off the coast of Africa have warmed considerably in recent weeks, something that will need to be monitored closely as we get in to the Atlantic hurricane season

Atlantic sea surface temperatures will also be a huge factor and right now, especially off the coast of Africa, those temps are running above the long term average. This can change, heck, it’s only February, but these are the puzzle pieces we keep an eye on in the off-season.

By mid-April, we will get a solid look at what to expect as Dr. Phil Klotzbach and his team from Colorado State University issue the first quantitative forecast for the Atlantic Basin. I can assure you that the state of the Pacific – whether it be El Niño or La Niña – will weigh heavily in to his predictions. Once we get to June, the outlook becomes more clear and again we’ll have an update from the team at CSU.

For now, it appears that the writing is on the wall. La Niña may be coming and if so, we just might have more to track than we have in quite some time.

I’ll have more on this topic in a few weeks as more data and other information becomes available.

M. Sudduth 12:55 pm ET February 11

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