El Niño not likely to be a factor for 2015 Atlantic hurricane season

Even though it is January, there are clues that we can look for when trying to figure out how busy the upcoming Atlantic hurricane season may be. One of those clues is the state of the El Niño.

As we know, El Niño or the abnormal warming of the tropical Pacific, tends to suppress Atlantic hurricane activity due to a number of factors. For a good deal of 2014, it looked as though a rather substantial El Niño event was going to unfold – it failed to do so. However, the tropical Pacific did warm quite a bit and in fact, most of the warmest water on the globe was found in the Pacific during last year’s hurricane season. This is a big reason why the east Pacific was so very busy and the Atlantic was not.

As of early January, the tropical Pacific was only slightly warmer than usual with a noticeable decline in sea surface temperatures in the east Pacific, just west of Central America. In fact, as far as I can tell, we are not even in an official El Niño right now as the thresholds have not been met. This is not surprising if we look at some other aspects of a traditional El Niño event.

One of those aspects is the SOI or Southern Oscillation Index. Typically the more negative it is, the more likely we are to see El Niño conditions prevail in the atmosphere AND in the oceans. What’s the trend over the past 90 days been? A slow and steady rise in the SOI. As the chart shows, October was -8.2, November was -8.0 and December was -7.6 with the current daily value showing +4.4. What does this mean? In short, it means that the pressure pattern is such that the trade winds are not all that weak across the tropical Pacific and thus the El Niño is being held back if not stopped completely.

Latest SOI chart from the Australian BOM

Latest SOI chart from the Australian BOM (click to view full size)

More evidence of the collapse of the El Niño can be seen via the temperature depth anomaly chart from the Climate Prediction Center. This shows us what the temperature profile is of the tropical Pacific from the surface down several hundred meters. Clearly you can see the loss of the warm pool as the animation progresses over the past several weeks. In fact, cooler anomalies are showing up in the eastern Pacific at a depth of around 110-150 meters. Unless more warm water begins to migrate eastward (from left to right on the chart) then the warming of the tropical Pacific will be very slow if not stopped entirely.

Equatorial Pacific Temperature Depth Anomaly Animation

Equatorial Pacific Temperature Depth Anomaly Animation (click to view full size)

So what does this all mean as far as impact on the 2015 hurricane season? While it’s too early to be confident about the demise of the El Niño, the most recent forecasts indicate that the odds of neutral conditions are beginning to outweigh El Niño as we get in to the Atlantic hurricane season which begins in June. This is very important because a cooler tropical Pacific would likely mean less upward motion in that region compared to what we saw in 2014 and this could lead to a better chance for Atlantic development, even if only a little. Remember, 2014 was not too far off from being an average season and so any increase in activity this year would seem to most people as being quite busy, especially considering how slack things have appeared to be since 2012.

Early January 2015 forecast for ENSO state - notice how the green (neutral) outweighs the red (El Nino) beginning as soon as the Feb/Mar/April time frame

Early January 2015 forecast for ENSO state – notice how the green (neutral) outweighs the red (El Nino) beginning as soon as the Feb/Mar/April time frame (click for full size image)

There are many other factors to consider as we enter the 2015 Atlantic hurricane season but the state of the ENSO is a big one and thus far, it appears that it will not be much of a negative influence. Obviously, the climate models can and do make gross miscalculations and we could end up with a raging warm episode by late summer. However, with other signals leaning in the direction of a non-El Nino event shaping up, I tend to think that the forecast will be pretty accurate and that we will not have an El Nino during the 2015 hurricane season. We shall see…

I will post an update to this information in early April, right before the National Tropical Weather Conference which is being held in South Padre Island again this year. By then, we’ll be within 90 days of the hurricane season getting started. I’ll have other topics posted before April of course but that’s the next logical time to take a look at the ENSO state again. Until next time, stay warm!

M. Sudduth 9:26 AM ET Jan 14

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How’s that El Niño coming along?

Remember back in the spring when it looked like we might have a super-jacked-up El Niño? Well, that didn’t work out as some had thought, or hoped, but it does finally look as though El Niño is upon us.

Warm tropical Pacific, as seen by the orange and red plume spreading west from South America, indicates El Nino is all but here.

Warm tropical Pacific, as seen by the orange and red plume spreading west from South America, indicates El Nino is all but here.

First of all, what exactly is an El Niño? In short, it is an abnormal warming of the tropical Pacific, roughly near the Equator. As trade winds weaken, or sometimes even reverse, warmer water is able to establish itself in a band stretching from South America westward for more than two thousand miles in to the tropical Pacific. The result is often a tumultuous set of weather patterns that are thrown in to disarray due to the warmer than normal area of water.

For the Atlantic Basin hurricane season, El Niño usually equates to fewer and less intense hurricanes. It looks as though the growing warm event did not have much impact on the 2014 season directly although some of the atmospheric conditions that were present can be linked to El Niño-like patterns. An example would be the abnormally high upper level wind shear across the Caribbean and most of the tropical Atlantic this season. That is typical of El Niño despite the fact that we were not technically experiencing El Niño conditions for most of the season. In any case, it looks as though the real deal is coming on now and will be with us for the next several months at least.

Current ENSO forecast from CPC/IRI - 11/20/14

Current ENSO forecast from CPC/IRI – 11/20/14

According to the latest updates coming out of various meteorological agencies around the world, we are very close to officially having an El Niño event take place. Typically sea surface temperatures across a certain region of the Pacific need to exceed .50 degrees Celsius above the norm for an El Niño to be declared. This also needs to span a specific amount of time, not just a few days or weeks. The latest calculation from the Climate Prediction Center indicates a sea surface temperature anomaly of .80 degrees Celsius, .30 above the minimal threshold. It won’t be long now and the 2014/15 El Niño will be official.

Aside from the usual fun and games that come with El Niño for winter and spring in the Northern Hemisphere, I like to look and see what the outlook is for the coming hurricane season. It is not typical for an El Niño to last for more than a year, it usually peaks in the early spring once the onset is official and slowly fades out during the summer and fall.

So far, it looks like we will see El Niño conditions prevail through at least the next three to six months. Computer model forecasts for El Niño are notoriously bad for long lead times. After all, many were calling for anomalies exceeding 2.0 degrees Celsius by now which would be an exceptionally strong event. Obviously we are nowhere near that mark and the models that were predicting such drastic increases in ocean temperatures were flat out wrong.

One aspect of this El Niño event that I am watching closely is how well it performs at seeding the tropics with more moisture. I believe that the cooler than average Pacific over the past several years, until this year really, has helped to dry out the tropics somewhat. This might explain to some degree why the Atlantic Basin has been fairly inactive hurricane-wise after the busy 2012 season. Now that El Niño is coming on, more moisture will be fed in to the tropical atmosphere over thousands of miles which should, in turn, spread around the globe, increasing moisture and thus vertical instability in the tropics. We saw this already with the very busy east Pacific hurricane season. It is my theory that El Niño may help to jump-start tropical cyclone activity world-wide starting in 2015. This may be especially true if in fact the warm event fades as it should do starting in the spring and early summer. We will be left with added moisture in the deep tropics combined with gradually cooling tropical Pacific waters. The result, in my opinion, should be an increase in Atlantic hurricanes beginning in 2015, probably spanning a few years after. We shall see. Even if 2015’s hurricane season is more busy than the past two, it won’t necessarily mean that I was correct. I just think that the simple fact that cool water does not lead to as much evaporation and thus moisture in the atmosphere helps to explain, even if only a little, why the global numbers of tropical cyclones have been down in recent years.

For now, El Niño seems almost a certainty. How strong the event is and how long it lasts will certainly shape not only the winter and spring weather patterns but also next year’s Atlantic hurricane season. It is just one piece of the puzzle and it’s a fairly large one at that.

For more in-depth information on the latest thinking from the International Research Institute, check out this link: IRI Technical ENSO Update Published: November 20, 2014

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Tropical wave in cental Atlantic a sign of what’s ahead

Tropical Weather Outlook map from the NHC showing area of interest in the central Atlantic

Tropical Weather Outlook map from the NHC showing area of interest in the central Atlantic

Not much going on in the tropics since Arthur earlier this month. This is typical for July which is usually a very quiet month in the Atlantic Basin.

In fact, we did not have any tropical waves to flare up worth mentioning until yesterday when the NHC issued an outlook for one in the central Atlantic. It rolled off of Africa a few days ago and has a low pressure area associated with it at the surface. Water temps are warm and overall, environmental conditions are generally favorable for development right now. However, this is likely only temporary as it looks as though conditions will not be so great for development as the week wears on. It’s just too early in the season yet for robust Cape Verde tropical waves to get going this far east. We’re still looking at another month or so before that happens.

The presence of this system does remind us of what could lie ahead. As I mentioned, July is usually not very active, especially in the deep tropics. Once we get in to mid to late August, conditions change and we begin to see more and more active tropical waves moving west from Africa. At that point, it will come down to upper level winds and, perhaps more importantly, instability in the atmosphere. If the mid-levels of the atmosphere are too dry with lower humidity value than usual, then the tropical waves will struggle to develop deep convection and will remain weak. On the other hand, if moisture levels are where they should be or are above average, then we would likely see a very busy August and September.

I believe that much will depend on the situation with the El Nino which was forecast to be coming on quite strong by August. As it turns out, there is barely any El Nino to talk about, especially in the central regions of the tropical Pacific. It just never made it and what warming there was has all but vanished. However, the water just west of South America, extending westward for several hundred miles, is still quite warm compared to normal. This could have just enough negative influence on the Atlantic side to help keep the peak months of August-October quieter than normal.

One thing I will be watching for is how much, if any, cooling takes place in this region of the Pacific. There are indications that we could see a considerable drop off in the surface temperatures of this area and if this happens, I suppose it could remove at least a portion of the negative influence for the Atlantic Basin. It’s just so complicated and hard to tell if one puzzle piece really makes that big of a difference considering how the other pieces fit together and interact with each other.

For me, the tropical wave that the NHC is talking about this morning is a sign that we are approaching the peak months of August-October. Thus it is a good time to remind you to be aware and prepared. Arthur was an interesting event in that it was so early in the season and it did not fall apart at landfall – instead, it continued to strengthen despite its close proximity to the North Carolina coast. If that is the way things will go this season, it won’t matter much if tropical waves develop far out in the Atlantic. What matters are the ones that would do so close to land, leaving little time to react. We’ll see how things shape up over the coming weeks but August is just around the corner and from there on, at least from a climatological perspective, the season should become more active. Time will tell just how active, that is the only certainty at this point.

I’ll have another blog post here tomorrow morning.

M. Sudduth 10:24 AM ET July 21

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El Niño or El Nada?

Well, well, well. Look at what we have here. Yet another substantial El Niño forecast, by some, that is not likely to come to pass. There was talk earlier in the year that an ENSO (El Niño Southern Oscillation) event that could rival the 1997 “Super El Niño” was in the making. Finally, we had a new buzzword to supplant “Polar Vortex” and my how people ran with it. The prospects of a record-breaking El Niño seemed destined for the history books. I have to admit, the evidence seemed to support the possibility but then something happened, something quite simple: It didn’t happen.

Actually, it is much more complicated than that but that’s the bottom line, right? There is no super-sized El Niño in the making. In fact, we may barely make it to El Niño status before the year is out. But forecasters seemed so sure. What happened? For what ever reason, the atmosphere and the ocean failed to get married. They had a nice engagement but it was not meant to be. So we see parts of the Equatorial Pacific beginning to cool and the subsurface, that’s where the real story is. Let’s take a look.

Subsurface anomalies dated April 23, 2014

Subsurface anomalies dated April 23, 2014

Here is a subsurface analysis from April 23 that showed a large pool of very warm water compared to average. This warm pool was headed east and set off many people thinking that THIS was IT! Super El Niño was coming! You have to admit, that is one large area of positive anomalies but look west (the left side of the graphic). Even by April 23 it was obvious (to me anyway) that there were no reinforcements! I thought surely this warm pool would be followed by another one, maybe even stronger. Nope. None came.

Subsurface anomalies dated June 22

Subsurface anomalies dated June 22

In fact, as you can see in the second graphic, which is the most recent analysis, not only did the warm pool not get a reinforcing shot, the existing one shrank! And, wait a minute, what’s this? COLD WATER? Yep, that is a large pool of cold anomalies that has crept in to the picture. Hard to believe that just a few months ago, we were looking at the prospects of a globally challenging ocean/weather phenomenon the likes of which we haven’t seen since 1997! Unless something completely unexpected happens over the next few months, I think it is safe to say that a minimal El Niño event is in store if we even get to that point. Those cold anomalies are really interesting since they were not forecast to be there right now.

So what does this all mean? It means that computer guidance still has a long way to go when dealing with ocean/atmosphere coupling. El Niño doesn’t just happen – a complex series of mechanisms needs to be set in to motion and remain in motion for a period of time. If one side gives up, the whole system crashes. Perhaps it wasn’t meant to be or perhaps I am wrong and a Super El Niño will put me in my place before the end of the year. It had better get going soon, we’re almost to July and after that, the peak months of the Atlantic hurricane season arrive. With no substantial El Niño in place, I have to wonder….are the forecasts for a slack hurricane season also going to bust? After all, go back and read them, most make mention of El Niño and its negative influence on Atlantic tropical cyclone activity. No El Niño, no negative influence. Naw, that’s too simple, it can’t possibly be right.

I guess we’ll see. Let’s re-visit this on November 30, shall we?

In the meantime, we will watch the Southeast coastal areas for possible development over the next few days. Some of the global computer models are trying to cook up a low pressure area over the warmer-than-normal water that is lurking in the southwest Atlantic. I’ll have more on this over the weekend.

M. Sudduth 8:30 AM ET June 27

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Polar Vortex out, El Niño in?

Cross section of subsurface water in the tropical Pacific over the past few months. Clearly, a warm pool of water has developed deep beneath the Pacific and is expanding east.

Cross section of subsurface water in the tropical Pacific over the past few months. Clearly, a warm pool of water has developed deep beneath the Pacific and is expanding east.

The much maligned term “Polar Vortex” that was used quite often this winter within the weather blogosphere is about to be replaced….maybe. By what? El Niño. Yep. The Great El Niño could be making a comeback. Remember the Saturday Night Live sketch with Chris Farley about this phenomenon? It was a classic and just another example of how weather mixing with pop culture can be fun but sometimes quite wrong.

El Niño is not a single event like a storm or a hurricane. Instead, it is just a name that us humans have assigned to a change in the tropical Pacific that results in sea surface temperatures being warmer than the long-term average. Once a certain threshold has been met, we call it El Niño. Make no mistake, it will get a lot of play in the media, especially where Global Warming is concerned. The reason? The oceans act like giant cooling or heating agents. When the Pacific, the largest water basin on the planet, is warmer than it should be, then we typically see global temperatures spike – as if someone turned up the thermostat for the earth. My bet is that the pro-global warming crowd will be salivating at the potential El Niño event as it will help to boost their notion that man is screwing things up in a big way. I have no dog in that fight as it does not matter to me. What I mean is, so what? If man is making Earth warmer, who is going to go first to completely stop living in modern times? Anyone? That’s what I thought. My take is: adapt and mitigate. If not, we perish. No debate there, just ask the dinosaurs.

Back to the topic at hand.

The reason El Niño is important, other than acting like a massive thermostat for the planet, is that it seems to wreak havoc on the Atlantic hurricane season. The simple reason seems to point to higher than normal wind shear and sinking air across the tropical Atlantic due to the presence of the warmer than normal water in the tropical Pacific. In other words, El Niño would be perceived as a positive for those who would rather not deal with hurricanes; except for times when something like Andrew comes along. You can add to that list: Audrey, Camille, Alicia and even all of the landfalls of 2004. Those were all El Niño years. The point is, generally speaking, El Niño has a negative impact on Atlantic hurricane activity but this is not a guarantee. Kind of like how the 2013 hurricane season turned out. You just never know even in the face of what seems like a near certainty.

The reason behind the talk of an impending El Niño is due to several things that we can see going on across the tropical Pacific right now and within the past few weeks.

Pressure differences in the west Pacific have resulted in stronger winds blowing from the west. This causes a change in the way the ocean behaves and helps to generate what is called an oceanic Kelvin wave. I call it a Monkey Wrench in the ocean state. Normally, the trade winds in the Northern Hemisphere blow from east to west and thus the west Pacific is almost always warmer than the east Pacific. When the pressure pattern is altered, for reasons yet unknown, then the wind reverses course and that warm water is pushed eastward. This happens more so at the subsurface believe it or not in what is called downwelling. Warm water is literally pushed downward and then begins a very slow trek eastward where it upwells in to the eastern Pacific. The result: the birth of El Niño. It’s much more complicated but that’s the general idea. No one knows precisely what triggers these events to begin the chain reaction but it appears, at least for now, that forces are being set in to motion that could have huge global impacts as we move through 2014.

As for predictions, computer models are very unreliable for predicting long term weather patterns. They just cannot resolve the complex atmosphere coupled with the ocean several months in advance. In fact, the ECMWF, considered to be the very best global model in the world, called for an El Niño event last summer. It did not happen. So we shall see. While there is mounting evidence to support an El Niño event taking shape this year, it’s not clear at all how strong the El Niño would be. Obviously, the warmer the anomalies (departures from normal or average) then the more dramatic the impacts would likely be. We just don’t know yet.

As for how this potential El Niño will affect the 2014 Atlantic hurricane season – well, let’s just make sure we remember Andrew in 1992 as a case study in “it only takes one”. Sure, the overall numbers may be way down compared to the past 15 years or so. All it takes is for one, and it doesn’t even have to be a hurricane, to spoil the summer fun.

Stay tuned. El Niño is about to show Polar Vortex the door…maybe. I’ll have an update on this in mid-April.

M. Sudduth 9:15 AM ET FEb 25

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