One ingredient is in place: very warm ocean temps

As we all know by now, it takes a very specific set of ingredients coming together at the right time to produce tropical cyclones – and in our case, hurricanes. Sometimes all of the pieces are seemingly there, yet nothing happens. One key element of the whole process is warm water, there is no doubt about that. Warm water, usually around 80F or higher, is what fuels hurricanes and the warmer it is, the stronger they can become.

Sea surface temperature anomalies (departure from normal) showing a very warm western Atlantic, Gulf and Caribbean Sea. Contrast this to the cooling tropical Pacific and it could make for a busy August-October for hurricanes in the Atlantic.

Sea surface temperature anomalies (departure from normal) showing a very warm western Atlantic, Gulf and Caribbean Sea. Contrast this to the cooling tropical Pacific and it could make for a busy August-October for hurricanes in the Atlantic.

This year, water temps in the western portion of the Atlantic Basin are warmer than normal in most locations. Check out the very latest anomaly map which shows the departures from normal across the region. Clearly, the Gulf of Mexico sticks out as does the western Atlantic just off the Southeast coast. Also of note, the Caribbean Sea has several areas of positive anomalies – meaning that water temperatures are above normal.

Obviously, none of this will matter unless there is a hurricane to tap in to the vast energy stored in this warmer than normal water. Right now, I see nothing in the global models to indicate that anything will be developing in the near future – all of the action is in the east Pacific right now. In fact, I have a theory that with all of the constant hurricane activity between Hawaii and Mexico, perhaps the sea surface temps will be cooled enough to create a stark contrast between the Pacific and the Gulf of Mexico/Western Caribbean. This could create more favorable conditions later in the season for that region – we will just have to wait and see about that.

For now, the warm water is in place, there’s no doubt about that. Whether or not it becomes a factor during the heart of the season, still a month away from beginning, remains to be seen. It will be something to keep an eye on for sure.

I will have more later in the week.

M. Sudduth 1:40 PM ET July 18

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Consensus growing for active hurricane season

We are now less than three weeks away from the start of the 2016 Atlantic hurricane season and already it looks to be a busy one. Before we jump to the “sky is falling” conclusion, let’s look at things objectively and put it in to some perspective that most can understand.

Subsurface anomaly chart showing the growing area of cooler than normal water mounting in the tropical Pacific

Subsurface anomaly chart showing the growing area of cooler than normal water mounting in the tropical Pacific

What we know is that the great El Nino of 2015/16 is almost certainly dying out. We can see this by looking at various data from a variety of sources. One of those is the subsurface anomaly chart that I have included here. Clearly the warm surface water is being eroded away with a vast expanse of cooler than normal water lurking across most of the tropical Pacific. This will very likely herald the arrival of La Nina conditions or an abnormal cooling of the Pacific along the equatorial region. In short, this is typically seen as a favorable sign for the development of Atlantic hurricanes. The sooner we see La Nina set in, and the stronger it is, the more influence it will have on enhancing the chances for Atlantic hurricane development once the season gets going.

In addition, we also know, again by looking at actual data, not computer model projections, that the Atlantic Basin is warming in the area between Africa and the Lesser Antilles. This is also called the MDR or Main Development Region. The irony here is that there were some indications in previous weeks that this region would actually cool abnormally; so far, it has done the opposite.

Check out the very latest NOAA/NESDIS SST anomaly map for the region. Water temps are running above normal across the entire MDR and in to the Caribbean Sea. This is a stark difference from what we saw last season although the MDR did warm some as the season progressed. Right now, the region is warmer than we have seen it since the 2013 season and this, coupled with the loss of the El Nino, should give another check mark in the column of enhanced hurricane Activity for the Atlantic.

Latest NOAA/NESDIS SST anomaly map showing a very warm tropical Atlantic

Latest NOAA/NESDIS SST anomaly map showing a very warm tropical Atlantic

Warm water alone does not make hurricanes. The atmosphere needs to cooperate as well with aspects such as moisture level and wind shear being take in to account. Right now, those parameters don’t matter too much since it’s just May. However, conditions do seem to be a little less dry in the mid levels of the atmosphere in parts of the tropical Atlantic which is yet another indication that things may be busier than we’ve seen for quite some time. Shear will drop as the summer approaches and the westerlies retreat to the north. Once we get to August, the beginning of prime time for the season, it looks like all systems go for a busy time ahead.

With all of this mounting evidence for a busy season, it comes as no surprise that several respected agencies are forecasting either an average season or slightly above average. So many different entities are making forecasts now that it’s hard to keep up. The trend however is what is interesting to me. All of them see a busier Atlantic than the past few seasons and that will seem very busy considering how relatively quiet things have been since 2012. We will get a new forecast from Dr. Phil Klotzbach and his team at CSU in early June. NOAA will release their seasonal outlook soon as well. I think it is safe to say that, at least for now, the scale has tipped in favor of the Atlantic.

None of this matters as far as who would be impacted. I need to make that very clear. Knowing that the general large scale environment favors more hurricanes is helpful, I think anyone would agree with that. You’d rather know than not, right? Just don’t get caught up in the headlines and lose sight of the fact that even a 40 mph tropical storm can ruin your entire life – or even end it. It’s all about the impact (hence why our app is called Hurricane Impact) and no forecast can tell you with any degree of certainty what impact you will face this season.

The bottom line here is that you’re going to hear a lot about the “busy hurricane season” coming up. What you won’t hear as much about is how you can process that information and make use of it. My advice is to use that info to beef up your knowledge of hurricanes and what to do if one comes your way. A busy season does not necessarily equate to one with many (or any) landfalls. It does up the chances but no one really knows by how much. That part of the equation comes down to timing and placement of the would-be hurricane within the Basin.

It’s almost time. We are ready and hope to help you to be as well.

I’ll have more here on the 15th when the east Pacific hurricane season begins.

 

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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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Latest forecast suggests no El Nino in sight

Latest CPC/IRI ENSO forecast chart

Latest CPC/IRI ENSO forecast chart

It’s approaching mid-June and the latest info from the Climate Prediction Center and International Research Institute (CPC/IRI) suggests that El Nino is not going to happen this hurricane season.

First, what is El Nino and why is it an issue? Well, basically, it is the abnormal warming of the tropical Pacific along and near the Equator. This warming tends to throw off the typical weather pattens and usually equates to a below-average Atlantic hurricane season. This is due to stronger upper level winds, or shear, that streaks across the tropical Atlantic and Caribbean, cutting off the tops of developing hurricanes. In the absence of El Nino, we often experience a busy Atlantic hurricane season, especially if the tropical Atlantic sea surface temps are themselves running above average – as is the case this season.

For reasons not well understood, El Nino comes and goes every few years. In between we have neutral periods where the water temps are more or less average. Then we have La Nina or an abnormal cooling of the tropical Pacific. That phenomenon also has its own set of interesting side-effects which are better explained another time. For this season, we are looking at a neutral pattern setting up and remaining in place.

The latest data and forecast from the CPC/IRI suggests less than a 10% chance of seeing El Nino develop during the August/September/October peak time of the Atlantic hurricane season. This should act to allow for prolofic development once we reach mid-August and beyond, especially considering the warmer than average SSTs in the Atlantic.

This chart gets updated a couple of times per month and I’ll post another write up on the state of the ENSO or El Nino Southern Oscillation towards the end of the month. In the meantime, the tropics are nice and quiet with no areas of concern noted in either the east Pacific or the the Atlantic.

M. Sudduth

 

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How’s that La Niña going?

Subsurface Temps of the Tropical Pacific

Subsurface Temps of the Tropical Pacific

So far this winter, the La Niña that has been in place since last fall continues to hold strong. As the graphic from the Bureau of Meteorology in Australia indicates, subsurface temperatures across the tropical Pacific remain much colder than average over a large area. There is a growing region of subsurface warmth beginning to pool in the western Pacific but it lacks a real mechanism to drive it eastward- a so-called westerly wind burst. We typically don’t see those unless there is a significant pressure change across the Pacific and that shows up in the SOI or Southern Oscillation Index. When it is substantially negative, and persistently so, the trade winds often slow or even reverse, allowing the warm water gathering in the western Pacific to migrate eastward.

The latest update from the BOM also points out that long range climate models suggest a gradual warming of the tropical Pacific as the La Niña fades. This means it is likely that we’ll see a return to more average, or neutral ENSO conditions (ENSO stands for El Niño Southern Oscillation) by the time summer arrives in the Northern Hemisphere. There is also the possibility that the warming will continue and a weak El Niño could set in by next fall. I do not see any evidence yet to suggest that a strong El Niño is coming. However, this time of year, it is difficult to predict what will happen several months down the road but the large subsurface cold pool coupled with a fairly strong SOI signal over the past 30 to 90 days tells me that La Niña is going to be the rule for a few more months at least.

Why does any of this matter? Aside from the effects outside of the hurricane season, which are far too detailed to get in to in this post, we typically see a more active hurricane season when El Niño is not present. This is due to the stronger and more numerous instances of wind shear, the change of wind speed and/or direction with height, over the deep tropics. El Niño events promote this negative impact to tropical cyclones where as La Niña events usually do not.

For now, the La Niña pattern will continue but we’ll watch for signs that it is breaking down and then we’ll see how much warming takes place in the tropical Pacific. The end result could have an impact, one way or another, on the upcoming Atlantic hurricane season. I’ll post more about the ENSO state next month.

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