Two tropical waves to monitor in the Atlantic

Satellite photo with invest areas 96L and 97L indicated

Satellite photo with invest areas 96L and 97L indicated (click to view full size)

We now have two areas to keep tabs on in the deep tropics. Both systems are far from land and really don’t have much of a future ahead of them due to limiting factors in the atmosphere.

The first, invest area 96L, is the eastern most tropical wave with a weak surface low associated with it. Overall, the system has become better organized since yesterday. The development of new convection or thunderstorm activity seems to be persisting though it is not very strong due to weak instability and overall upward motion in the region. This will likely keep 96L from strengthening too much in the coming days as it moves steadily westward over the open Atlantic.

Next we have area 97L which is moving a lot faster towards the west due to strong high pressure to its north. Convection is limited right now and the quick pace of movement will likely help to hinder additional development as the wave of low pressure continues westward.

It does appear that portions of the Leeward Islands will experience a period of squally weather as the tropical wave passes through this weekend. Interests in the region, especially boaters out in the open water, need to be aware of this system.

The fast movement of 97L means that what ever energy survives the coming days could end up in the western Caribbean early next week and while computer models are not indicating development there, we’ll have to watch to be sure. I still think it is just a little early to expect prolific development out of these tropical waves just yet. Give it another couple of weeks and things will probably be different and this makes sense considering the normal uptick in activity as we head in to August.

Meanwhile, the eastern Pacific refuses to shut down completely. We now have invest area 91E which is well on its way to developing well off the coast of Mexico. Fortunately, the steering pattern remains locked in for now and what ever manages to get going will move farther out in to the Pacific and not be an issue for Mexico.

I will have more here over the weekend.

M. Sudduth 11 AM ET July 29


96L probably won’t develop and here’s why

Tropical weather watchers have had something to monitor for about 24 hours now with the designation of invest area 96L out in the far eastern Atlantic. While it is a sign of the changing pattern and move towards the climatological uptick in hurricane activity, I don’t think this particular system is, by itself, anything to be concerned with – at least not yet.

As I pointed out yesterday, water temperatures in the region of the MDR or Main Development Region are warm enough to support tropical storm formation. We have an area of energy, the tropical wave, entering the Atlantic from Africa and it would seem that all systems are go for this to develop. Let me explain, at least the way I see it, why this probably won’t happen.

Vertical instability or the ability of the atmosphere to produce convection is still somewhat below average in the deep tropics right now. This may be why 96L is not developing for the time being

Vertical instability or the ability of the atmosphere to produce convection is still somewhat below average in the deep tropics right now. This may be why 96L is not developing for the time being

Wind shear is low, water temps are warm, so why are we not seeing a marked increase in convection or thunderstorm activity with 96L? I believe it has to do with the overall instability of the atmosphere in the region. The air is still not quite moist enough in the mid levels and perhaps there is still a layer of warmer, more stable air present over the deep tropics. To put it in simple terms: the lack of instability seems to have a cap on thunderstorm development. This seems to have been an issue for development potential for the past several years, dating back most notably to 2013. However, last year, we saw hurricane Fred develop way out in the east Atlantic, almost in the same vicinity of where 96L is now. So what gives? Fred formed at the end of August, we’re only at the end of July. I think the additional time for the atmosphere to moisten up really does matter. Africa tends to contribute an incredible amount of dry, warm, particulate-laden (dust) air in to the MDR and this just takes time to mix out.

So what does this mean for 96L and the rest of the hurricane season? I believe that these recent robust tropical waves will progress westward with little fanfare, only to spring to life farther to the west where conditions are generally more favorable. Then, as the season evolves towards late August and in to September, the chances of one or two long-track hurricanes will go up. After all, the water temperature profile in the deep tropics is warmer than average just about everywhere. There is no abnormal cooling this year and no El Nino effects present. In short, it is only a matter of time and if these systems do in fact lay quiet as they work their way west before developing, then it could mean a very busy landfall season for the countries of the western Atlantic Basin – which of course includes the United States.

For now, 96L will be an interesting topic of conversation. In the longer term, I would be surprised if it developed further – but it won’t just disappear and we may have to deal with it later on when it reaches the western Atlantic. I guess time will tell – it always does.

I’ll have more this afternoon in my video discussion which is posted to our app, Hurricane Impact, and to our YouTube channel.

M. Sudduth 9:45 AM ET July 28


Tropical wave in far eastern Atlantic worth watching

Tropical wave, designated at invest 96L,. moving off the coast of Africa

Tropical wave, designated as invest 96L, moving off the coast of Africa

It is late July and the tropics are beginning to shows signs of life. After several weeks of a very busy east Pacific, the tables are slowly turning and it won’t too be long before the Atlantic begins producing storms and hurricanes.

Right now the focus is on a strong tropical wave emerging from the west coast of Africa. The National Hurricane Center has designated it as invest area 96L – the first step in the process of watching for potential development. In this case, the potential for additional development is rather low, only 20% out to five days. However, it is the fact that we have something of interest entering the so-called MDR or Main Development Region that makes this situation interesting.

Climatology suggests that while development is possible this early in the season in the tropical Atlantic, it doesn’t happen too often. Dry mid-level air, typically associated with Saharan Air Layer outbreaks off of Africa, usually squash development potential until later in August. That may be what we see in this situation though it doesn’t mean the tropical wave will vanish.

Water temps, outlined in green here, are warm enough in the far eastern Atlantic to support development

Water temps, outlined in green here, are warm enough in the far eastern Atlantic to support development. The contour lines show temperatures of the sea surface in degrees Celsius and typically anything above 26C is warm enough to support tropical storms and hurricanes

Water temps are warm enough in the region off the African coast and overall, upper level winds are generally favorable.

Some long range models suggest that the wave of energy will wait until it reaches the western Atlantic before developing. We have seen this time and again in recent years as the MDR has seemed to be rather hostile for seedling storms to take root.

Right now, it is a topic of conversation for tropical weather watchers and TV meteorologists. Whether or not 96L becomes more of a story later on remains to be seen. It is certainly a sign that we are getting closer to the prime time of the Atlantic hurricane season and with so much warm water waiting in the western regions of the basin, it’s only a matter of time in my opinion – which makes sense considering the time of year we are in and where we are headed climatologically speaking.

Meanwhile, the east Pacific remains fairly busy with tropical storm Frank dying out well to the west of the Baja peninsula where cooler water and a more stable air mass awaits.

The NHC has outlined an additional area of interest farther to the southeast of Frank that has some potential for development over the next five days. No worries for Mexico, however, as anything that does manage to get going will move generally west to west-northwest out in to the open Pacific.

I will have more on 96L in my video discussion later today and a full blog post again tomorrow morning.

M. Sudduth 11AM ET July 27


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


Hurricane Bertha: 1996

Hurricane Bertha on July 12, 1996

Hurricane Bertha on July 12, 1996

On this day, 20 years ago, hurricane Bertha made landfall in southeast North Carolina and with that, sealed my fate with a career “in the business”.

The early July hurricane made headlines as being quite strong for so early in the season – reaching category three intensity not far from Puerto Rico on July 9.

After a period of steady weakening up until July 11, Bertha found new life in the warm Gulf Stream just off the South Carolina coast and once upper level winds relaxed, the hurricane quickly strengthened to 105 mph. During the afternoon of July 12, Bertha made landfall north of Wrightsville Beach. It was the first of five hurricanes that would make landfall in the Cape Fear region between 1996 and 1999.

Photo of me, 20 years ago today, holding a Davis anemometer up to record wind speed at the Wrightsville Beach drawbridge as hurricane Bertha was about to make landfall

Photo of me, 20 years ago today, holding a Davis anemometer up to record wind speed at the Wrightsville Beach drawbridge as hurricane Bertha was about to make landfall

For me, Bertha was the opportunity to do something that I had always wanted to do. I took my Davis weather station to the foot of the draw bridge at Wrightsville Beach and walked out as far as I could to the open area near the top of the span. I held the anemometer as high above my head as possible to record wind speed. It was far from perfect and certainly not very scientific, but for someone who grew up glued to The Weather Channel, watching Dennis Smith, Jim Cantore, Jill Brown and others while they worked hurricanes of the past, it was my moment. The rain stung my cheeks. Lightning cracked the sky (yes it really did lightning as the outer bands moved on shore) and the wind did all it could to buffet me as I stood by myself on that bridge.

Within a minute or so, several reporters braved the elements and rushed out to interview me. Some asked if I were a storm chaser. Others wanted to know if I worked for NOAA. I answered simply with, “I just wanted to know how fast the wind was blowing”. This was enough to pique their interest. My picture was taken and it accompanied an article in the Winston-Salem Journal the next day (oh how I wish we had Twitter, etc back then).

The anemometer recorded a gust to 70 mph. To the reporters on the bridge that afternoon, this was gold. They had something they could report on other than the usual stuff about people boarding up, evacuations being ordered and so on. As non-scientific as it was, I had data. I knew that this moment would define the rest of my career and that the lack of accurate data at landfall was a problem. From that moment on, I have worked to develop ways to measure hurricanes at landfall, not only through scientific equipment but also through the use of unmanned video of storm surge and other effects. And to think, it all began on that bridge as hurricane Bertha inked its place in North Carolina’s hurricane history.

M. Sudduth 12:30 PM ET July 12