The Eyewall

One-sentence summary

While there remains a lot of noise in the Atlantic for the next 7 to 10 days, the main items of interest from a land-impacting potential may be disturbances that try to form closer to home in the Gulf or near Central America.

Happening now: Noisy but not expecting a whole lot to formally develop this week

Tuesday morning in the Atlantic basin shows a conga line of thunderstorms stretching from northeast of South America all the way to Africa. This is the inter-tropical convergence zone (ITCZ).

On the map above, I’ve annotated the various things we’re watching. Let’s walk through them and what to expect through early this weekend.

Area 1: Easternmost tropical disturbance with 30% odds of developing per NHC

The area with the highest risk of developing over the next week is still over Africa this morning. This particular feature is expected to emerge later today or tomorrow into the Atlantic. It will take a couple days to organize after that, and any development before this weekend would be on the low-end.

I’m actually going to refer you to yesterday’s medium range section for more discussion on this system. Not much has changed in terms of the influences it will feel and why we believe it will launch out to sea. Yes, it has a chance to develop. No, we don’t believe it will develop significantly. And for now at least, we do not anticipate that it will impact land.

Area 2: Tropical wave embedded in the ITCZ halfway across the Atlantic with 10% development odds

The second area highlighted by the NHC is the tropical wave about halfway across the Atlantic. This is embedded in the ITCZ right now, which means it will probably need to break free to really develop. I’m not entirely sure that’s going to occur, and even if it does, this wave will likely be surrounded by dry air and have to fend off some wind shear as it approaches the Caribbean.

So, the 10 percent odds seem reasonable right now, which is to say not impossible that it might develop but unlikely.

Area 2a: A “piece” of that tropical wave that may race toward the Gulf next week

So, to be clear, no development is expected from this area over the next 5 days. But, if you look at some upper level maps, you can pick out a “piece” of this mid and upper level disturbance that comes hauling, I mean hauling west over the next 5 days. It makes it from the middle of the Atlantic to beyond Florida by day 5.

By the end of the near-term, this disturbance is mostly unchanged and continuing to race west. Again, no development is expected.

The medium range (days 6 to 10): Watching the Gulf? Kind of.

Continuing from above, by day 6 (Monday), the disturbance we’re watching moves to just south of Louisiana. And by day 7 (Tuesday) it has come ashore in Texas. There are significant model differences in exactly where this disturbance will go, but it will likely lead to some tropical rains in parts of Texas and/or Louisiana. But given the uncertainty, it bears some watching.

The speed of this disturbance is something else. That is both good and bad. The good news is that a quick moving disturbance will limit its residence time over a record warm Gulf of Mexico.

The Gulf of Mexico this week is the hottest it's been at any point in any year on record by a wide margin. Weekly averaged Gulf sea surface temperatures have never broken 87°F but this week topped 88°F, an astonishing 1.4°C (2.6°F) above the 1991-2020 average. pic.twitter.com/bw2p8RRsBE

— Michael Lowry (@MichaelRLowry) August 13, 2023

Less time over water means less time to organize. Truthfully, the speed of this disturbance itself will be a detriment to development, as systems that move this fast hardly have time to get their acts together. It would be one thing if it were already organized, but it won’t be. Between all that and some moderate wind shear, it seems that this system is unlikely to organize.

The good news is it will bring a meaningful chance of some rain to a bone dry, drought-plagued western Gulf Coast.

The bad news is that because it’s moving so fast, any benefits may be very brief. We will have more on this as it gets closer.

Aside from the Gulf, we’ll continue to watch the system off Africa that we expect to turn out to sea. There may be a second wave that emerges later in the period as well that has some development chances.

Overall, I think you can classify the next 10 days as semi-active. Yes, we have development opportunities, but none are slam dunk cases.

Fantasyland (beyond day 10): Looking closer to home

I’m not entirely sure how the extended range is going to play out. Broadly, the Atlantic basin looks favorable for development. Realistically, however, there’s not a lot sticking out right now. But there seems to be a slight signal in the modeling that some type of hot spot may exist in the Gulf or near the Yucatan, possibly courtesy of a Central American Gyre (CAG) type pattern. Maybe. Gyres are tough to predict, and specific tropical systems emerging off CAGs are even more difficult to predict more than 5 to 6 days out. So I won’t rampantly speculate for you. Other sites can do that.

The map above shows the 51 European model members averaged together to produce a “normalized” 500 mb height anomaly next weekend, or basically what the pattern is doing 20,000 feet above our heads. There’s clearly a signal that some type of upper low or disturbance may be in the vicinity of the Gulf closer to days 12 to 15. Whether that’s an non-tropical upper low, a disjointed area of storms, an organized tropical system, or nothing at all I could not tell you. I’ve done this long enough to know not play speculation games with CAGgy-type setups (and even non-CAG setups too!). For now, I’ll just say let’s watch and wait; there’s enough signal in the models that says “let’s monitor the Gulf.” However, I would not expect much clarity on the specifics of the final days of August for another week or so.

Aside from that, we’ll keep watch on the Atlantic, but I’m not enthused by anything in particular at this time.

We have a lengthier post than usual today to catch you up on the doings of the Atlantic, which may be opening its doors to business this week. We’ll call it a soft opening for now. Just a reminder that you can subscribe and get these posts in your inbox, by signing up for email updates to the right (on desktop) or at the bottom (on mobile).

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One-sentence summary

Hurricane season should pick up some later this week, with one or possibly two systems potentially trying to develop in the eastern Atlantic.

Happening now: Peak season begins this week. Maybe.

The tropics look to remain quiet the next couple days at least, but as waves begin to emerge off Africa this week, we’ll watch the late week period for the potential of some development. If we look at the satellite imagery over Africa this morning, we can see the beginnings of this burst of activity.

From this morass, we expect about two primary disturbances to show themselves. Both the GFS & European models are now in decent agreement on that for day 5.

The eastern Atlantic seems to be the most likely area for development to occur at the tail end of the near-term period, and it would likely be one or two waves that could do it. That being said, there is going to be a lot of “noise” out there with this stuff. You really need these disturbances to break out of this noise to have a good shot at developing; destructive interference can be a thing. The National Hurricane Center currently has odds of 30 and 20 percent for these disturbances to develop in the next 5 to 7 days.

I would say the odds of one system developing is probably above 50 percent right now. The odds of two systems developing is probably 20 percent or less. Either way, we at least know where to watch this week. We’ll talk about the future of these waves below.

Elsewhere, the European model is slightly bullish on a third piece of activity that makes it close to the Lesser Antilles later this week. I would say the odds of that area becoming something are extremely low right now, so we’ll leave it at that. There is another tropical wave that should make it across the Caribbean or end up near the Bahamas later this week as well, but that will not develop this week. More on that one below.

The medium range (days 6 to 10): An in-depth look at what will drive the bus in the Atlantic

So, with so much noise heading into the period and two dominant features in the eastern Atlantic to focus on, let’s check up on three things to see how this might go: Steering currents, dust/dry air, and wind shear.

Steering currents

Where will these systems go? Beginning later this week, high pressure over the central Atlantic will begin to weaken. By Sunday (day 7), we have a map up at 20,000 feet in the atmosphere that looks like this:

High pressure has reformed itself by then, somewhere south of the Azores or near the coast of Africa. What does this mean? Well, at first, given the weaker high pressure, we’ll probably see any system(s) in the eastern Atlantic turn to the northwest fairly quickly, particularly if they form quickly. As that happens and the high re-strengthens, that system or those systems will probably get pushed back to the west some. The good news is that it does not appear (for now at least) that the high pressure area will build west as the potential system(s) comes west. This should keep the exit door open to the northwest and north in the Atlantic. The vast majority of ensemble data suggests this to be the case as well. Ensembles give us 30 to 50 runs of the same model with tweaks, so we get a realistic “spread” of options, and in this case, almost all take it out of the way.

The ensemble here is saying to us “Hey, you’ve got a tropical wave here that has a shot at developing, but it will probably turn northwest before it really gets to impact any land.” We expect that it will turn north right now, but we are not sure exactly when. Obviously we will watch this closely, but for now at least, we think this will turn northwest.

Dry air and dust

There is an awful lot of dry air and dust in the Atlantic — right now.

But notice how it relents some near Africa. Initially, dry air probably won’t be a huge obstacle to overcome. But, if you trust modeling, the dry air is going to be a feature, not a bug.

Above, you see a map of mid-level atmospheric moisture on day 8, next Monday. If we box in the area where disturbances *might* be, and then we delineate dry air from moist air, you can see that there’s definitely dry air back in the vicinity of where this system or these systems may be. Tropical storms do not like dry air. It inhibits their growth and development. Assuming dry air is nearby, then you may have a situation where there is a “cap” on how strong these systems can get.

Shear

Another reason to potentially keep a lid on the ceiling for whatever forms is wind shear.

The wind shear anomalies shown above for the medium range period are less than optimal for tropical storms to develop and strengthen. Wind shear is when winds move in varying directions with height, something that’s not great for hurricanes. The less wind shear, the more hospitable the environment is for tropical systems to grow. For now, this is an okay looking map if you’re rooting against storms.

As always, there are exceptions to the rules, but I think when you look at the sum of the parts right now, between shear, dry air, and the steering pattern, we are not in terrible shape in the Atlantic basin, despite the noise from modeling over the next 10 days.

Elsewhere

Aside from all this, we will have to wait and see if there is any consistency from models on the potential that the lead wave today can manage just enough to survive into the Gulf and then develop, something operational models show to some (modest) extent.

The upper pattern may support the Gulf being open for the Mexico or Texas coast next week, with high pressure centered over Missouri, farther north than it has been most of summer. The question as always is can we do anything with it? We’ll discuss that more through the week.

Fantasyland (beyond day 10): Active pattern may continue

As of right now, there are no specific concerns in the Atlantic heading out into the longer range. I do believe the pattern will remain fairly active, but the question will be whether or not the hurdles of shear and dry air will be low enough for storms to overcome. We’ll have to wait and see.

One-sentence summary

The near-term remains quiet, while the Atlantic looks to pick up the pace next week but no serious land threats are seen at this point.

Happening now: Bahamas wave remains the only thing on the board this weekend & remains unlikely to develop

We head into the second weekend of August with a clean plate! We’ll take it. It’s quiet for the next few days. We continue to mic check the wave in the Bahamas that’s heading toward Florida now. It remains very disheveled this morning.

Over the next 5 to 7 days, what’s left of this wave is actually likely to traverse the southern Gulf but seems likely to fall apart before bringing some needed moisture to drought plagued Texas and northern Mexico.

With development not expected from that, we could look out into the deep Atlantic, but there are no signs of development there over the next 4 or 5 days either.

The medium range (days 6 to 10): Atlantic action Jackson!

Well, let’s see how this goes. Modeling continues to insist that one or several waves off Africa next week will develop as they come west. As best I can tell, the Euro is picking up on potentially three waves, none of which are expected to rapidly organize.

Let’s keep in mind that the European ensemble (the 50+ runs of the Euro model with various tweaks) has been rather aggressive in developing tropical waves in the main development region of the Atlantic this year. So this may be a bit overconfident. But I just want to give you an idea of what we’re watching next week.

Alright, so let’s say the Euro is correct here and we have, call it 2 or 3 tropical waves that could develop. What does this model think of the pattern and conditions of the Atlantic next week? We’ll start with a look at humidity. Dry air acts to inhibit tropical development. Tropical systems like moisture, not dry air. Looking at the mid-levels of the atmosphere, we can actually see the Atlantic has a fair bit of dry air present. That’s a caution flag to me.

If we look up around 20,000 feet, which we refer to as the 500 millibar (mb) level, we can get a good sense of what will be “guiding” any tropical systems next week. It would seem that high pressure over the open Atlantic will establish between Bermuda and the Azores. This may mean two things. First, it’s entirely possible that at some point that’s enough to force any quicker developing tropical systems to turn north quicker.

Over time next week, that high may actually nudge farther east, as high pressure reasserts itself over the United States. What this could do is open the exit door for escape of any tropical waves, ideally before they get to the Caribbean islands.

So, yes, we expect that tropical waves have a chance at developing next week, but we also think that the upper level steering pattern and mid-level dry air will help keep intensity in check and hopefully leave the door open for an early exit out to sea. Keep in mind that we’re talking about a 7 to 10 day forecast here, and a lot can change! But sitting here today, those are our thoughts.

Fantasyland (beyond day 10): Punt

Much like yesterday, I am intentionally punting on the extended range part of the forecast today because there’s too much volatility in the medium-range to even try to make sense of anything beyond day 10. So let’s how next week shakes out first, and then go from there.

NOAA Outlook

Just to cap this post, the National Oceanic and Atmospheric Administration (NOAA) issued their seasonal forecast update yesterday. It did increase the odds of an active season, but I don’t believe it particularly sheds any new light on things. We knew this season would be a battle between an El Niño event emerging that has historically led to quieter activity and Atlantic and Gulf and Caribbean sea-surface temperatures that are extremely warm, if not record warm. So far, the home team has won, and we hope that continues the rest of the season. But there are some notable things in the background that give seasonal forecasters reasons to be wary, and I think that explains their boosted outlooks this year. Remember to prepare each season as if it will be the one that delivers you a storm, regardless of seasonal outlooks.

One-sentence summary

A wave near the Bahamas is unlikely to develop over the next few days, but support is growing for some development of a wave emerging off Africa later next week.

Happening now: Bahamas wave unlikely to develop

Things remain quiet in the tropics for the near-term. We do not expect any development from any areas. The most prominent feature continues to be a tropical wave near the Bahamas.

Modeling continues to view this area unfavorably, and no development is expected from it. But since we watch things closely, let’s just talk briefly about why it probably won’t develop.

Wind shear is not the issue, as this wave is embedded in an area of lower shear. But there is a fair bit of dry air around this wave. Yesterday I noted how a surge of mid-level dry air into the Southeast this weekend or early next week would likely eviscerate this wave. That’s still on track.

But given the low shear environment, we’re sort of lucky to already have some dry air around the system. Otherwise, I think it would be a potential candidate for development. We’ll continue to watch it into the weekend, just in case. But for now, we feel confident that this will not form.

Elsewhere, things are quiet.

The medium range (days 6 to 10): Model support growing for wave off Africa to develop next week. Maybe.

The next item to watch will be emerging off Africa in the coming days. We are beginning to see some actual model agreement now between the GFS and Euro that suggest a wave or waves will develop later next week. The trouble right now is that there are a lot of disturbances in that part of the world, and it’s tough to really say with any confidence which one it will be that goes, if any do at all! The European ensemble model shows this really well.

Recall, ensemble models are basically when you take the same model and run it 30 (GFS) to 50 (Euro) times with tweaks each time. If you look at the individual ensemble members, you get a more realistic spread of potential outcomes. Indeed, when you look at the European ensemble right now, you can make absolutely zero sense of things. Which wave? When does it develop? Is it multiple waves? What is life?

As a forecaster, all I can do is look at that and tell you, “Hey, a wave emerging off Africa in 3 to 5 days has a good chance of developing later next week.” That’s where our focus will be in the medium range. Confidence is not terribly high given how the Atlantic has underachieved this season. And quite frankly, this may be telling us that the Atlantic ends up too chaotic for development. That’s very much a possibility as well. We’ll see how this evolves.

Fantasyland (beyond day 10): Who knows?

I’ll be honest with you. Given the uncertainty surrounding next week’s wave off Africa, it doesn’t make sense to tinker much with the “beyond day 10” period. I personally expect this medium-range wave(s) to be the main storyline heading into the longer range, should it develop. Behind that, we’ll continue to watch the African wave train do its thing as we head toward September. You can count on us for sober, level-headed, no hype coverage of all of it in the coming weeks. If you haven’t already, tell your friends or family on the coast from Newfoundland to New Orleans to Nicaragua that we’re here to help folks make sense of hurricane season!