2024 Hurricane Season Discussion

[Cpv17]

EPS from last night had an 80-90% probability of this wave becoming at least a TD in the BOC, and yet everyone on storm2k is writing it off completely, ill never understand this kind of thinking, i just dont get it lol

Storm2K is very east coast based, especially FL when it comes to the tropics.

[tireman4]

Matt Lanza

[tireman4]

Caribbean wave struggling but worthy of monitoring, while the surprisingly muted Atlantic plods forward
September 3, 2024 at 1:39 pm by Matt Lanza
Headlines
A tropical wave in the Caribbean maintains about a 30 percent chance to develop in the coming days.
Model guidance doesn’t quite eliminate that wave as a potential area to monitor for the Bay of Campeche and/or Gulf, but very few models are bullish on intensity right now.
The rest of the Atlantic is rather quiet for September.
A potentially historic rain event in the Sahel and Sahara Desert may be symptomatic of bigger issues at play that could partially explain some of this season’s failure to launch.
Caribbean wave continues to lurk
The number of forecast consensus iterations on this Caribbean tropical wave over the last week or so have been rather annoying. Initially, we were discussing a system possibly heading out to sea. Then we started to discuss development farther west in the Caribbean followed by either a turn north or a continued track west. Then, even yesterday it looked like this was doomed to fail completely. And now today we have a new possible forecast wrinkle. In some ways, that’s “chasing” models, a practice that is not enjoyable, nor especially recommended. In other ways, I’m not sure what else you’re supposed to do with a struggling tropical wave that refuses to organize. It’s “guidance” for a reason, and in this case, the guidance has been shifting about.

Anyway, end rant. here’s the Caribbean wave on satellite this afternoon.


A tropical wave in the central Caribbean is producing widespread thunderstorms across Hispaniola and points south and east of Jamaica.
I mean, that’s a respectable amount of thunderstorm activity. But there’s no organization to things here. At least not yet. That could change in the coming days but probably not before Friday. Admittedly, this system is a bit confounding in that it’s generally in a healthy environment to organize but thus far it is not doing so. It could be sinking air in the background suppressing things, it could the 20 to 25 mph forward speed of the system, or it could be proximity to Hispaniola that is currently holding it back. As this reaches the western Caribbean, it may have a slightly better opportunity to organize, albeit slowly. Expect this to be positioned off the east coast of the Yucatan or near Belize by Thursday night.

From there, we will embark on a choose your own adventure scenario with this. A trough over the Eastern U.S. will attempt to pull this system north — if the system can gain enough strength to do so. That seems unlikely at this time. Steering currents will sort of collapse as that trough pulls away, leaving the system in the Bay of Campeche or nearby just sort of wandering aimlessly.


An animation of the mid-levels of the atmosphere between day 5 (Sunday) and day 10 (Thursday) shows the ensemble mean with a signal for the tropical system in the Bay of Campeche, but a complete break-down in confidence on placement late.
You can see that above with last night’s European ensemble modeling. The mean of the 51 ensemble members shows a good signal for some sort of disturbance in the Bay of Campeche by Sunday but then a gradual dissolution of the signal by next Thursday. This suggests that the system will meander in or around the Bay of Campeche, maybe even onshore in Mexico next week. From there, as the steering currents collapse, we could see some northward drift to the system, particularly if it begins to organize. So no one should be entirely ruling this out. But at this point, there are mostly a bunch of hypotheticals and no clear signal on potential track or impacts, except to say that most guidance is generally lower-end with this one, the exception being the ICON model and some AI modeling.

In fact, as of the latest NHC tropical weather outlook, development odds with this have dropped to 30 percent.


A trio of tawdry tropical waves across the Atlantic.
The Atlantic remains calm, mostly
There are two other areas noted on the NHC outlook above. Neither one should impact land over the coming days. The trailing wave closest to Africa may have the better chance to develop, though admittedly the leading wave looks a little healthier at the moment.

Bless the rains (up?) in Africa
But there are weird things happening right now, and we’ll certainly get into them in the days ahead. For one, tropical waves may again emerge too far north off Africa to really produce much in the way of development. In fact, if you look at the forecast rainfall as a percent of normal in Africa over the next 2 weeks, it very clearly shows that portions of the Sahel and even the Sahara Desert are expected to get more than their fair share of rainfall.


Rainfall over the next 2 weeks looks to be on the order of 750 percent of normal in northwest Africa, a truly extraordinary rain event in one of Earth’s driest locations.
This is truly odd. And possibly historic. Now, the amount of rain that can produce 500 to 750 percent of normal rainfall in those areas is probably a lot less than you’d expect. When your average precipitation totals are miniscule, well it doesn’t take much. But still, it’s impressive. There was a decent write-up about this from a site over in Europe that I think touches on some of what’s happening here, key among it: The inter-tropical convergence zone (ITCZ) is displaced just enough farther north than normal to have a strong impact on what we see in the Atlantic. Everything is connected in some way, and it’s plausible that such an outlier event is in some way related to the extreme, historic warmth of the Atlantic Ocean right now. I don’t want to overshoot my skis here, as this is not a topic I’m overly familiar with. But it will merit research and further analysis.

Some of the seeds of that research have been done already, with a recent paper led by author Dr. Kelly Nuñez Ocasio from Texas A&M. Their work suggests that more moisture in the atmosphere as both the oceans and atmosphere warm with climate change can lead to a shift in tropical wave coupling with thunderstorms. In other words, you would get something like we see now, with more waves and storms to the north, and less robust waves emerging off Africa in the places we expect to see them in September. It’s a fascinating study, and given that the paper was published in June, it could not be more timely.

Is this what we’re seeing? Maybe. There’s a theory that supports it, but you obviously can’t prove anything based on one event in one season. But given that we’re probably about to hear a whole lot of people screaming “bust” at the top of their lungs with respect to this hurricane season, it makes for a provocative possible explanation, among other things we’ve touched on.

[Cpv17]

Matt Lanza

As far as I’m concerned, this season has been the biggest bust so far that I can remember. I really don’t remember 2013 tbh. I was into weather back then, but I guess I’m into it more now. It’s going to be very interesting to see what’s causing this lack of activity. I would’ve never thought that this would happen.

[Stratton20]

EPS is almost certain this will become at least a TD

[Stratton20]

All of the mesocale guidance now wants to develop our disturbance in the NW gulf into a TS and slowly stall or meander it around the texas coast in 2 days

[biggerbyte]

There are good points to be had. Any possibility at all, especially for us in Texas bears watching. I agree that no matter how it looks, several possibilities are being thrown around.

Watch what happens with the disturbance in the gulf coupled with this next system crossing over into the BOC.
If you want to watch the models, the ICON goes to the top this year.

[Cpv17]

All of the mesocale guidance now wants to develop our disturbance in the NW gulf into a TS and slowly stall or meander it around the texas coast in 2 days

It’s more of the same though. I saw the HRRR has very little rain for my area. Most of it is along the coast and into Louisiana. Same crap that’s been happening for a week now.

[Stratton20]

If anything its the front thats to blame, i can guarantee you if the front wasnt making progress down here, we’d probably have a lot more rain in land

[Cpv17]

If anything its the front thats to blame, i can guarantee you if the front wasnt making progress down here, we’d probably have a lot more rain in land

Yep, the front is going to block anything from coming here. I’m surprised about all the rain out in central Texas. No clue where all that’s coming from.

[Stratton20]

Cpv17 but yet the CPC updated this today on their site, clearly they are seeing something that we arent lol

[Cpv17]

Cpv17 but yet the CPC updated this today on their site, clearly they are seeing something that we arent lol

Yeah, but I think the SE will see most of that action. The precipitation outlooks on there favor that area more than us.

[Ptarmigan]

Caribbean wave struggling but worthy of monitoring, while the surprisingly muted Atlantic plods forward
September 3, 2024 at 1:39 pm by Matt Lanza
Headlines
A tropical wave in the Caribbean maintains about a 30 percent chance to develop in the coming days.
Model guidance doesn’t quite eliminate that wave as a potential area to monitor for the Bay of Campeche and/or Gulf, but very few models are bullish on intensity right now.
The rest of the Atlantic is rather quiet for September.
A potentially historic rain event in the Sahel and Sahara Desert may be symptomatic of bigger issues at play that could partially explain some of this season’s failure to launch.
Caribbean wave continues to lurk
The number of forecast consensus iterations on this Caribbean tropical wave over the last week or so have been rather annoying. Initially, we were discussing a system possibly heading out to sea. Then we started to discuss development farther west in the Caribbean followed by either a turn north or a continued track west. Then, even yesterday it looked like this was doomed to fail completely. And now today we have a new possible forecast wrinkle. In some ways, that’s “chasing” models, a practice that is not enjoyable, nor especially recommended. In other ways, I’m not sure what else you’re supposed to do with a struggling tropical wave that refuses to organize. It’s “guidance” for a reason, and in this case, the guidance has been shifting about.

Anyway, end rant. here’s the Caribbean wave on satellite this afternoon.


A tropical wave in the central Caribbean is producing widespread thunderstorms across Hispaniola and points south and east of Jamaica.
I mean, that’s a respectable amount of thunderstorm activity. But there’s no organization to things here. At least not yet. That could change in the coming days but probably not before Friday. Admittedly, this system is a bit confounding in that it’s generally in a healthy environment to organize but thus far it is not doing so. It could be sinking air in the background suppressing things, it could the 20 to 25 mph forward speed of the system, or it could be proximity to Hispaniola that is currently holding it back. As this reaches the western Caribbean, it may have a slightly better opportunity to organize, albeit slowly. Expect this to be positioned off the east coast of the Yucatan or near Belize by Thursday night.

From there, we will embark on a choose your own adventure scenario with this. A trough over the Eastern U.S. will attempt to pull this system north — if the system can gain enough strength to do so. That seems unlikely at this time. Steering currents will sort of collapse as that trough pulls away, leaving the system in the Bay of Campeche or nearby just sort of wandering aimlessly.


An animation of the mid-levels of the atmosphere between day 5 (Sunday) and day 10 (Thursday) shows the ensemble mean with a signal for the tropical system in the Bay of Campeche, but a complete break-down in confidence on placement late.
You can see that above with last night’s European ensemble modeling. The mean of the 51 ensemble members shows a good signal for some sort of disturbance in the Bay of Campeche by Sunday but then a gradual dissolution of the signal by next Thursday. This suggests that the system will meander in or around the Bay of Campeche, maybe even onshore in Mexico next week. From there, as the steering currents collapse, we could see some northward drift to the system, particularly if it begins to organize. So no one should be entirely ruling this out. But at this point, there are mostly a bunch of hypotheticals and no clear signal on potential track or impacts, except to say that most guidance is generally lower-end with this one, the exception being the ICON model and some AI modeling.

In fact, as of the latest NHC tropical weather outlook, development odds with this have dropped to 30 percent.


A trio of tawdry tropical waves across the Atlantic.
The Atlantic remains calm, mostly
There are two other areas noted on the NHC outlook above. Neither one should impact land over the coming days. The trailing wave closest to Africa may have the better chance to develop, though admittedly the leading wave looks a little healthier at the moment.

Bless the rains (up?) in Africa
But there are weird things happening right now, and we’ll certainly get into them in the days ahead. For one, tropical waves may again emerge too far north off Africa to really produce much in the way of development. In fact, if you look at the forecast rainfall as a percent of normal in Africa over the next 2 weeks, it very clearly shows that portions of the Sahel and even the Sahara Desert are expected to get more than their fair share of rainfall.


Rainfall over the next 2 weeks looks to be on the order of 750 percent of normal in northwest Africa, a truly extraordinary rain event in one of Earth’s driest locations.
This is truly odd. And possibly historic. Now, the amount of rain that can produce 500 to 750 percent of normal rainfall in those areas is probably a lot less than you’d expect. When your average precipitation totals are miniscule, well it doesn’t take much. But still, it’s impressive. There was a decent write-up about this from a site over in Europe that I think touches on some of what’s happening here, key among it: The inter-tropical convergence zone (ITCZ) is displaced just enough farther north than normal to have a strong impact on what we see in the Atlantic. Everything is connected in some way, and it’s plausible that such an outlier event is in some way related to the extreme, historic warmth of the Atlantic Ocean right now. I don’t want to overshoot my skis here, as this is not a topic I’m overly familiar with. But it will merit research and further analysis.

Some of the seeds of that research have been done already, with a recent paper led by author Dr. Kelly Nuñez Ocasio from Texas A&M. Their work suggests that more moisture in the atmosphere as both the oceans and atmosphere warm with climate change can lead to a shift in tropical wave coupling with thunderstorms. In other words, you would get something like we see now, with more waves and storms to the north, and less robust waves emerging off Africa in the places we expect to see them in September. It’s a fascinating study, and given that the paper was published in June, it could not be more timely.

Is this what we’re seeing? Maybe. There’s a theory that supports it, but you obviously can’t prove anything based on one event in one season. But given that we’re probably about to hear a whole lot of people screaming “bust” at the top of their lungs with respect to this hurricane season, it makes for a provocative possible explanation, among other things we’ve touched on.

I suspect that the rains going to Sahara and Sahel plays a role in why it has been quiet in the Atlantic.

How the West Pacific is playing a role.
https://www.youtube.com/watch?v=cKC8V9HNeYA

[Ptarmigan]

If the cold front comes and goes over the Gulf of Mexico, could we see something tropical spin up? I know that has happened in the past, like Hurricane Alicia.

[Stratton20]

Um Nam 00z 3k are you ok?

[Cpv17]

Um Nam 00z 3k are you ok?

It looks like more of the same to me.

[tireman4]

Read on blog or Reader
Site logo image The Eyewall
Atlantic still sputtering along with few development concerns over the next 2 weeks
By Matt Lanza on September 4, 2024

Headlines
Texas has seen extremely heavy rain with more to come, including in Louisiana through Friday.
A Caribbean tropical wave still merits watching, though any real serious risks are quite low, though it will bring heavy rain to Mexico.
The rest of the Atlantic looks quiet for the foreseeable future with a background of suppressed air likely keeping a lid on any disturbances.
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Unnamed storm system pounding Texas with heavy rain
While the Atlantic is net quiet overall, there remains the one area to monitor in the Caribbean and eventually Gulf. In fact, the whole western Gulf is a mess still with a stalled front and surface low pressure continuing to produce widespread showers and pockets of heavier rain. Some locations just north of Corpus Christi saw upwards of 8 to 9 inches of rain this morning, and heavy rain continues in some spots there.


48 hour rainfall totals have been as high as 8 to 9 inches near Aransas Pass and 3 to 7 inches over a wide area of the Texas coast. Couple this with the significant rain seen last week on the upper Texas coast and you have a major rainfall event that's unfolded. (NOAA MRMS)
The problem is that with steering currents basically collapsed here, everything has moved slowly. As I write this, there's a band of heavy rain aimed at Aransas and Calhoun Counties that has produced roughly 2 inches of rain in an hour. These bands get stuck and hit one location like this for 2 to 4 hours, leading to 4 to 8 inches of rain and flash flooding.

On top of this, we have had a persistent pattern with a stalled front in interior Texas that has led to massive rain totals of 2 to 8 inches or more across Hill Country, a place that will happily take most of this rain as prolonged drought has hammered this beautiful part of Texas. The stagnant pattern is going to begin unclogging over the next 36 hours, but not before another round of heavy rain likely impacts Louisiana and the upper Texas coast.


While interior Texas rains taper off, one more round of heavy rain is likely between Matagorda Bay and Louisiana, where 4 to 8 inches of new rainfall and flash flooding will be possible. (Pivotal Weather)
After another 4 to 8 inches is likely along the upper Texas coast and into Louisiana, this "no-named" system will probably leave some places with just shy of 15 to 20 inches of rain since last week when all is said and done.

Caribbean tropical wave remains a stubborn low risk
A cold front will sweep all this away from Texas and Louisiana over the weekend. By then, the Caribbean tropical wave we've been watching since last week should be over the Yucatan or Central America. Development odds remain about 30 percent this morning, and looking at satellite, it remains a poorly organized mass of disjointed thunderstorms south and southwest of Hispaniola today.


Showers and thunderstorms south of Jamaica and Hispaniola remain associated with a very disorganized tropical wave in the Caribbean.
As this wave moves westward, any development will be sluggish before it comes ashore in Belize or the Yucatan. From here, it remains uncertain how things will play out, but any sort of re-emergence into the Bay of Campeche would bear some watching. That said, is that the likeliest outcome? Not necessarily. Of the 51 European ensemble members, about 20 percent push this into the Bay with some development. Of the 51 members, about 5-10% maybe bring it north into the Gulf. Never tell me the odds, but I like those odds right now.


The European ensemble model is not exactly eager to bring this tropical wave back into the Bay of Campeche, but it still merits watching.
So, yes, we should continue to monitor the progress of things here of course! But as of right now, other than the ICON model, which is quite aggressive in developing this, and the European AI model, which brings it north and northeast into the central Gulf as what appears to be a subtropical storm, there is no significant model support from our traditionally best performing models for this to become a huge deal.

That said, we are looking at anywhere from about 5 to 15 inches (over 300 mm) of rainfall for portions of Mexico from this, so flooding could become an issue there.

Rest of the Atlantic is unimpressive
We continue to look for signs of life in the deep Atlantic, and while there remain two waves of note, neither appears to be a meaningful concern to anyone really.


A couple tropical waves in the deep Atlantic merit light watching, but there are no concerns for land masses at this point from either of these.
The two tropical waves in the open Atlantic have about a 10 and 20 percent chance west to east respectively of developing. The lead wave may bring some showers and storms to the islands, while the trailing wave is likely destined to go out to sea. There's nothing emerging off Africa right now, and then next wave is a few days away. That wave may have a decent chance to develop I guess, but it too looks to remain out at sea right now.

Again, there's just nothing inspiring in the Atlantic. And I'm not sure we're going to see much either. If we look at what's happening in the background of the Atlantic, we have broad sinking air dominating the western two-thirds of the basin, much as it has since early August. Any rising air has shifted from the Indian Ocean more toward Oceania and Indonesia. Sinking air tends to suppress storm development, while rising air tends to help storm development along. So, this doesn't support robust disturbances in the western Atlantic. This strongly argues that we're going to see muted activity continue through mid-month. Again, this is one of those intraseasonal signals we cannot predict in April or May that can have an outsized impact if they setup correctly. And in this case, they have certainly done so.


A complex Hovmoller plot which shows generally sinking air (red/orange) dominating in the area corresponding to the western 2/3 of the Atlantic basin.
Even a couple weeks ago, this signal seemed to indicate it would become less hostile to tropical development by early to mid-September. That's now getting kicked down the road. Unless you chase hurricanes for a living, it's hard not to be thrilled by this situation sitting here on September 4th. We'll keep an eye on things.

[tireman4]

Tropical Weather Outlook

[Scott747]

Kudos to the ICON....

I've been at 20 sustained with a few gusts over TS force. I'd guess they quickly upgrade the next TWO with an outside chance of a PTC even if it's in a 12-18 hr window.

[Stratton20]

UKMET caves to the ICON, goes south, interacts with the caribbean wave and comes back NNW toward the tex/mexico border at hour 144…. CMC rides up the border into central texas and is an absolute gully washer for SE texas, GFS not their yet, but even it is slowly starting to come on board