2024 Atlantic Hurricane Season

[GaWx]

For 40% AEW:

12Z ICON has a strengthening cat 2 H at 180 hrs 100 miles SE of D.R. moving NW toward there

[GaWx]

More 12Z for 40% AEW: 

-UKMET (goes through 180) still has no TC from this

-GFS: back to nothing of note at sfc through Caribbean after 0Z and especially 6Z had something

-GEFS: quietest run since 12Z yesterday but still has at least ~6 solid TCs

-CMC is still not completely out as of 2:05PM (evidently Mr. Slowsky is running it today): at 210 is a cat 1 H moving NW toward W Cuba

-Euro 240: halfway between Grand Cayman and Isle of Youth at 1003 mb moving slowly NW

[GaWx]

12Z:

-Euro ensemble for 40% AEW: very active with many landfalls CONUS, especially LA to FL Gulf, SE FL, and NC

-Slowsky CMC finally finished 2.5 hours late: Cat 1 in SE Gulf moving NW

-JMA 1008 low moving WNW just SE of Grand Cayman at end (192)

 

[WxWatcher007]

25 minutes ago, GaWx said:

12Z:

-Euro ensemble for 40% AEW: very active with many landfalls CONUS, especially LA to FL Gulf, SE FL, and NC

-Slowsky CMC finally finished 2.5 hours late: Cat 1 in SE Gulf moving NW

-JMA 1008 low moving WNW just SE of Grand Cayman at end (192)

 

I’m guessing it’ll be a waffling signal for genesis the next few days as the models struggle with what’ll come out of the MT, If anything, but the environment ahead looks quite favorable should something actually try to form before the Antilles. 

[MJO812]

Gfs and AI Euro 

[WxWatcher007]

21 hours ago, Windspeed said:

This same AEW is now SSE of the Cabo Verdes and remains quite convectively active. No surprise that global ensemble suites are now picking it up. Regardless if we get development out of the western MDR from monsoonal trough breakdown, it does appear this new wave in the eastern MDR may have enough organization to develop. Future track may lead into the central Atlantic however. As of current time, the 7-day outlook from the NHC has yet to mention it. But if the wave continues to remain convectively active, it wouldn't surprise me to see it show up on the 2AM. As mentioned before, this AEW appears to have an embedded low at the surface. There is also a beefy 700 hPa easterly jet incoming from interior Africa, but the AEW may be able to stay out in front of this feature with a mid-level trough digging to the NNE. I like this system and I do think we will get TCG sometime over the weekend as environmental conditions should remain condusive.

Tagged with a lemon now. 

[MJO812]

[WxWatcher007]

The operational models on balance today have latched onto a TC genesis signal for something near the Antilles/Caribbean via the monsoon trough. This is the NHC designated orange.

The 18z Euro is faster and more robust with development through 90.

Still, I’d caution that monsoon trough TC genesis is very difficult to predict and get right, so there could still be a waffling signal over the next day or two. However, given that I believe the primary reason for a “lid” in the basin so far has been stability/SAL/northern extent of past waves, we have legitimate reasons to believe genesis is possible.

First, shear is relatively low in the zone where genesis is most likely, which has been a characteristic of the season thus far. 

Second, in this area further west, we have additional instability and a highly favorable SST/OHC profile. This is still in sharp contrast to the eastern MDR, which has seen a substantial rise in instability, but is still well below normal climo due to what’s been discussed the last few pages.

I can’t overstate how important I think it is to have the MT south and possible development in the central portion of the MDR. This keeps potential development away from the greatest influence of SAL, as you can see below. Still, it’ll be important to watch convective trends the next 48 hours. No convection, no early development. 

 

You can see the MT easily with the ribbon of convection south of the SAL above, and below you can see how there’s already elongated modest low level vorticity.

What breaks off and where will matter for the future, but for now, we just watch for convective activity and signs of vorticity consolidation. 

[GaWx]

1 hour ago, WxWatcher007 said:

The operational models on balance today have latched onto a TC genesis signal for something near the Antilles/Caribbean via the monsoon trough. This is the NHC designated orange.

The 18z Euro is faster and more robust with development through 90.

Still, I’d caution that monsoon trough TC genesis is very difficult to predict and get right, so there could still be a waffling signal over the next day or two. However, given that I believe the primary reason for a “lid” in the basin so far has been stability/SAL/northern extent of past waves, we have legitimate reasons to believe genesis is possible.

First, shear is relatively low in the zone where genesis is most likely, which has been a characteristic of the season thus far. 

Second, in this area further west, we have additional instability and a highly favorable SST/OHC profile. This is still in sharp contrast to the eastern MDR, which has seen a substantial rise in instability, but is still well below normal climo due to what’s been discussed the last few pages.

I can’t overstate how important I think it is to have the MT south and possible development in the central portion of the MDR. This keeps potential development away from the greatest influence of SAL, as you can see below. Still, it’ll be important to watch convective trends the next 48 hours. No convection, no early development. 

 

You can see the MT easily with the ribbon of convection south of the SAL above, and below you can see how there’s already elongated modest low level vorticity.

What breaks off and where will matter for the future, but for now, we just watch for convective activity and signs of vorticity consolidation. 

I’m curious. What’s the difference between the MT and the ITCZ? It appears to me that when you refer to MT that you may also be referring to the ITCZ. Going way back to John Hope on TWC, I remember him often referring to the ITCZ as the latitudinal band of clouds (typically at or N of 10N in the MDR). But I don’t recall ever hearing him call it the MT. Are they essentially one and the same? If they are, why is it called two different things?

[GaWx]

Today’s Euro Weeklies update: significantly more active than run from 2 days back

9/2-8: 60%/norm 15/ACE =9 (was 6 two days ago)
9/9-15: 80%/norm 16/ACE = 13 (was 8 two days ago)
9/16-22: 80%/norm 13/ACE = 10 (was 9 two days ago)
9/23-29: 150%/norm 10/ACE = 15 (was 12 two days ago)

-So, the 4 week period has risen from two days ago’s 35 (65% of normal) to 47 today (87% of normal).

-It not only has incorporated anticipated increased near term activity, but has also increased week 4

-Since week 4 was first released two runs ago, it has been projected to be the busiest week of the 4 despite it having significantly lower normal ACE. 

-Typically, a reversion to the mean is stronger further out in time. So, a forecast for a whopping 150% of normal way out in week 4 is quite a strong signal that late Sept. is liable to be nasty. Very active wouldn’t necessarily mean high land impacts if we’re lucky, however.

[tiger_deF]

The SAL profile looks pretty dry for this time of year, but important to remember that SAL tends to hurt larger, sprawling waves more drastically than smaller waves, stringing them out and delaying or preventing discrete consolidation.
 

While our current batch of AOIs are certainly not consolidated systems, the convective patterns are more promising for development than a week ago, where diffuse, persistent convection filled the eastern Atlantic.

[Windspeed]

@WxWatcher007 The last few OP runs are trying to close off tighter vorticity out of the decaying trough remnant between 24 and 48 hrs. Deep convection begins consolidating by Saturday. In other words, if the ECMWF (and GFS a bit later into the 72 hr range) were going to verify, we shouldn't have long to wait to see signs both convectively and cyclonically in the next few days. 594 dm heights positon to the north of this potential system, therefore, as soon as vorticity ramps up with the hypothetical TC, it immediately gets kicked into the easterly steering layer on both the 12 and 18z runs and becomes a Caribbean Cruiser until late in the midrange. Eventually, the ridge breaks down, allowing a northerly turn. Furthermore, an ULAC builds over much of the Caribbean on timing with a TC moving through the region. I have to admit. The OPs are simulating one hell of a potential setup for a powerful Caribbean hurricane. All big grains of salt though until we see actually start to see when and where vorticity ramps up.

[Windspeed]

I’m curious. What’s the difference between the MT and the ITCZ? It appears to me that when you refer to MT that you may also be referring to the ITCZ. Going way back to John Hope on TWC, I remember him often referring to the ITCZ as the latitudinal band of clouds (typically at or N of 10N in the MDR). But I don’t recall ever hearing him call it the MT. Are they essentially one and the same? If they are, why is it called two different things?

Essentially, the ITCZ is a boundary of convergence at the surface between equatorial and subtropical latitudes. A trough is, by definition, a region of covergence due to lower pressures. So you may interpret the ITCZ as an elongated monsoonal trough that stretches loosely with longitude around the globe. However, in normal meteo/climo applications, we usually stay off classifying a monsoonal trough unless there is a large or very broad region of cyclonic windflow anchored to the ITCZ with many multiple competing surface vorticities. The reasons should be obvious here. We may see the ITCZ stretch over long distances, but a large embedded surface trough will bend the boundary cyclonically into it. It can also significantly enhance larger clusters of convection spreading airmass dilffluently into jet channels above 700 hPa level. Depending on size, strength, and latitudinal placement, MTs can be a nebula for spawning TCs or a deterrent.

In the case of our current central MDR disturbance, that MT is breaking down into a region of tighter vorticity within the ITCZ. Modeling is currently evolving that surface vorticity into a TC. So, in this case, the MT would be a harbinger of TC development. Whereas the large MT over the African Sahel the past month had been a deterrent for TC development due to bending the ITCZ further north in latitude and kicking AEWs into NW Africa. Hope this helps.

[WxWatcher007]

55 minutes ago, GaWx said:

I’m curious. What’s the difference between the MT and the ITCZ? It appears to me that when you refer to MT that you may also be referring to the ITCZ. Going way back to John Hope on TWC, I remember him often referring to the ITCZ as the latitudinal band of clouds (typically at or N of 10N in the MDR). But I don’t recall ever hearing him call it the MT. Are they essentially one and the same? If they are, why is it called two different things?

I kind of use them interchangeably, because they’re often “intertwined”, but this is a good explainer & visual. Pinpointing where/whether TC genesis occurs within a monsoon trough is difficult, but a monsoon trough itself tends to be a viable mechanism for TC genesis. Sometimes multiple TCs.

https://www.nhc.noaa.gov/news/20110519_tafb_unifiedSurfaceAnalysis.pdf

[yoda]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Fri Aug 30 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Central Tropical Atlantic:
A tropical wave over the central Tropical Atlantic continues to 
produce disorganized showers and thunderstorms that are a little 
more concentrated near its axis. Environmental conditions appear 
conducive for gradual development of this system, and a tropical 
depression could form by early next week while it moves westward at 
10 to 15 mph, approaching the Lesser Antilles. The system is then 
forecast to continue moving westward to west-northwestward across 
portions of the eastern and central Caribbean Sea by the middle 
part of next week.
* Formation chance through 48 hours...low...10 percent. 
* Formation chance through 7 days...medium...50 percent.

2. Eastern Tropical Atlantic:
Another tropical wave just west of the coast of Africa is 
currently associated with an area of disorganized showers and 
thunderstorms. Some slow development of this system is possible 
through the middle portion of next week as it moves slowly to the 
west-northwest or northwest over the Eastern Tropical Atlantic. 
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.


Forecaster Beven

[ldub23]

Onto OCT. Delayed  but  not denied!!! The  lid will come  off. The switch will flip. We are still above  normal ace!!

[GaWx]

5 hours ago, ldub23 said:

Onto OCT. Delayed  but  not denied!!! The  lid will come  off. The switch will flip. We are still above  normal ace!!

We skipped all of Sep already? Wow, time really does fly more and more as we get older! 

Did you see the still pretty active 0Z EPS?

 And just for a reminder about yesterday’s Euro Weeklies’ very active late Sept prog:

9/23-29: 150%/norm 10/ACE = 15 (was 12 two days ago)

 That said, you could end up right for all anyone knows.

[TPAwx]

Interesting data.  Not only has Tampa avoided a major since 1921, we haven’t experienced sustained hurricane force winds since 1946.

https://x.com/CC_StormWatch/status/1829345028109410766

 

[GaWx]

6 hours ago, yoda said:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Fri Aug 30 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Central Tropical Atlantic:
A tropical wave over the central Tropical Atlantic continues to 
produce disorganized showers and thunderstorms that are a little 
more concentrated near its axis. Environmental conditions appear 
conducive for gradual development of this system, and a tropical 
depression could form by early next week while it moves westward at 
10 to 15 mph, approaching the Lesser Antilles. The system is then 
forecast to continue moving westward to west-northwestward across 
portions of the eastern and central Caribbean Sea by the middle 
part of next week.
* Formation chance through 48 hours...low...10 percent. 
* Formation chance through 7 days...medium...50 percent.

2. Eastern Tropical Atlantic:
Another tropical wave just west of the coast of Africa is 
currently associated with an area of disorganized showers and 
thunderstorms. Some slow development of this system is possible 
through the middle portion of next week as it moves slowly to the 
west-northwest or northwest over the Eastern Tropical Atlantic. 
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.


Forecaster Beven

At 8AM, the NHC TWO reduced the central AEW’s chances from 10/50 to 0/40. The E ATL AEW remains at 0/20.

 The 0Z EPS had a significant number of worrisome tracks for the CONUS fwiw.

[GaWx]

10 (20%) of 6Z EPS members are 990 mb or lower in the Caribbean at 144 hrs! That compares to only 6 on the active 0Z at 150 and is the same as the 10 (20%) of yesterday’s 12Z at 162.

[WxWatcher007]

2 hours ago, GaWx said:

10 (20%) of 6Z EPS members are 990 mb or lower in the Caribbean at 144 hrs! That compares to only 6 on the active 0Z at 150 and is the same as the 10 (20%) of yesterday’s 12Z at 162.

While the models continue to waffle some, the region continues to look convectively active and maybe trying to consolidate some.

925mb vorticity loop

https://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8vor5/wg8vor5_loop.html

[FredRed]

Has anyone else been playing around with Claude Sonnet 3.5 for crafting websites or apps, specifically for weather data? I've got to say, it's pretty mind-blowing. I managed to whip up a site without writing a single line of code myself – just some strategic copy-pasting from Claude.  Took about 2 days to build from scratch.

I've only tested it on Netlify so far, but I'm eager for your thoughts. What could I tweak to make it even better? The beauty is, I can just ask Claude in plain English to refine it!

Check out my project here: https://atcfmodeltracks.netlify.app/  (hopefully it will work for you).I'm more than happy to share the code here. Keep in mind, I've never written a line of HTML/JS/CSS, so there's definitely room for improvement. After all, an AI built it!

Can't imagine what IRL meteorologists will be building with this.

[klw]

A little surprised to see the convection in the Bahama area didn't even make the Tropical Discussion.

[WxWatcher007]

35 minutes ago, klw said:

A little surprised to see the convection in the Bahama area didn't even make the Tropical Discussion.

Seems more upper level for now and it’s in an area of high shear. If it gets to the Gulf time would probably be a limiting factor. 

[wthrmn654]

So gfs 12z unless I'm missing something, only shows 1 tropical thing, that's in the Gulf the entire run.  Or am I wrong, I'm working so not fully looking at it

 

[WxWatcher007]

Just now, wthrmn654 said:

So gfs 12z unless I'm missing something, only shows 1 tropical thing, that's in the Gulf the entire run.  Or am I wrong, I'm working so not fully looking at it

 

That’s the current NHC orange. 

It should be noted though that the NHC has tagged that surface trough near the TX coast with 20% 7 day odds. Models have played with the signal, but it’s all dependent on whether it drifts inland—which it does on most models. On the ones where it stays offshore like the ICON, it develops some. 

[GaWx]

It is important for folks to not hang onto longer range operational solutions whether strong ( like in this case) or weak (like in most other cases). But *fwiw* the 12Z Euro has a cat 2 moving NNW in the south central GOM at 240.

[GaWx]

36 minutes ago, WxWatcher007 said:

That’s the current NHC orange. 

It should be noted though that the NHC has tagged that surface trough near the TX coast with 20% 7 day odds. Models have played with the signal, but it’s all dependent on whether it drifts inland—which it does on most models. On the ones where it stays offshore like the ICON, it develops some. 

Northwestern Gulf of Mexico:
A surface trough of low pressure over the northwestern Gulf of
Mexico is producing a large area of disorganized showers and
thunderstorms along and just offshore the coasts of Texas and
Louisiana. This system is expected to meander near the coast
through much of next week, and some slow development is possible if
it remains offshore. Regardless of development, heavy rains could
cause some flash flooding across portions of coastal Louisiana and
the upper Texas coast during the next few days.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

 This could be one of those cases when the NHC is behind when they then up the %s quickly with each TWO and before you know it is a cherry. But it obviously still remains to be seen if this is going to develop. It wouldn’t surprise me if it did. They’re probably too low with 10%/20%.

[GaWx]

For the 40% AEW, I see some scary 12Z EPS members slamming FL from the Gulf. But others go into the W gulf, some stay just east offshore, and some still don’t even have a TC. So, I’d call it a mixed bag of possibilities.

[Normandy]

New GFS crushes Texas.  Might be times for a thread