Low Pressure Trough Over the Central Atlantic (Is Invest 99L)

[jconsor]

Given the persistent convection past 12 hours and recent increase in cyclonic turning near 10N/35W, I think this system has a decent chance (~50-60%) of becoming a TC before reaching the Lesser Antilles. However, I think the EPS members showing a hurricane from the E Caribbean to N of PR are likely overdone.

 https://twitter.com/yconsor/status/1691161088128065536




 https://twitter.com/yconsor/status/1691317204866813952




 https://twitter.com/yconsor/status/1691315522862829568




 https://twitter.com/yconsor/status/1691322129629802496




 https://twitter.com/yconsor/status/1691372242918150144




 https://twitter.com/yconsor/status/1691376653761388544




 https://twitter.com/yconsor/status/1691384643583377408

[chaser1]

A lot of conjecture with little consensus. The reasonable takeaway however is that ALL of the models are seriously waking up. Where the primary points of genesis will ultimately occur, will be key in largely defining our Atlantic season. Let's seriously hope we don't begin to see other models chiming in with GFS W. Caribbean or GOM solutions.

[Spacecoast]

0z EPS MSLP IQR Range: - shows curve N of Islands

0Z EPS: Trop Storm prob's ~10-22%

[LarryWx]

I know the CFS is inferior. But I still thought it was worth mentioning that the 0Z run has a TC form from this 8/24 near the Bahamas that then travels just off NC 8/26.

[SFLcane]

I know the CFS is inferior. But I still thought it was worth mentioning that the 0Z run has a TC form from this 8/24 near the Bahamas that then travels just off NC 8/26.

[cycloneye]

Central Tropical Atlantic:
A tropical wave is producing disorganized showers and thunderstorms
a few hundred miles west-southwest of the Cabo Verde Islands.
Development, if any, of this system should be slow to occur while
it moves generally west-northwestward at about 15 mph across the
tropical Atlantic through the end of the week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...10 percent.

[LarryWx]

Some pretty significant model news since the UKMET tends to be conservative:

-The 12Z UKMET has TCG from this in the W MDR on Fri (8/18) and it then hits the Leewards as a TS late on Saturday (8/19).
-It then moves WNW to Hispaniola on Mon (8/21) still as a TS
-It ends up near SE Bahamas as a slowly strengthening TS on Tue (8/22) moving slowly WNW and in a potentially threatening position to the Bahamas/SE US.

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS
FORECAST POSITION AT T+ 78 : 14.2N 51.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.08.2023 84 14.7N 53.5W 1005 30
1200UTC 19.08.2023 96 15.4N 57.4W 1004 34
0000UTC 20.08.2023 108 16.3N 60.5W 1003 37
1200UTC 20.08.2023 120 17.5N 63.5W 1004 40
0000UTC 21.08.2023 132 17.8N 67.0W 1004 37
1200UTC 21.08.2023 144 19.4N 68.7W 1004 38
0000UTC 22.08.2023 156 20.3N 71.2W 1004 37
1200UTC 22.08.2023 168 21.0N 72.9W 1003 39

[SFLcane]

Some pretty significant model news since the UKMET tends to be conservative:

-The 12Z UKMET has TCG from this in the W MDR on Fri (8/18) and it then hits the Leewards as a TS late on Saturday (8/19).
-It then moves WNW to Hispaniola on Mon (8/21) still as a TS
-It ends up near SE Bahamas as a slowly strengthening TS on Tue (8/22) moving slowly WNW and in a potentially threatening position to the Bahamas/SE US.

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS
FORECAST POSITION AT T+ 78 : 14.2N 51.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.08.2023 84 14.7N 53.5W 1005 30
1200UTC 19.08.2023 96 15.4N 57.4W 1004 34
0000UTC 20.08.2023 108 16.3N 60.5W 1003 37
1200UTC 20.08.2023 120 17.5N 63.5W 1004 40
0000UTC 21.08.2023 132 17.8N 67.0W 1004 37
1200UTC 21.08.2023 144 19.4N 68.7W 1004 38
0000UTC 22.08.2023 156 20.3N 71.2W 1004 37
1200UTC 22.08.2023 168 21.0N 72.9W 1003 39

[Blown Away]

Some pretty significant model news since the UKMET tends to be conservative:

-The 12Z UKMET has TCG from this in the W MDR on Fri (8/18) and it then hits the Leewards as a TS late on Saturday (8/19).
-It then moves WNW to Hispaniola on Mon (8/21) still as a TS
-It ends up near SE Bahamas as a slowly strengthening TS on Tue (8/22) moving slowly WNW and in a potentially threatening position to the Bahamas/SE US.

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS
FORECAST POSITION AT T+ 78 : 14.2N 51.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.08.2023 84 14.7N 53.5W 1005 30
1200UTC 19.08.2023 96 15.4N 57.4W 1004 34
0000UTC 20.08.2023 108 16.3N 60.5W 1003 37
1200UTC 20.08.2023 120 17.5N 63.5W 1004 40
0000UTC 21.08.2023 132 17.8N 67.0W 1004 37
1200UTC 21.08.2023 144 19.4N 68.7W 1004 38
0000UTC 22.08.2023 156 20.3N 71.2W 1004 37
1200UTC 22.08.2023 168 21.0N 72.9W 1003 39

https://i.postimg.cc/85MGPh7k/hhh.jpg

Not a great spot for a developing strong TS moving WNW...

[LarryWx]

Some pretty significant model news since the UKMET tends to be conservative:

-The 12Z UKMET has TCG from this in the W MDR on Fri (8/18) and it then hits the Leewards as a TS late on Saturday (8/19).
-It then moves WNW to Hispaniola on Mon (8/21) still as a TS
-It ends up near SE Bahamas as a slowly strengthening TS on Tue (8/22) moving slowly WNW and in a potentially threatening position to the Bahamas/SE US.

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 78 HOURS
FORECAST POSITION AT T+ 78 : 14.2N 51.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 19.08.2023 84 14.7N 53.5W 1005 30
1200UTC 19.08.2023 96 15.4N 57.4W 1004 34
0000UTC 20.08.2023 108 16.3N 60.5W 1003 37
1200UTC 20.08.2023 120 17.5N 63.5W 1004 40
0000UTC 21.08.2023 132 17.8N 67.0W 1004 37
1200UTC 21.08.2023 144 19.4N 68.7W 1004 38
0000UTC 22.08.2023 156 20.3N 71.2W 1004 37
1200UTC 22.08.2023 168 21.0N 72.9W 1003 39

https://i.postimg.cc/85MGPh7k/hhh.jpg

[url]https://i.postimg.cc/mZqbNgsG/Ukmet.jpg [/url]
Not a great spot for a developing strong TS moving WNW...

But the 12Z Euro like the GFS has just about nothing.

[SFLcane]

https://i.postimg.cc/85MGPh7k/hhh.jpg

[url]https://i.postimg.cc/mZqbNgsG/Ukmet.jpg [/url]
Not a great spot for a developing strong TS moving WNW...

But the 12Z Euro like the GFS has just about nothing.

Also has no ridge while the ukmet does.

[lsuhurricane]

Larry,

Are we sure that the 12z Euro isnt tracking this same feature, just at a lower latitude?

For reference:



All of these waves are getting confusing

[Blown Away]

Euro starting to act like the GFS with these competing low's in a big gyre.

[LarryWx]

Larry,

Are we sure that the 12z Euro isnt tracking this same feature, just at a lower latitude?

For reference:

https://i.ibb.co/k6q1CYc/9-km-ECMWF-Global-Pressure-Caribbean-850-h-Pa-Rel-Vorticity-1.gif

All of these waves are getting confusing

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the widespread 2" of qpf in and near the LAs from this that it has some "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise them to 30%.

[Blown Away]

Larry,

Are we sure that the 12z Euro isnt tracking this same feature, just at a lower latitude?

For reference:

https://i.ibb.co/k6q1CYc/9-km-ECMWF-Global-Pressure-Caribbean-850-h-Pa-Rel-Vorticity-1.gif

All of these waves are getting confusing

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the 2" of qpf in the LAs from this that it has done "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise it to 30%.

Larry,
The Euro pulls the TW out of the Caribbean over FL, Ukmet at 168 hrs is at 21.0/72.9. Same feature just Euro is S of Ukmet? Correct?

[LarryWx]

Larry,

Are we sure that the 12z Euro isnt tracking this same feature, just at a lower latitude?

For reference:

https://i.ibb.co/k6q1CYc/9-km-ECMWF-Global-Pressure-Caribbean-850-h-Pa-Rel-Vorticity-1.gif

All of these waves are getting confusing

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the 2" of qpf in the LAs from this that it has done "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise it to 30%.

[url]https://i.postimg.cc/66hx4thB/7175ffe8-b5c2-4c97-80e7-f5f494df535b.gif [/url]
Larry,
The Euro pulls the TW out of the Caribbean over FL, Ukmet at 168 hrs is at 21.0/72.9. Same feature just Euro is S of Ukmet? Correct?

Yes, it looks like the same feature to me (more southern route).

[SFLcane]

Larry,

Are we sure that the 12z Euro isnt tracking this same feature, just at a lower latitude?

For reference:

https://i.ibb.co/k6q1CYc/9-km-ECMWF-Global-Pressure-Caribbean-850-h-Pa-Rel-Vorticity-1.gif

All of these waves are getting confusing

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the 2" of qpf in the LAs from this that it has done "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise it to 30%.

[url]https://i.postimg.cc/66hx4thB/7175ffe8-b5c2-4c97-80e7-f5f494df535b.gif [/url]
Larry,
The Euro pulls the TW out of the Caribbean over FL, Ukmet at 168 hrs is at 21.0/72.9. Same feature just Euro is S of Ukmet? Correct?

Huge upper level low there on the euro not really a tc. Lots of rain for florida perhaps

[Blown Away]

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the 2" of qpf in the LAs from this that it has done "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise it to 30%.

[url]https://i.postimg.cc/66hx4thB/7175ffe8-b5c2-4c97-80e7-f5f494df535b.gif [/url]
Larry,
The Euro pulls the TW out of the Caribbean over FL, Ukmet at 168 hrs is at 21.0/72.9. Same feature just Euro is S of Ukmet? Correct?

Huge upper level low there on the euro not really a tc. Lots of rain for florida perhaps

12z Euro has our Central Atlantic TW in the Bahamas...

[LarryWx]

Yes, the Euro (and the JMA, too, among others) is tracking the same feature. What I mean by the 12Z Euro having just about nothing is that it has no surface circulation although it has trackable 850 mb vorticity further south. This leads to a very weak low over FL at 240.

The JMA has only a weak reflection at the surface (no circ), but it is a little stronger than the prior 12Z run and pretty much takes the UKMET track from the LAs to the SE Bahamas. You can tell from the 2" of qpf in the LAs from this that it has done "oomph" so to speak.

Ever since the August 4th EPS runs, this feature has had some model support and it absolutely needs a bear watch! Yet, the NHC still has TCG chances at only 10%. I'd raise it to 30%.

[url]https://i.postimg.cc/66hx4thB/7175ffe8-b5c2-4c97-80e7-f5f494df535b.gif [/url]
Larry,
The Euro pulls the TW out of the Caribbean over FL, Ukmet at 168 hrs is at 21.0/72.9. Same feature just Euro is S of Ukmet? Correct?

Huge upper level low there on the euro not really a tc. Lots of rain for florida perhaps

Not a TC over FL then on the Euro, but the upper low is pulling in moisture/moving lower level vorticity from the Caribbean into it as it looks to me.

[LarryWx]

The 12Z EPS still is active with this AEW with ~half the members having TCG though there are fewer H vs the prior run. While having fewer H, it actually is more threatening further west because the tracks are on average further SW with many more going across the LAs and then a good portion of those going well into the Caribbean followed by either dissipation or moving over Hisp/Cuba followed by Bahamas. Some though move NW toward Virgin Islands/PR followed mostly by E of the Bahamas. A few still recurve before the Caribbean and then threaten Bermuda.

Bottom line for 12Z EPS vs 0Z: not as many H but centered closer to the US over Bahamas vs 0Z's mainly E of the Bahamas to Bermuda.