Tropical Wave in the Central Atlantic (Is Invest 93L)

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Sep 21 2025

Eastern and Central Tropical Atlantic:
A tropical wave over the eastern Atlantic is producing disorganized
shower and thunderstorm activity well west-southwest of the Cabo
Verde Islands. Although development is unlikely during the next
couple of days, environmental conditions should gradually become
more favorable for slow development of this disturbance by the
middle to latter part of this week while it moves west-northwestward
to northwestward across the central Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...30 percent.



Forecaster Kelly

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sun Sep 21 2025

Central Tropical Atlantic:
A broad tropical wave moving into the central tropical Atlantic
continues to produce disorganized shower and thunderstorms well to
the west-southwest of the Cabo Verde Islands. Although environmental
conditions are not favorable for initial development of this system
over the next day or two, these conditions should gradually become
more favorable for development by the middle to latter part of this
week, and a tropical depression could form while the system moves
west-northwestward to northwestward across the central Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...medium...40 percent.

$$
Forecaster Papin

[TomballEd]

The delayed genesis increases the risks of a Caribbean/CONUS impact. Gabrielle (which is still just a tropical storm, at least until the next recon) is recurving quickly enough that it may not leave a break in the ridge for this to follow, especially if this is not yet a deep system. Broad turning visible but currently a small moist pocket in the desert. I'm a little confused, the pooling of mid level humidity that becomes the storm occurs ahead of the original system in a band of high ML humidity that extends from the exiting Gabrielle.

[TomballEd]

If anyone has the control run of the GFS ensembles, is it also east of the operational? That would suggests differing resolutions produce a different solution. I ask because op GFS is on the W edge of the ensembles with the New England near miss.

[cycloneye]

2 PM.

Central Tropical Atlantic:
A broad tropical wave in the central tropical Atlantic is producing
limited showers and thunderstorms well to the west-southwest of the
Cabo Verde Islands. Although environmental conditions are not
favorable for initial development of this system over the next day
or two, these conditions should gradually become more favorable for
development by the middle to latter part of this week, and a
tropical depression could form while the system moves
west-northwestward to northwestward across the central Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...medium...50 percent.

[LarryWx]

12Z UKMET:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 102 HOURS
FORECAST POSITION AT T+102 : 20.7N 59.6W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 26.09.2025 108 20.9N 59.8W 1010 36
1200UTC 26.09.2025 120 21.5N 60.5W 1008 35
0000UTC 27.09.2025 132 22.4N 60.7W 1005 41
1200UTC 27.09.2025 144 23.2N 60.9W 1002 40
0000UTC 28.09.2025 156 24.8N 61.5W 999 42
1200UTC 28.09.2025 168 26.1N 62.8W 996 44

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sun Sep 21 2025

Central Tropical Atlantic:
A broad tropical wave in the central tropical Atlantic is producing
limited showers and thunderstorms well to the west-southwest of the
Cabo Verde Islands. Although dry air should prevent any significant
development over the next day or two, environmental conditions
should gradually become more favorable for development by the middle
to latter part of this week, and a tropical depression could form
while the system moves west-northwestward to northwestward across
the central Atlantic.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...medium...60 percent.

[MEANINGLESS_NUMBERS]

EPS brings many members over Bermuda.

[cycloneye]

Central Tropical Atlantic:
Shower and thunderstorm activity associated with a tropical wave
located about midway between the Lesser Antilles and the Cabo Verde
Islands has increased since yesterday. Environmental conditions
are forecast to become more favorable for development by tomorrow,
and a tropical depression is likely to form by the middle to latter
part of this week while while the system moves west-northwestward
to northwestward across the central Atlantic.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...high...70 percent.

[LarryWx]

12Z UKMET threatens Bermuda:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 90 HOURS
FORECAST POSITION AT T+ 90 : 22.0N 61.0W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 26.09.2025 96 22.5N 61.5W 1010 35
0000UTC 27.09.2025 108 22.5N 62.5W 1008 37
1200UTC 27.09.2025 120 23.1N 63.5W 1007 38
0000UTC 28.09.2025 132 23.7N 64.1W 1005 45
1200UTC 28.09.2025 144 24.5N 66.1W 1003 41
0000UTC 29.09.2025 156 25.6N 66.8W 1000 43
1200UTC 29.09.2025 168 27.2N 66.4W 997 45

[Teban54]

I continue to be amazed at how quiet this thread is, given the intensities on many global models. Perhaps people have already season canceled?

All non-GFS operational models have been showing a Gabrielle redux:

0z ECMWF: A cleanly tropical peak is 975 mb. (It gets down to 957 mb later, but with extratropical transition already started while doing a Fiona-esque slam into Nova Scotia.)



12z ICON: Peak 951 mb.



12z CMC: Peak 982 mb. (CMC pressures are usually very conservative - it shows Gabrielle as 994 mb now when it's actually in the 950s.)



All three operational models have been developing this wave, with significant deepening in the subtropics, for a few runs now. GFS is the only one that lacks consistency, as it favors the 10/40 AOI to the west.

[cycloneye]

2 PM.

Central Tropical Atlantic:
Shower and thunderstorm activity associated with a tropical wave
located about midway between the Lesser Antilles and the Cabo Verde
Islands continues to increase. Environmental conditions are
forecast to become more favorable for development by tomorrow,
and a tropical depression is likely to form on Wednesday or
Thursday while the system moves west-northwestward to
northwestward across the central Atlantic.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...high...80 percent

[BobHarlem]

12z Euro, over Bermuda as a 954mb major.



(Also develops the other area as a landfall in NC as a TD/TS)

[TomballEd]

Too close to each other? While the cherry looks better organized, the orange looks to be in a position to enhance shear on the cherry. Orange has farther to go to become a TC but it may stop the cherry from organizing all together.

[Sciencerocks]

[Teban54]

https://imagizer.imageshack.com/img924/7856/uKQAb9.gif

This actually shows the wave coming together nicely, more so than you would expect.

[Pelicane]

https://imagizer.imageshack.com/img924/7856/uKQAb9.gif

This actually shows the wave coming together nicely, more so than you would expect.

The GFS is probably underestimating this wave. All of the models currently support it, even the AI models. Not sure why it's not seeing it.

[ScottNAtlanta]

https://imagizer.imageshack.com/img924/7856/uKQAb9.gif

This actually shows the wave coming together nicely, more so than you would expect.

The GFS is probably underestimating this wave. All of the models currently support it, even the AI models. Not sure why it's not seeing it.

On the other hand...the euro shear forecast would imply this wave should NOT develop. It has substantial shear in a couple of days over this while the western wave is shown to be in light shear, so I don't know why the euro wants to develop it. It seems like the 2 products are saying very different things

[chaser1]

I continue to be amazed at how quiet this thread is, given the intensities on many global models. Perhaps people have already season canceled?

I don't think the thread is quiet because most members are unaware of present activity. I think the quiet is primarily connected to lack of impact risk. Thus far this season we are primarily seeing a poleward recurvature storm track pattern in place. As we approach October its increasingly likely that additional Central Atlantic development will be apt to recurve as well. I doubt we'll see this board light up until a potential threat to the Caribbean, GOM, CONUS, or Canadian Seaboard occurs. That or, something else extraordinary.

[ConvergenceZone]

I continue to be amazed at how quiet this thread is, given the intensities on many global models. Perhaps people have already season canceled?

I don't think the thread is quiet because most members are unaware of present activity. I think the quiet is primarily connected to lack of impact risk. Thus far this season we are primarily seeing a poleward recurvature storm track pattern in place. As we approach October its increasingly likely that additional Central Atlantic development will be apt to recurve as well. I doubt we'll see this board light up until a potential threat to the Caribbean, GOM, CONUS, or Canadian Seaboard occurs. That or, something else extraordinary.

I agree, out to sea storms don't usually interest most tropic enthusiasts here, thus the lack of posts. But of course we have to think of Bermuda at this point. Hopefully it will be in the clear.