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Tropical Storm Gabrielle

WxWatcher007

By WxWatcher007,
in Tropical Headquarters

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WxWatcher007

WxWatcher007

Posted
Posted

The Atlantic has been exceptionally quiet for a second consecutive September, but it looks as if the basin is trying to wake back up with a robust tropical wave heading through the tropical Atlantic. 

giphy.gif

The wave, focused near 30W, is most likely still a few days away from consolidating and kicking off the process of tropical genesis, but with a strong model signal from operational/ensemble/AI models, and the wave producing much more convection than the failed development of 91L, this one looks like it will become a TC eventually. 

There are still some headwinds, figuratively and literally. In the image above you can see stable air to the northwest of the wave. Further west, there is wind shear evident with what little convection being blown over. Long term though, once this wave is able to consolidate, it will have a chance to intensify. 

Long way away from that however. 

wYnj2bE.png

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GaWx

GaWx

Posted
Posted

12Z runs regarding this MDR AOI:

-GFS/CMC/Icon all have this eventually as a H with GFS/CMC both recurving well E of Bermuda (Icon doesn’t go out far enough to tell)


-JMA has this as a TD at 48 and a TS at 72. This is stronger than the two prior 12Z runs that each had it as only a TD.

-Euro has a MH passing just SE of Bermuda

-UKMET again has this as a TS. This is a bit further W than recent runs but it’s still aiming a bit E of Bermuda as of 168:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 72 HOURS
FORECAST POSITION AT T+ 72 : 16.4N 47.4W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 17.09.2025 72 16.4N 47.4W 1006 40
0000UTC 18.09.2025 84 17.7N 48.8W 1006 42
1200UTC 18.09.2025 96 19.5N 52.1W 1006 44
0000UTC 19.09.2025 108 20.6N 54.3W 1006 40
1200UTC 19.09.2025 120 22.8N 55.1W 1006 44
0000UTC 20.09.2025 132 23.1N 57.0W 1005 43
1200UTC 20.09.2025 144 25.1N 57.7W 1003 46
0000UTC 21.09.2025 156 26.3N 58.6W 1001 49
1200UTC 21.09.2025 168 28.3N 59.3W 999 48

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GaWx

GaWx

Posted
Posted

0Z runs

-are fairly similar to the 12Z for the Icon, GFS, and CMC

-This time the UKMET is even further W and threatens Bermuda:

0Z UK: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 72 HOURS
FORECAST POSITION AT T+ 72 : 18.0N 48.8W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 18.09.2025 72 18.0N 48.8W 1008 38
1200UTC 18.09.2025 84 20.0N 51.3W 1007 42
0000UTC 19.09.2025 96 21.2N 53.2W 1007 38
1200UTC 19.09.2025 108 22.7N 55.1W 1008 30
0000UTC 20.09.2025 120 22.5N 57.2W 1008 32
1200UTC 20.09.2025 132 23.1N 58.3W 1009 31
0000UTC 21.09.2025 144 23.3N 59.8W 1008 33
1200UTC 21.09.2025 156 23.9N 61.0W 1008 35
0000UTC 22.09.2025 168 24.3N 63.1W 1007 31

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GaWx

GaWx

Posted
Posted

12Z runs:

-GFS/CMC favoring an H but well E of Bermuda

-Euro is very close to but just NE of Bermuda with an H

-Icon is well to the SW of those other 3 and it’s fate is still unknown at 180 with it a TS S of Bermuda just starting a NW recurve

-12Z JMA out to 72 so far: TC moving NW way out there

-12Z UKMET like prior run threatens Bermuda with this run aimed only a little E of there:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 54 HOURS
FORECAST POSITION AT T+ 54 : 17.5N 46.9W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 18.09.2025 60 18.3N 47.8W 1007 41
1200UTC 18.09.2025 72 20.5N 50.5W 1007 43
0000UTC 19.09.2025 84 21.3N 53.4W 1007 41
1200UTC 19.09.2025 96 22.5N 55.5W 1007 31
0000UTC 20.09.2025 108 23.3N 57.0W 1007 32
1200UTC 20.09.2025 120 25.2N 58.1W 1007 38
0000UTC 21.09.2025 132 26.6N 58.4W 1004 44
1200UTC 21.09.2025 144 27.7N 60.4W 1002 41
0000UTC 22.09.2025 156 29.0N 61.7W 999 49
1200UTC 22.09.2025 168 30.6N 62.4W 995 51

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GaWx

GaWx

Posted
Posted
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
Issued by the NWS Weather Prediction Center College Park MD
200 PM EDT Mon Sep 15 2025

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

Central Tropical Atlantic (AL92):
A broad area of low pressure has formed roughly midway between the
Windward Islands and the coast of west Africa. This system has
become better organized since yesterday and is expected to move
through a favorable environment for further development. A
tropical depression or tropical storm is likely to form by the
middle to latter part of this week as the system moves
west-northwestward at 10 to 15 mph over the central tropical
Atlantic.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...90 percent.

$$
Forecaster Blake/Putnam
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GaWx

GaWx

Posted
Posted

Now 60/90: is the long drought about to be broken? Keep in mind though that 91L also made it to 60/90 along with strong model support and surprisingly never developed:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Sep 15 2025

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

1. Central Tropical Atlantic (AL92):
A broad area of low pressure is located about midway between
the Windward Islands and the coast of west Africa. This system
is showing signs of organization, and is expected to move through a
favorable environment for further development. A tropical
depression or tropical storm is likely to form by the middle to
latter part of this week while the system moves west-northwestward
at 10 to 15 mph over the central tropical Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...90 percent.



Forecaster Pasch

 

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WxWatcher007

WxWatcher007

Posted
  • Author
Posted
1 minute ago, GaWx said:

Now 60/90: is the long drought about to be broken? Keep in mind though that 91L also made it to 60/90 along with strong model support and surprisingly never developed:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Sep 15 2025

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

1. Central Tropical Atlantic (AL92):
A broad area of low pressure is located about midway between
the Windward Islands and the coast of west Africa. This system
is showing signs of organization, and is expected to move through a
favorable environment for further development. A tropical
depression or tropical storm is likely to form by the middle to
latter part of this week while the system moves west-northwestward
at 10 to 15 mph over the central tropical Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...90 percent.



Forecaster Pasch

 

Yeah that's in the back of my mind, but I think the distinction here is the much larger moisture envelope and ability of this one to keep up convection. Environment looks pretty favorable for development/intensification in the subtropics too, which worked well with Fernand. 

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Wannabehippie

Wannabehippie

Posted
Posted
1 hour ago, GaWx said:

Now 60/90: is the long drought about to be broken? Keep in mind though that 91L also made it to 60/90 along with strong model support and surprisingly never developed:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Sep 15 2025

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

1. Central Tropical Atlantic (AL92):
A broad area of low pressure is located about midway between
the Windward Islands and the coast of west Africa. This system
is showing signs of organization, and is expected to move through a
favorable environment for further development. A tropical
depression or tropical storm is likely to form by the middle to
latter part of this week while the system moves west-northwestward
at 10 to 15 mph over the central tropical Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...90 percent.



Forecaster Pasch

 

There was more SAL when 91L was around. That has cleared out an area, where 92L is at right now. There is still some ahead of it, and a big blob behind it. But where it is right now it is in a good spot. 92L also has a lot more convection than 91L ever had associated with it. 92L still will need to have that dry air ahead of it get out of the way, or it will fizzle out as well IMHO. No closed circulation that I can pick out with my untrained eyes.



g16split-4.jpg

 

blob:https://www.tropicaltidbits.com/75019b3b-06c8-416d-8b72-d0c8bb3da341

 

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GaWx

GaWx

Posted
Posted
1 hour ago, Coach McGuirk said:

It's a fish storm. 

Many are. And at least there’d be something interesting to follow with hopefully nobody needing to worry about potential devastation and casualties. I say hopefully nobody because there’s still some chance Bermuda will be hit. Fortunately though, Bermuda handles storms pretty well due to good elevation just off many of the beaches (hilly terrain) and very strict building codes. This includes limestone roofs! I’ve been there.

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GaWx

GaWx

Posted
Posted

8AM TWO: getting very close now…

Central Tropical Atlantic (AL92):
Showers and thunderstorms associated with a broad low pressure area
located about midway between the Windward Islands and the coast of
west Africa have become better organized since yesterday.
Environmental conditions are conducive for additional development,
and a tropical depression or storm is likely to form in the next day
or two as the system moves west-northwestward or northwestward at 10
to 15 mph over the central tropical Atlantic.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.
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Wannabehippie

Wannabehippie

Posted
Posted
5 minutes ago, GaWx said:

8AM TWO: getting very close now…

Central Tropical Atlantic (AL92):
Showers and thunderstorms associated with a broad low pressure area
located about midway between the Windward Islands and the coast of
west Africa have become better organized since yesterday.
Environmental conditions are conducive for additional development,
and a tropical depression or storm is likely to form in the next day
or two as the system moves west-northwestward or northwestward at 10
to 15 mph over the central tropical Atlantic.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

Satellite photos show an ULL dropping down, that probably will interfere with development.


blob:https://www.tropicaltidbits.com/53dc1fce-b712-4618-afb4-c94259665cca

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  • WxWatcher007 changed the title to Invest 92L--90% two day, 90% five day odds
GaWx

GaWx

Posted
Posted

 12Z UKMET: center passes just SE of Bermuda
  

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  36 HOURS
              FORECAST POSITION AT T+ 36 : 19.4N  49.2W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 18.09.2025   36  19.4N  49.2W     1008            42
    1200UTC 18.09.2025   48  20.2N  51.3W     1007            37
    0000UTC 19.09.2025   60  21.1N  53.9W     1007            33
    1200UTC 19.09.2025   72  21.6N  56.5W     1008            28
    0000UTC 20.09.2025   84  22.8N  58.1W     1008            31
    1200UTC 20.09.2025   96  24.1N  59.6W     1009            30
    0000UTC 21.09.2025  108  25.8N  59.8W     1008            37
    1200UTC 21.09.2025  120  27.3N  61.2W     1005            46
    0000UTC 22.09.2025  132  28.8N  62.3W     1003            44
    1200UTC 22.09.2025  144  30.3N  63.0W     1001            44
    0000UTC 23.09.2025  156  31.7N  63.0W     1000            49
    1200UTC 23.09.2025  168  32.5N  61.5W      998            43
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GaWx

GaWx

Posted
Posted

More 12Z runs:

 The models have switched in some cases. The GFS/CMC moved W to just SE of Bermuda whereas the Euro moved E to well E of Bermuda.

Icon: still well to the SW of others with it much weaker SSW of Bermuda then recurving NW

JMA: TS at Bermuda at 192

 

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GaWx

GaWx

Posted
Posted

8 PM TWO:

Central Tropical Atlantic (AL92):
Showers and thunderstorms associated with an elongated area of low
pressure located about midway between the Windward Islands and the
Cabo Verde Islands have changed little in organization during the
past 12 hours or so. However, environmental conditions are
conducive for additional development, and a tropical depression or
storm is expected to form in the next day or two as the system moves
west-northwestward or northwestward at 10 to 15 mph over the central
tropical Atlantic. Additional information on this system, including
gale warnings, can be found in High Seas Forecasts issued by the
National Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.
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GaWx

GaWx

Posted
Posted

 Check this out folks: 0Z GFS is much weaker with strongest at 1005 mb/barely a TS followed by it weakening and then dissipating over open water of the SW Atlantic into nothing! The prior 13 runs all had hurricanes, usually MH! What the?

—————

0Z UKMET: passes just E of Bermuda (similar to 0Z Euro): 

TROPICAL DEPRESSION 92L        ANALYSED POSITION : 14.4N  43.9W

     ATCF IDENTIFIER : AL922025

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 17.09.2025    0  14.4N  43.9W     1010            28
    1200UTC 17.09.2025   12  16.9N  45.4W     1009            33
    0000UTC 18.09.2025   24  19.5N  48.0W     1009            41
    1200UTC 18.09.2025   36  20.7N  50.6W     1008            37
    0000UTC 19.09.2025   48  21.3N  53.3W     1008            31
    1200UTC 19.09.2025   60  21.7N  55.6W     1009            27
    0000UTC 20.09.2025   72  22.0N  57.6W     1010            26
    1200UTC 20.09.2025   84  23.3N  59.0W     1010            30
    0000UTC 21.09.2025   96  24.8N  60.2W     1010            29
    1200UTC 21.09.2025  108  26.2N  60.8W     1010            32
    0000UTC 22.09.2025  120  27.5N  61.9W     1009            37
    1200UTC 22.09.2025  132  29.2N  63.5W     1010            37
    0000UTC 23.09.2025  144  31.1N  63.5W     1010            34
    1200UTC 23.09.2025  156  33.1N  62.8W     1010            33
    0000UTC 24.09.2025  168  34.0N  59.7W     1009            30
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NorthHillsWx

NorthHillsWx

Posted
Posted
7 hours ago, GaWx said:

 Check this out folks: 0Z GFS is much weaker with strongest at 1005 mb/barely a TS followed by it weakening and then dissipating over open water of the SW Atlantic into nothing! The prior 13 runs all had hurricanes, usually MH! What the?

—————

0Z UKMET: passes just E of Bermuda (similar to 0Z Euro): 

TROPICAL DEPRESSION 92L        ANALYSED POSITION : 14.4N  43.9W

     ATCF IDENTIFIER : AL922025

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 17.09.2025    0  14.4N  43.9W     1010            28
    1200UTC 17.09.2025   12  16.9N  45.4W     1009            33
    0000UTC 18.09.2025   24  19.5N  48.0W     1009            41
    1200UTC 18.09.2025   36  20.7N  50.6W     1008            37
    0000UTC 19.09.2025   48  21.3N  53.3W     1008            31
    1200UTC 19.09.2025   60  21.7N  55.6W     1009            27
    0000UTC 20.09.2025   72  22.0N  57.6W     1010            26
    1200UTC 20.09.2025   84  23.3N  59.0W     1010            30
    0000UTC 21.09.2025   96  24.8N  60.2W     1010            29
    1200UTC 21.09.2025  108  26.2N  60.8W     1010            32
    0000UTC 22.09.2025  120  27.5N  61.9W     1009            37
    1200UTC 22.09.2025  132  29.2N  63.5W     1010            37
    0000UTC 23.09.2025  144  31.1N  63.5W     1010            34
    1200UTC 23.09.2025  156  33.1N  62.8W     1010            33
    0000UTC 24.09.2025  168  34.0N  59.7W     1009            30

The GFS brings it back to life a little more on the 6z but one thing is beginning to become apparent and that is this system likely struggles until the recurve due to a combination of large size, shear, and an area of SAL it will be interacting with. To me this was a given to become a MH given modeling over the past few days. Now I am not so sure.

EDIT: GFS brings the system to the 940’s and a MH as it recurves and accelerates 

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  • WxWatcher007 changed the title to Tropical Storm Gabrielle
yoda

yoda

Posted
Posted 
BULLETIN
Tropical Storm Gabrielle Advisory Number   2
NWS National Hurricane Center Miami FL       AL072025
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Wed Sep 17 2025
 
...GABRIELLE FORMS OVER THE CENTRAL TROPICAL ATLANTIC...
...FORECAST TO REMAIN OVER OPEN WATERS FOR SEVERAL DAYS...
 
 
SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.5N 46.6W
ABOUT 1085 MI...1745 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES
 
 
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
 
 
DISCUSSION AND OUTLOOK
----------------------
At 1100 AM AST (1500 UTC), the center of poorly defined Tropical 
Storm Gabrielle was located near latitude 17.5 North, longitude 
46.6 West. Gabrielle is moving toward the north-northwest near 22 
mph (35 km/h). An erratic northwestward to west-northwestward 
motion at a reduced forward speed is anticipated across the 
tropical and subtropical central Atlantic during the next few days.
 
Satellite-derived winds indicate that the maximum sustained winds 
are near 45 mph (75 km/h) with higher gusts. Little change in 
strength is forecast during the next 48 hours but some gradual 
intensification is forecast over the weekend.
 
Tropical-storm-force winds extend outward up to 175 miles (280 km)
from the center, primarily in the eastern semicircle of the storm.
 
The estimated minimum central pressure is 1006 mb (29.71 inches).
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yoda

yoda

Posted
Posted 
Tropical Storm Gabrielle Discussion Number   2
NWS National Hurricane Center Miami FL       AL072025
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Wed Sep 17 2025

Satellite imagery this morning indicates that the large system is 
not well-organized, with an elongated circulation 
oriented from north-northwest to south-southeast containing a few 
embedded swirls.  The advisory center is a mean center of those 
swirls, with any associated convection well east of the position due 
to southwesterly shear.  While it wouldn't appear so from 
conventional satellite data, a recent scatterometer pass indicates 
upwards of 40-kt winds present, generally northeast and southeast of 
the center of circulation.  Although the system is at best 
marginally well defined, there is enough data to support an initial 
intensity of 40 kt, and the depression is named Gabrielle.  

Little strengthening is anticipated over the next 48 hours as 
Gabrielle faces an unfavorable shear environment from an 
upper-level trough and a possible center re-formation, and the 
forecast intensity remains nearly steady through Friday. By this 
weekend, a more conducive environment is anticipated, which should 
allow for gradual intensification. Gabrielle is forecast to become 
a hurricane by 96 hours. The NHC intensity forecast remains 
fairly similar to the previous forecast cycle, but it should be 
noted that there remains considerable spread in the solutions and 
overall forecast intensity confidence is low.

Gabrielle is well away from land and about midway between the Cabo 
Verde Islands and the Windward Islands.  The current estimated 
motion is north-northwestward, but this is highly uncertain as the 
center could be re-forming to the north.  The system is forecast to 
move northwestward to west-northwestward due to the subtropical 
ridge for the next several days.  While the forecast has been 
adjusted to the north from the previous one, this is almost 
exclusively due to the jump in the initial position.  This is a 
highly uncertain forecast until a better defined center forms.   
Based on the recent trends, this system should pass well east and 
north of the Windward and Leeward Islands, but interests in Bermuda 
should monitor forecasts during the next several days.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/1500Z 17.5N  46.6W   40 KT  45 MPH
 12H  18/0000Z 19.5N  48.5W   45 KT  50 MPH
 24H  18/1200Z 20.8N  50.6W   45 KT  50 MPH
 36H  19/0000Z 21.8N  52.6W   45 KT  50 MPH
 48H  19/1200Z 22.7N  54.6W   45 KT  50 MPH
 60H  20/0000Z 23.5N  56.6W   50 KT  60 MPH
 72H  20/1200Z 24.7N  58.3W   55 KT  65 MPH
 96H  21/1200Z 27.4N  60.8W   65 KT  75 MPH
120H  22/1200Z 30.0N  62.5W   75 KT  85 MPH
 
$$
Forecaster Taylor/Blake
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NorthHillsWx

NorthHillsWx

Posted
Posted
5 minutes ago, GaWx said:


 I bet Bastardi will have a thing or two to say about this upgrade lol.

I have a thing or two to say! First thing- this might take the cake as the most questionably named TS ever! Second thing- I still don’t see a defined center and they even mentioned it is marginally organized at best. I guess the assumption is it keeps organizing through the day but man that’s a questionable call with multiple circulations within a broad wave axis

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MANDA

MANDA

Posted
Posted
15 minutes ago, WxWatcher007 said:

I would’ve named yesterday before this one and that Mid-Atlantic low wasn’t even tropical lol. I guess they had to go with continuity once they declared it a depression.

They could have left it a depression at 11:00.  That would have been the better choice.  Thing is a sloppy mess.

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NorthHillsWx

NorthHillsWx

Posted
Posted

12z GFS again shows this system unraveling into an open wave in a few days. CMC and EURO continue to be much more robust. Serious spread in hurricane models still but as a whole they have trended considerably downward with the vast majority keeping the system as a tropical storm or weakening back to TS at the end of the period, interesting 

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