背风群岛东北热带风暴“加布丽埃”(07L.Gabrielle) - 西北行进，直面风切与冷涡

qiqi

AL, 92, 2025091512,   , BEST,   0, 119N,  383W,  25, 1010, DB,

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1. Central Tropical Atlantic:
A tropical wave over the central tropical Atlantic is producing a
large area of disorganized showers and thunderstorms. The
disturbance will begin to move into a more favorable environment for
development in the next couple of days, and a tropical depression 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...40 percent.
* Formation chance through 7 days...high...80 percent.

ygsj24

000
ABNT20 KNHC 151743
TWOAT

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

ygsj24

000
ABNT20 KNHC 152309
TWOAT

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:

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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ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Tue Sep 16 2025

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

1. Central Tropical Atlantic (AL92):
A large area of showers and thunderstorms continues to show signs of
organization with a broad area of low pressure located about midway
between the Windward Islands and the coast of west Africa.
Environmental conditions are conducive for further 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...80 percent.
* Formation chance through 7 days...high...90 percent.



2. Eastern Tropical Atlantic:
A tropical wave emerging off the west coast of Africa is producing
an area of disorganized showers and thunderstorms. Some slow
development of this system is possible towards the mid to latter
part of this week as it moves westward at 15 to 20 mph, moving from
the eastern to central portion of the tropical Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.

Forecaster Papin

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ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Tue Sep 16 2025

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

1. 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.



2. Eastern Tropical Atlantic:
A tropical wave emerging off the west coast of Africa is producing
an area of disorganized showers and thunderstorms. Some slow
development of this system is possible towards the mid to latter
part of this week as it moves westward at 15 to 20 mph, moving from
the eastern to central portion of the tropical Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.


Forecaster Beven

yhh

WTNT21 KNGU 161600
SUBJ/TROPICAL CYCLONE FORMATION ALERT (92L)//
RMKS/1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 13.4N 41.5W TO 17.2N 46.3W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 161200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.4N 41.5W. THE SYSTEM IS MOVING NORTHWARD AT 15 KNOTS.
2. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH. RECENT SATELLITE IMAGERY SUGGEST A DEFINED SURFACE
CIRCULATION IS DEVELOPING WITH THE AREA OF LOW PRESSURE LOCATED
MIDWAY BETWEEN THE WINDWARD ISLANDS AND WEST AFRICA. SHOWERS AND
THUNDERSTORM ACTIVITY IS STARTING TO SHOW INCREASED SIGNS OF
ORGINIZATION. A TROPICAL DEPRESSION IS LIKELY TO FORM, AS SOON AS
LATER THIS AFTERNOON. THE SYSTEM IS FORECAST TO CONTINUE MOVING
NORTHWESTWARD THROUGHOUT THE WEEK AS IS TRACKS THROUGH THE
CENTRAL ATLANTIC.
3. THIS ALERT WILL BE REISSUED, SUPERSEDED BY POTENTIAL TROPICAL
CYCLONE ADVISORY, UPGRADED TO WARNING, OR CANCELLED BY 171600Z.//

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ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Wed Sep 17 2025

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

1. Central Tropical Atlantic (AL92):
Satellite wind data indicate that the low pressure system located
about midway between the Windward Islands and the Cabo Verde Islands
is gradually becoming better defined.  In addition, the associated
shower and thunderstorm activity has become a little more
concentrated during the past several hours.  If these trends
continue, advisories could be initiated on a tropical depression
later today.  The system is expected to move generally northwestward
at 10 to 15 mph over the central tropical and subtropical Atlantic
during the next several days.  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.



2. Eastern Tropical Atlantic:
A tropical wave located a couple of hundred miles east-southeast of
the Cabo Verde Islands is producing an area of disorganized showers
and thunderstorms.  Environmental conditions are only marginally
conducive, and any development of this system should be slow to
occur while it moves westward at 15 to 20 mph across the eastern and
central portion of the tropical Atlantic.  Regardless of
development, this system will likely bring areas of heavy rain
across the Cabo Verde Islands later today and Thursday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

High Seas Forecasts issued by the National Weather Service
can be found under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

Forecaster Cangialosi

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Special Message from NHC        Wed, 17 Sep 2025 08:06:57 +0000  
NHC will initiate advisories on Tropical Depression Seven, located over the central tropical Atlantic, at 500 AM EDT (0900 UTC).

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WTNT42 KNHC 170835
TCDAT2

Tropical Depression Seven Discussion Number   1
NWS National Hurricane Center Miami FL       AL072025
500 AM AST Wed Sep 17 2025

Satellite data indicate that Invest 92L over the central tropical
Atlantic has now developed into a tropical depression.  ASCAT data
from around 00Z showed that the circulation of the system had
improved, and although it was not well defined at the time of the
pass, the system was only lacking some northerly winds on its west
side.  Since deep convection has been persisting and consolidating
near the center, it appears to now meet the convective and
circulation criteria needed to be considered a tropical cyclone.  
However, it should be noted that the system is quite large and there
is still considerable north-south elongation in the low-level
structure. The initial intensity is set at 30 kt based on a blend of
the ASCAT data and the latest Dvorak estimate from TAFB.  The
development of this system breaks a nearly 3-week streak of no
tropical cyclones in the Atlantic basin during the peak of the
hurricane season.

The depression is well away from land and roughly midway between the
Cabo Verde Islands and the Windward Islands.  The system is
estimated to be moving westward at 11 kt, but this is of low
confidence since the center has only recently formed.  A turn to the
northwest, perhaps influenced by a center formation, is expected to
occur soon as the depression moves toward a weakness in the Atlantic
subtropical ridge caused by a mid- to upper-level low to its north.  
The models show this low weakening in a day or two, which will
likely cause the cyclone to turn back to the west-northwest late
this week.  However, the system should reach the western periphery
of the ridge this weekend, resulting in a turn to the northwest or
north.  The NHC track forecast is a little to the right of the
consensus aids, giving more weight to the ECMWF and Google Deep Mind
predictions, which are faster and on the right side of the guidance.
Based on the steering pattern, and deterministic and ensemble model
solutions, there is high confidence that this system should pass
well east of the Windward and Leeward Islands.  Interests in Bermuda
should monitor forecasts of the depression over the next several
days.

Only modest strengthening is expected over the next day or two as
the depression continues to battle moderate shear from the
aforementioned low aloft and intrusions of dry air.  However, more
notable strengthening seems likely by the weekend when the system
moves into more conducive environmental conditions.  The NHC
intensity forecast shows the system reaching hurricane strength
toward the end of the period, but it should be noted that the spread
in the models at that time is significant and ranges from solutions
showing a weak low to a major hurricane.  This prediction is
generally in line with the IVCN aid.


FORECAST POSITIONS AND MAX WINDS

INIT  17/0900Z 13.7N  45.9W   30 KT  35 MPH
12H  17/1800Z 15.8N  47.4W   35 KT  40 MPH
24H  18/0600Z 17.6N  49.6W   40 KT  45 MPH
36H  18/1800Z 19.0N  51.9W   40 KT  45 MPH
48H  19/0600Z 19.7N  54.0W   45 KT  50 MPH
60H  19/1800Z 20.4N  55.9W   50 KT  60 MPH
72H  20/0600Z 21.6N  57.6W   55 KT  65 MPH
96H  21/0600Z 24.0N  60.0W   65 KT  75 MPH
120H  22/0600Z 26.9N  63.0W   75 KT  85 MPH

$$
Forecaster Cangialosi

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WTNT42 KNHC 171458
TCDAT2

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