百慕大西南二级飓风“伊梅尔达”(09L.Imelda) - 与Humberto共舞，影响巴哈马群岛 - NHC:85KT

ygsj24

000
ABNT20 KNHC 261709
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Fri Sep 26 2025

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

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Humberto, located over the subtropical central Atlantic, and has
issued the last advisory on Post-Tropical cyclone Gabrielle over
the northeastern Atlantic.

Southwestern Atlantic (AL94):
Satellite data and surface observations indicate that a low pressure
system appears to be forming near eastern Cuba and the southeastern
Bahamas.  This system is producing a large area of disorganized
showers and thunderstorms, and gusty winds. Gradual development of
this system is expected, and it will likely become a tropical
depression during the next day or so while it moves northwestward or
northward across the central and northwestern Bahamas.  

Regardless of development, heavy rains and gusty winds are ongoing
in the Dominican Republic, Haiti, the Turks and Caicos Islands, the
southeastern Bahamas and eastern Cuba, and are likely to spread
across the remainder of the Bahamas over the weekend. Interests in
all of these areas should monitor the progress of the system.  
Tropical storm watches or warnings could be required for portions of
the Bahamas and advisories on a potential tropical cyclone could be
issued as early as later today. While there remains considerable
uncertainty in the long-range track and intensity of the system,
there is a significant risk of wind, rainfall, and storm surge
impacts for a portion of the southeast U.S. coast early next week.
Interests in this area should also monitor the progress of the
system.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

$$
Forecaster Cangialosi/Reinhart/Hagen

ygsj24

000
WTNT44 KNHC 262040
TCDAT4

Potential Tropical Cyclone Nine Discussion Number   1
NWS National Hurricane Center Miami FL       AL092025
500 PM EDT Fri Sep 26 2025

Visible satellite images and surface observations suggest that
Invest 94L is gradually organizing and beginning to develop a
low-level circulation near eastern Cuba with estimated maximum winds
of about 30 kt.  Although the system does not meet the criteria of a
tropical cyclone currently, it is expected to become one during the
next day or so.  In addition, the system is likely to bring tropical
storm conditions to portions of the central and northwestern Bahamas
this weekend and potential impacts to portions of the southeast U.S.
early next week.  Therefore, NHC is now initiating Potential
Tropical Cyclone advisories for this disturbance.

The system has been moving west-northwestward at about 8 kt during
the past 12 to 24 hours.  However, this motion is expected to change
as the disturbance is forecast to turn northward in southerly flow
between a large-scale trough over the eastern U.S. and a subtropical
ridge over the central-western Atlantic.  This track should take the
system across the central and northwestern Bahamas over the weekend.
The models are in good agreement through that time period, but they
diverge significantly early next week when the synoptic pattern
becomes complicated.  If the system moves on the fast side of the
guidance, it will likely be more influenced by the U.S. trough that
is expected to cut off.  In that scenario, the disturbance would
move inland over the southeast U.S. early next week.  Conversely, if
the system moves on the slow side of the guidance, Humberto's
circulation will cause the steering currents to collapse, resulting
in this system stalling near the southeast coast or drifting
eastward.  The NHC track forecast lies roughly between these
scenarios, in best agreement with EMXI, but confidence is very
low in the days 4 and 5 positions.

Strengthening is likely to be slow in the short term due to the
current land interaction and some southerly shear.  However, gradual
intensification seems like a good bet this weekend and on Monday
while the system tracks over the Gulf Stream and within a diffluent
upper-level wind pattern.  The NHC intensity forecast lies close to
the hurricane regional and consensus models and shows the system
reaching hurricane strength early next week.  It should be
emphasized that the long-range intensity forecast depends largely on
where the system is and the degree of land interaction at those
periods, and therefore, is of low confidence. Given the
higher-than-usual uncertainty in the forecast track and intensity of
the system, NOAA Hurricane Hunter aircraft have been collecting data
over the western Atlantic since yesterday, and additional upper-air
launches are occurring.  This data collection will continue through
the weekend to help improve the model guidance for this system.

KEY MESSAGES:

1. The disturbance is forecast to become a tropical storm this
weekend and bring tropical storm conditions to portions of the
central and northwestern Bahamas, where Tropical Storm Warnings and
Watches, respectively, have been issued. Rainfall associated with
this system will impact eastern Cuba, Hispaniola, Jamaica, and the
Bahamas through the weekend.  

2.  There is an increasing threat of heavy rainfall early next
week from coastal Georgia through the Carolinas and into the
southern Mid-Atlantic states, which could cause flash, urban, and
river flooding.

3. The system is expected to be at or near hurricane intensity
when it approaches the southeast U.S. coast early next week, where
there is a risk of storm surge and wind impacts. Residents in that
area should monitor updates to the forecast and ensure they have
their hurricane plan in place.

FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 20.9N  74.6W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
12H  27/0600Z 21.7N  75.3W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
24H  27/1800Z 22.7N  75.8W   30 KT  35 MPH...TROPICAL CYCLONE
36H  28/0600Z 24.1N  76.4W   35 KT  40 MPH
48H  28/1800Z 25.6N  76.9W   45 KT  50 MPH
60H  29/0600Z 27.4N  77.3W   55 KT  65 MPH
72H  29/1800Z 29.7N  78.0W   65 KT  75 MPH
96H  30/1800Z 31.8N  78.9W   65 KT  75 MPH
120H  01/1800Z 32.3N  79.3W   60 KT  70 MPH

$$
Forecaster Cangialosi

pocketbox

WTNT44 KNHC 270237
TCDAT4

Potential Tropical Cyclone Nine Discussion Number   2
NWS National Hurricane Center Miami FL       AL092025
1100 PM EDT Fri Sep 26 2025

Many thanks to the crew of a NOAA P-3 Hurricane Hunter aircraft,
which has been flying a surveillance mission in the disturbance this
evening.  Dropsonde data from this flight, as well as surface
observations from Cuba, suggest that the system is still a trough
of low pressure, and the trough axis is a little farther west than
previously estimated.  Maximum winds remain near 30 kt, and the
pressure has dropped slightly to 1007 mb based on the dropsonde
data.

The current motion is now estimated to be northwestward, or 305/8
kt.  The system is expected to slow down and turn
north-northwestward by Saturday morning and continue that trajectory
over the weekend, embedded in the southerly flow between a
deep-layer trough over the southeastern U.S. and a ridge over the
west-central Atlantic.  The track models are in good agreement for
the first 3 days of the forecast.  The new NHC forecast track has
been shifted westward during that period, mainly due to the
westward adjustment of the initial position, but it is also a bit
slower than the previous prediction based on the latest guidance.  
There is significantly more uncertainty in the track forecast after
day 3, but at the very least it appears that the system will slow
down considerably and perhaps even stall near the coast of South
Carolina.  Interestingly, the 18z GFS and ECMWF solutions no longer
show the system moving inland over the southeastern U.S. and have
come more in line with their respective ensemble means, as well as
the HCCA consensus aid and Google DeepMind mean.  For this new
forecast, a very slow, nearly stationary motion is shown on day 5,
with perhaps some hint of the start of a northeastward motion.  
That said, even if the system stalls just offshore, it would still
be large enough to cause wind and coastal flooding impacts along
the southeastern U.S. coast, as well as heavy rainfall/flooding
concerns in inland areas.

Global models suggest it will still take another 24 hours or so for
the system to develop a well-defined circulation and organized
convection to be classified as a tropical depression.  After that
time, strengthening is expected while the system moves over very
warm waters and within a divergent upper-level environment.  The
NHC forecast continues to show the system reaching hurricane
strength in 3-4 days, which is close to the HCCA and IVCN consensus
aids.  Stronger shear, and possibly the beginnings of an
interaction with a nearby frontal boundary, could cause some
weakening by day 5.


KEY MESSAGES:

1. The disturbance is forecast to become a tropical storm this
weekend and bring tropical storm conditions to portions of the
central and northwestern Bahamas, where Tropical Storm Warnings and
Watches, respectively, are in effect. Rainfall associated with
this system will impact eastern Cuba, Hispaniola, Jamaica, and the
Bahamas through the weekend.

2.  There is an increasing threat of heavy rainfall early next
week from coastal Georgia through the Carolinas and into the
southern Mid-Atlantic states, which could cause flash, urban, and
river flooding.

3. The system is expected to be at or near hurricane intensity
when it approaches the southeast U.S. coast early next week, where
there is a risk of storm surge and wind impacts. Residents in that
area should monitor updates to the forecast and ensure they have
their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 21.5N  76.0W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
12H  27/1200Z 22.2N  76.6W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
24H  28/0000Z 23.3N  77.0W   30 KT  35 MPH...TROPICAL CYCLONE
36H  28/1200Z 24.8N  77.5W   35 KT  40 MPH
48H  29/0000Z 26.3N  77.9W   45 KT  50 MPH
60H  29/1200Z 28.2N  78.3W   55 KT  65 MPH
72H  30/0000Z 30.1N  78.9W   65 KT  75 MPH
96H  01/0000Z 32.0N  79.2W   65 KT  75 MPH
120H  02/0000Z 32.4N  78.7W   55 KT  65 MPH

$$
Forecaster Berg

pocketbox

WTNT44 KNHC 270843
TCDAT4

Potential Tropical Cyclone Nine Discussion Number   3
NWS National Hurricane Center Miami FL       AL092025
500 AM EDT Sat Sep 27 2025

Satellite imagery this morning shows an increase in vorticity at
the western edge of a convective cluster located near the Ragged
Islands in the Bahamas. However, this has not reached the stage
where it could be called a well-defined center of circulation.  
Based on this, the system is continued as a potential tropical
cyclone with maximum winds near 30 kt.

The initial motion is a somewhat uncertain 315/6 kt.  Later today,
the system should turn north-northwestward between the subtropical
ridge over the Atlantic and a deep-layer trough over the
southeastern United States.  The track models are in good
agreement during this part of the system's life, and this portion
of the new forecast track is almost the same as the previous track.
After 72 h, the guidance continues to be quite divergent. Most of
the deterministic and consensus models now show a turn toward the
east caused by Hurricane Humberto passing to the east of the system
and breaking down the ridge. However, the HMON and HAFS-A models
still show landfall in the southeastern United States, as do several
ECMWF and GFS ensemble members. Given the current guidance and the
trends, the new forecast track calls for a slow turn to the
northeast and east after 72 h, but at a much slower forward speed
than most of the guidance. It should be noted that while this
forecast keeps the system offshore, it would still be large enough
and close enough to cause wind and coastal flooding impacts along
the southeastern U.S. coast, as well as heavy rainfall/flooding
concerns in inland areas.

Based on current trends in the satellite imagery and the global
models, the disturbance will likely take another 12-18 h to become
a tropical cyclone. After that happens, strengthening is expected
through 72 h as the system moves through an upper-level wind
environment of moderate shear and strong divergence. The intensity
forecast continues to show the system reaching hurricane strength
in 3-4 days, which is in agreement with the intensity consensus.
Some weakening is expected by 120 h due to shear and possible
interaction with a frontal system approaching from the northwest.


KEY MESSAGES:

1. The disturbance is forecast to become a tropical storm this
weekend and bring tropical storm conditions to portions of the
central and northwestern Bahamas, where Tropical Storm Warnings are
in effect.

2. Rainfall associated with this system is expected to impact
eastern Cuba, Hispaniola, Jamaica, and the Bahamas through the
weekend, which will likely produce flash and urban flooding.  
Mudslides are possible in the higher terrain.

3.  There is an increasing threat of heavy rainfall early next
week from coastal Georgia through the Carolinas and into the
southern Mid-Atlantic states, which could cause flash, urban, and
river flooding.

4. The system is expected to be at or near hurricane intensity
when it approaches the southeast U.S. coast early next week, where
there is a risk of storm surge and wind impacts. Residents in that
area should monitor updates to the forecast and ensure they have
their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 21.9N  75.8W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
12H  27/1800Z 22.5N  76.4W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
24H  28/0600Z 23.8N  77.0W   35 KT  40 MPH...TROPICAL STORM
36H  28/1800Z 25.3N  77.5W   40 KT  45 MPH
48H  29/0600Z 27.0N  77.9W   50 KT  60 MPH
60H  29/1800Z 28.8N  78.5W   60 KT  70 MPH
72H  30/0600Z 30.2N  78.8W   65 KT  75 MPH
96H  01/0600Z 31.5N  78.7W   65 KT  75 MPH
120H  02/0600Z 31.5N  77.8W   55 KT  65 MPH

$$
Forecaster Beven

hei

接下來的藤原都考起了GOOGL了

pocketbox

WTNT44 KNHC 271450
TCDAT4

Tropical Depression Nine Discussion Number   4
NWS National Hurricane Center Miami FL       AL092025
1100 AM EDT Sat Sep 27 2025

Deep convection has increased over the disturbance this morning, and
dropsonde data from a NOAA Hurricane Hunter aircraft indicate
pressures are gradually falling between the central Bahamas and
eastern Cuba. In addition, dropsonde and flight-level wind data from
the aircraft show the low-level circulation has become better
defined. Based on these developments, the disturbance is now
classified as a 30-kt tropical depression for this advisory. An Air
Force Reserve Hurricane Hunter mission is scheduled to investigate
the disturbance later today.

The initial motion of the depression is an uncertain 320/5 kt. A
north-northwestward motion is expected as the system moves between a
deep-layer trough over the southeastern U.S. and a subtropical ridge
over the Atlantic. The track models are in good agreement through
72 h, and little change was made to this portion of the NHC track
forecast. This brings the center over the central and northwestern
Bahamas this weekend, moving roughly parallel to but offshore the
east coast of Florida. During this time, strengthening is forecast
as the system moves over warm waters within a diffluent upper-level
environment. However, the aforementioned trough should impart
moderate southerly shear over the cyclone, likely resulting in an
asymmetric storm structure. The near-term NHC intensity forecast was
raised slightly from the previous one and still shows a 65-kt
hurricane early next week off the southeastern U.S coast.

The track forecast beyond 72 h is still of low confidence, with a
bifurcation of solutions noted in the various deterministic models
and GFS, ECMWF, and Google DeepMind ensemble members. Much depends
on the future track of Hurricane Humberto, the extent to which it
erodes the steering ridge over the Atlantic, and the strength and
timing of an upper trough expected to dig over the northwestern
Atlantic next week. A majority of the deterministic guidance
suggests that the system will slow down or briefly stall offshore of
the southeast U.S. coast before turning sharply eastward. There
remains considerable uncertainty in how quickly this might occur,
and it must be noted that some ensemble solutions still show the
system reaching the coast. For now, the NHC forecast continues to
show an eastward turn at days 4-5, but at a much slower forward
speed than most of the models.

Given the risk of tropical-storm-force winds along the east coast of
Florida, a Tropical Storm Watch has been issued from the Palm
Beach/Martin County Line northward to the Flagler/Volusia County
Line. Although it is still too early to specify the details of
potential impacts along the remainder of the southeast U.S. coast,
there remains a risk of heavy rainfall, storm surge, and wind
impacts.


KEY MESSAGES:

1. The depression is expected to strengthen and bring tropical storm
conditions to portions of the central and northwestern Bahamas
through Sunday night. Tropical storm conditions are also possible
along portions of the east coast of central Florida beginning
Monday, where a Tropical Storm Watch has been issued.

2. Rainfall associated with this system will continue to impact
eastern Cuba, Hispaniola, Jamaica, and the Bahamas through the
weekend, which will likely produce flash and urban flooding.  
Mudslides are possible in the higher terrain.

3.  There is a significant threat of heavy rainfall early next week
from coastal Georgia through the Carolinas and into the southern
Mid-Atlantic states, which could cause flash, urban, and river
flooding.

4. The depression is expected to be at or near hurricane intensity
when it approaches the southeast U.S. coast early next week, where
there is a risk of storm surge and wind impacts.  Although it is too
soon to specify the exact location and magnitude of impacts,
residents should closely monitor the latest forecast updates and
ensure that they have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 22.0N  76.2W   30 KT  35 MPH
12H  28/0000Z 23.0N  76.7W   35 KT  40 MPH
24H  28/1200Z 24.4N  77.3W   40 KT  45 MPH
36H  29/0000Z 26.1N  77.7W   45 KT  50 MPH
48H  29/1200Z 27.9N  78.2W   55 KT  65 MPH
60H  30/0000Z 29.6N  78.6W   60 KT  70 MPH
72H  30/1200Z 30.7N  78.8W   65 KT  75 MPH
96H  01/1200Z 31.3N  77.5W   65 KT  75 MPH
120H  02/1200Z 31.5N  75.0W   60 KT  70 MPH

$$
Forecaster Reinhart

ygsj24

000
WTNT34 KNHC 271747
TCPAT4

BULLETIN
Tropical Depression Nine Intermediate Advisory Number 4A
NWS National Hurricane Center Miami FL       AL092025
200 PM EDT Sat Sep 27 2025

...HEAVY RAINS CONTINUE OVER PORTIONS OF EASTERN CUBA AND THE
BAHAMAS...
...AIR FORCE HURRICANE HUNTERS EN ROUTE TO INVESTIGATE THE SYSTEM...


SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...22.0N 76.5W
ABOUT 195 MI...310 KM NW OF THE EASTERN TIP OF CUBA
ABOUT 120 MI...190 KM SSW OF THE CENTRAL BAHAMAS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Central Bahamas, including Cat Island, the Exumas, Long Island,
Rum Cay, and San Salvador
* Portions of the northwestern Bahamas, including Eleuthera, New
Providence, the Abacos, Berry Islands, Andros island, and Grand
Bahama Island

A Tropical Storm Watch is in effect for...
* East coast of Florida from the Palm Beach/Martin County Line to
the Flagler/Volusia County Line

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

Interests elsewhere in the Bahamas and along the southeast coast of
the United States from Florida to North Carolina should monitor the
progress of this system. Additional watches could be required later
today or tonight.

For storm information specific to your area in the United States,
including possible inland watches and warnings, please monitor
products issued by your local National Weather Service forecast
office. For storm information specific to your area outside of the
United States, please monitor products issued by your national
meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 200 PM EDT (1800 UTC), the center of Tropical Depression Nine was
located near latitude 22.0 North, longitude 76.5 West. The
depression is moving toward the northwest near 6 mph (9 km/h).  A
north-northwestward motion is expected to begin tonight and continue
through Monday. On the forecast track, the center of the system is
expected to move across the central and northwestern Bahamas on
Sunday and Sunday night and approach the southeast U.S. coast early
next week.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Strengthening is expected during the next few days, and the system
is forecast to become a tropical storm tonight and a hurricane by
late Monday or Tuesday.

The estimated minimum central pressure is 1005 mb (29.68 inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Tropical Depression Nine can be found in the
Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO
header WTNT44 KNHC.

WIND: Tropical storm conditions are expected in the central Bahamas
beginning later today or early Sunday and in the northwestern
Bahamas on Sunday. Tropical storm conditions are possible in the
watch area along the east coast of Florida on Monday.

RAINFALL: Tropical Depression Nine is expected to produce rainfall
amounts of 8 to 12 inches with isolated maximum totals of 16 inches
possible in eastern Cuba, and 4 to 8 inches of rain in the Bahamas.
Across Hispaniola, Jamaica, and portions of central and southern
Cuba, an additional 2 to 4 inches of rain is expected. This rainfall
will likely produce flash and urban flooding. Mudslides are also
possible in areas of higher terrain across eastern Cuba, Hispaniola,
and Jamaica.

Moisture from Tropical Depression Nine will lead to a threat of
heavy rainfall well to the north from Coastal Georgia through the
Carolinas and into the southern Mid-Atlantic states into early next
week which could cause flash, urban, and river flooding.

For a complete depiction of forecast rainfall and flash flooding
associated with the system, please see the National Weather Service
Storm Total Rainfall Graphic, available at
hurricanes.gov/graphics_at4.shtml?rainqpf.

STORM SURGE: A storm surge will raise water levels by as much as 1
to 3 feet above ground level along the immediate coast in areas of
onshore winds in the northwestern Bahamas. Near the coast, the
surge will be accompanied by large waves.

SURF: Swells generated by this system and Hurricane Humberto will
affect portions of the Bahamas this weekend, and spread to portions
of the southeast U.S. coast early next week. These swells are likely
to cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.

A depiction of rip current risk for the United States can be found
at: hurricanes.gov/graphics_at4.shtml?ripCurrents


NEXT ADVISORY
-------------
Next complete advisory at 500 PM EDT.

$$
Forecaster Reinhart

ygsj24

000
WTNT44 KNHC 272044
TCDAT4

Tropical Depression Nine Discussion Number   5
NWS National Hurricane Center Miami FL       AL092025
500 PM EDT Sat Sep 27 2025

The organization of the depression has not changed much since this
morning. Some deep convection has flared up this afternoon near the
estimated center, which appears broad in the 850-mb flight-level
wind data from the Air Force Hurricane Hunters. The earlier
scatterometer winds and more recent aircraft data do not suggest the
system has intensified. The initial intensity is held at 30 kt for
this advisory.

The center appears to be slightly south and west of previous
estimates, with an uncertain initial motion of 315/4 kt. Over the
next couple of days, the system should turn more north-northwestward
within the flow between an upper trough over the southeast U.S. and
a subtropical ridge over the Atlantic. This forecast brings the
depression over the central and northwestern Bahamas through early
Monday, then toward the southeast U.S. coast by Tuesday. The NHC
track forecast is very similar to the previous one, with only a
slight nudge westward based on the initial position adjustments
during the day. Warm waters and strong upper-level divergence should
promote strengthening during the next few days, but this could be
tempered by moderate southerly shear over the system from an
upper-level trough. The NHC intensity forecast shows steady
strengthening through early next week, with the system becoming a
hurricane by 60 h. This prediction lies close to the latest IVCN and
HCCA aids.

There is still above-average uncertainty in the details of the
long-range forecast. In general, the models agree that the presence
of Hurricane Humberto to the east will result in a weakening of the
prevailing steering currents, causing the system to slow down and
meander near the southeast U.S. coast on Tuesday. While the chances
of a landfall appear lower than yesterday, there are still some
hurricane regional models and ensemble solutions that show this
possibility. Given the expected asymmetric storm structure, a risk
of significant heavy rainfall, storm surge, and wind impacts exists
for the southeast U.S. coast even if the storm center remains
offshore. The increased track spread at 96-120 h is related to
whether the system feels the effects of an amplifying upper-level
trough behind Humberto over the western Atlantic. While many global
models show a sharp eastward turn and acceleration away from land,
the system fails to be captured by the trough in the 12z ECMWF and
lingers offshore. The NHC track forecast at days 4-5 maintains a
consensus approach and shows a slower eastward motion, but future
track adjustments are likely as confidence increases. The system may
be in close proximity to fronts by the end of the period, so
extratropical transition could begin around or shortly after day 5.


KEY MESSAGES:

1. The depression is expected to strengthen and bring tropical storm
conditions to portions of the central and northwestern Bahamas
through Sunday night. Tropical storm conditions are also possible
along portions of the east coast of central Florida beginning
Monday, where a Tropical Storm Watch is in effect.

2. Rainfall will continue to impact eastern Cuba, Hispaniola,
Jamaica, and the Bahamas through the weekend, which will likely
produce flash and urban flooding. Mudslides are possible in the
higher terrain.

3. There is a significant threat of heavy rainfall early next week
from portions of the east coast of Florida northward into the
Carolinas, which could cause flash, urban, and river flooding.

4. The depression is expected to be at or near hurricane intensity
when it is closest to the southeast U.S. coast early next week,
where there is a risk of storm surge and wind impacts. Although it
is too soon to specify the exact location and magnitude of impacts,
residents should closely monitor the latest forecast updates and
ensure that they have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/2100Z 22.2N  76.5W   30 KT  35 MPH
12H  28/0600Z 23.3N  77.1W   35 KT  40 MPH
24H  28/1800Z 24.9N  77.6W   45 KT  50 MPH
36H  29/0600Z 26.7N  78.1W   55 KT  65 MPH
48H  29/1800Z 28.5N  78.6W   60 KT  70 MPH
60H  30/0600Z 30.0N  78.8W   65 KT  75 MPH
72H  30/1800Z 30.8N  78.6W   65 KT  75 MPH
96H  01/1800Z 31.1N  76.8W   65 KT  75 MPH
120H  02/1800Z 31.5N  74.0W   60 KT  70 MPH

$$
Forecaster Reinhart

pocketbox

WTNT44 KNHC 280256
TCDAT4

Tropical Depression Nine Discussion Number   6
NWS National Hurricane Center Miami FL       AL092025
1100 PM EDT Sat Sep 27 2025

The depression this evening remains fairly disorganized, with
convection mainly oriented in a north-south fashion with only a
hint of banding on the northern side. A NOAA-P3 aircraft that
has been flying through the system only found a peak 700 mb flight
level wind of 34 kt about 60 n mi away from the center. Tail Doppler
Radar (TDR) analysis from the aircraft also shows the center is
quite broad at the 1 km level with the mid-level center tilted to
the south with height. Based on the plane data, the initial
intensity remains 30 kt this advisory, which is a little under the
various satellite-based estimates, but close to a recently
received scatterometer pass which had a peak wind of 31 kt.

Aircraft fixes both at 700 mb and from the TDR analysis shows the
cyclone is meandering right now, with a best guess at a motion of
310/2 kt. Over the next couple of days, the system should turn
north-northwestward with a somewhat faster forward motion, moving
within the flow between an upper trough over the southeast U.S. and
a subtropical ridge over the Atlantic. This forecast brings the
depression over the central and northwestern Bahamas through early
Monday, then toward the southeast U.S. coast by Tuesday. It is
notable to point out the system has been moving slower than
anticipated over the last 12-24 hours, and this could have
significant implications on its ultimate track. Even in the first
48 hours of the track, there is quite a bit of spread in the
north-south direction in both the deterministic and ensemble model
guidance. Faster tracks appear to interact more with the upper-level
trough to the west, resulting in a track closer to the Carolina
coastline, while slower tracks largely miss a direct interaction
with this feature, and turn sharply east faster as Hurricane
Humberto approaches from the east, eroding the mid-level ridging
steering TD9 northward. Because it has been moving slower than
expected, its becoming more likely its ultimate track will fall in
the slower and sharper east camp. In response, the overall track
guidance this cycle shifted slower and further east, and the NHC
track forecast was shifted in that direction. The latest track
roughly splits the difference between the ECMWF and GFS tracks, and
lies quite close to the HCCA consensus aid, but still not as far
south and east as the Google DeepMind ensemble mean (GDMI).

The depression is now showing signs of intensification yet, with a
broad diffuse structure on aircraft observations persisting.
However, the intensity guidance is insistent that deep central
convection will soon form near the center, helping to tighten up the
surface wind field. While the cyclone will have some southerly shear
to deal with, it does not appear to be prohibitively strong, only
15-20 kt for the next 48 hours in both the GFS and ECMWF-based SHIPS
guidance. That, combined with warm 29-30 C sea-surface temperatures
should promote steady intensification once a central core develops,
and the NHC intensity forecast was nudged up a little higher showing
a 70 kt peak in 48 hours. After this period is where the intensity
forecast gets tricky. The large spread in north-south tracks also
has a significant impact on the amount of shear the system will face
in the 48-96 hour time-frame. Solutions that are further south have
less shear to contend with and are generally stronger. For now, the
latest intensity forecast will cap the peak intensity at 70 kt
through the end of the forecast, close to the HCCA intensity
guidance, but this could be conservative if the track shifts further
south and east. The system could also interact with a baroclinic
zone towards the end of the forecast, but because the forecast track
remains over warm waters at day 5, extratropical transition won't be
shown quite yet.

Even if this further offshore track pans out, the wind field is
expected to expand quite a bit, and given the expected storm
structure, a risk of significant heavy rainfall, storm surge, and
wind impacts is still possible for the southeast U.S. coast even if
the storm center remains offshore.

KEY MESSAGES:

1. The depression is expected to strengthen and bring tropical storm
conditions to portions of the central and northwestern Bahamas
through Sunday night. Tropical storm conditions are also possible
along portions of the east coast of central Florida beginning
Monday, where a Tropical Storm Watch is in effect.

2. Rainfall will continue to impact eastern Cuba and the Bahamas
through the weekend, which will likely produce flash and urban
flooding. Mudslides are possible in the higher terrain.

3. There is a significant threat of heavy rainfall early next week
from portions of the east coast of Florida northward into the
Carolinas, which could cause flash, urban, and river flooding.

4. The depression is expected to be at or near hurricane intensity
when it is closest to the southeast U.S. coast early next week,
where there is a risk of storm surge and wind impacts. Although it
is too soon to specify the exact location and magnitude of impacts,
residents should closely monitor the latest forecast updates and
ensure that they have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 22.4N  76.7W   30 KT  35 MPH
12H  28/1200Z 23.6N  77.0W   35 KT  40 MPH
24H  29/0000Z 25.5N  77.5W   50 KT  60 MPH
36H  29/1200Z 27.3N  77.9W   60 KT  70 MPH
48H  30/0000Z 28.7N  78.2W   70 KT  80 MPH
60H  30/1200Z 29.9N  78.1W   70 KT  80 MPH
72H  01/0000Z 30.4N  77.3W   70 KT  80 MPH
96H  02/0000Z 31.0N  75.0W   70 KT  80 MPH
120H  03/0000Z 31.5N  71.4W   70 KT  80 MPH

$$
Forecaster Papin

ygsj24

000
WTNT44 KNHC 280856
TCDAT4

Tropical Depression Nine Discussion Number   7
NWS National Hurricane Center Miami FL       AL092025
500 AM EDT Sun Sep 28 2025

The depression has been slowly becoming more organized overnight.  
The minimum central pressure has fallen to 1003 mb, and satellite
images are indicating that a tighter circulation has formed along
with increasing deep convection.  The initial intensity is held at
30 kt per the latest aircraft flight-level winds, but this system
will probably become a tropical storm soon.

The initial motion is a bit faster to the north-northwest, or 345/6
kt.  This general motion with a turn towards the north is
anticipated during the next couple of days while the system moves
between an upper trough over the southeastern United States and the
subtropical ridge.  Beyond that time, models are generally faster
and more offshore of the United States with the eventual track of
the tropical cyclone, following the trend of the past few cycles,
due to it missing the upper trough and eventually following
Hurricane Humberto more out to sea.  While it is too early to feel
extremely confident, almost all of the reliable ensembles now keep
the system offshore of the southeastern United States, though some
impacts are still anticipated.  The latest NHC forecast is shifted
to the south and east, but is not nearly as far to the southeast as
the latest consensus models due to continuity constraints.  

Now that a better-defined core has formed, gradual intensification
is anticipated for the next couple of days while the system remains
in a warm water but moderate shear environment.  The intensity
forecast is similar to the previous one through the first couple
days of the forecast.  Afterwards, the intensity forecast is
slightly raised as the system could find itself in a lower shear
environment while still over warm waters.  By the end of the
forecast, interaction with a frontal boundary is likely to cause
some weakening, along with extratropical transition.  This is a low
confidence forecast at long range given the recent large track
changes.


KEY MESSAGES:

1. The depression is expected to strengthen and bring tropical storm
conditions to portions of the central and northwestern Bahamas
through tonight. Tropical storm conditions are also possible
along portions of the east coast of central Florida beginning
Monday, where a Tropical Storm Watch is in effect.

2. Rainfall associated with Tropical Depression Nine will continue
to impact eastern Cuba and the Bahamas through Tuesday, which will
likely produce flash and urban flooding.  Mudslides are possible in
the higher terrain.  Heavy rainfall across the coastal Carolinas
could cause flash, urban, and river flooding into Wednesday
morning.

3. There is still a risk of heavy rainfall, wind and high surf
impacts for the southeast U.S. coast even if the center
remains offshore.  Residents should closely monitor the latest
forecast updates and ensure that they have their hurricane plan in
place.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 23.0N  77.2W   30 KT  35 MPH
12H  28/1800Z 24.1N  77.4W   40 KT  45 MPH
24H  29/0600Z 25.7N  77.6W   50 KT  60 MPH
36H  29/1800Z 27.4N  77.8W   60 KT  70 MPH
48H  30/0600Z 28.8N  77.8W   65 KT  75 MPH
60H  30/1800Z 29.5N  77.4W   70 KT  80 MPH
72H  01/0600Z 29.9N  75.5W   70 KT  80 MPH
96H  02/0600Z 30.6N  72.1W   75 KT  85 MPH
120H  03/0600Z 31.7N  66.4W   65 KT  75 MPH...POST-TROP/EXTRATROP

$$
Forecaster Blake