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Atlantic Tropical Weather Discussion

AXNT20 KNHC 251024

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Sep 25 2023

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through 
1010 UTC.


Tropical Storm Philippe is centered near 17.4N 43.9W at 25/0900
UTC or 1150 nm W of the Cabo Verde Islands, moving WNW at 9 kt.
Estimated minimum central pressure is 1000 mb. Maximum sustained
wind speed is 45 kt with gusts to 55 kt. Peak seas near the 
center are up to 20 ft. Numerous moderate scattered strong 
convection is noted within 210 nm in the southeast semicircle of
the low and within 90 nm in the northwest semicircle. A continued
west- northwest motion is expected for the next day or two, with 
a gradual turn to the northwest anticipated by mid- week. Little 
overall change in strength is forecast during the next 2 to 3 

Please, read the latest HIGH SEAS FORECAST, that is
issued by the National Hurricane Center, at the website-, and the
latest Tropical Storm Philippe NHC Forecast/Advisory
and Public Advisory, at, for more details.


An eastern Atlantic tropical wave (Invest 91L) has its axis along
29W, south of 19N, moving westward at 10 kt. A 1010 mb low 
pressure is along the wave axis near 09N29W where it intersects
the monsoon trough. Scattered moderate to isolated strong 
convection is observed within 120 nm of the low pressure. 
Environmental conditions are forecast to be conducive for 
additional development, and a tropical depression is likely to 
form around mid-week as the system moves west- northwestward 
across the central tropical Atlantic. The disturbance has a low 
chance of development over the next 48 hours. For more 
information, please read the Tropical Weather Outlook at

A central Caribbean tropical wave has its axis along 74W, south 
of 21N, moving westward at 10-15 kt. No deep convection is noted
near the trough axis.


The monsoon trough reaches the Atlantic through the coast of
Mauritania near 17N16W and continues southwestward to a 1010 mb 
low pressure (AL91) near 09N29W and then to 06N35W. The ITCZ 
extends from 06N35W to 08N42W, and from 12N48W to 09N58W. 
Scattered moderate convection is present within 120 nm on both 
sides of the ITCZ between 48W and 55W.


A broad surface trough extends from west-central Florida to the 
central Yucatan peninsula. Abundant tropical moisture and 
divergence aloft is enhancing the development of scattered showers
and thunderstorms across the SE Gulf, especially over and just
north of the Yucatan Channel. Fairly tranquil weather conditions 
are found elsewhere in the basin. The weak pressure gradient 
across the Gulf supports gentle to moderate winds and slight seas.

For the forecast, the surface trough over the southeast and 
south- central Gulf accompanied by scattered showers and 
thunderstorms will drift slowly into the western Gulf through mid 
week and dissipate. Meanwhile, weak high pressure will persist 
over the north-central and northeast Gulf. This pattern will 
support gentle to moderate NE to E winds and slight seas across 
the basin through the middle of the week. 


Abundant tropical moisture and a favorable upper level pattern
continue to sustain scattered moderate to isolated strong
convection north of 15N between 75W and 85W. Scattered showers 
are also noted in the eastern Atlantic, affecting the Windward
Islands. Isolated showers dot the remainder of the Caribbean Sea.

A building subtropical ridge over the central Atlantic and lower
pressures in northern South America support fresh to strong
easterly trade winds in the central Caribbean. An earlier scatterometer
satellite pass captured the strongest winds occurring off 
northern Colombia. Seas in these waters are 5-8 ft. Moderate to 
fresh easterly breezes are found in the eastern Caribbean Sea, 
along with seas of 3-6 ft. Elsewhere, light to gentle winds and 
slight seas prevail.

For the forecast, high pressure north of the area will continue to support
moderate to fresh trade winds across most of the eastern and 
central Caribbean into mid week, with fresh to strong pulses off 
northwest Venezuela and northeast Colombia during mainly the 
overnight and early morning hours. Seas will build in mixed NE and
E swell across the waters east of the Leeward Islands starting 
late Tue, ahead of Tropical Storm Philippe. Philippe is expected 
to turn NW before reaching 55W, and move into the central 


Refer to the Special Features section for details on Tropical 
Storm Philippe.

Upper level divergence is supporting scattered showers and a few
thunderstorms from central Cuba across the eastern Straits of
Florida to the northern Bahamas. Farther east, a surface trough 
between Bermuda and Hispaniola and divergence aloft continue to 
produce isolated to scattered moderate convection, especially 
north of 25N and between 60W and 65W. 

A surface trough reaches from 30N31W to 27N50W, south of a broad
ridge centered on 1023 mb high pressure near 35N45W. Fresh to
strong E winds and locally rough seas to 8 ft are noted near the
1010 mb low pressure at 09N29W. Elsewhere, outside of the area
impacted by Philippe, the pattern is supporting generally moderate
trade winds across the basin. Various altimeter pass over the past
several hours confirm mostly 5 to 7 ft combined seas across the

For the forecast west of 55W, Tropical Storm Philippe is well east of the area near
17.4N 43.9W at 5 AM EDT, and is moving west-northwest at 9 kt. 
Maximum sustained winds are 45 kt with gusts to 55 kt, and the 
minimum central pressure is 1000 mb. Philippe will continue to 
move west- northwest for the next day or two, with a gradual turn 
to the northwest anticipated by mid- week. Looking ahead, this 
path will place the center of the storm near 21.2N 53.3W Wed
afternoon, 22.4N 54.5W Thu morning and 24.0N 56.0W Fri. Regardless
of the exact position of the center later in the week, rough seas
ahead of the storm can be expected east of 60W starting late Tue.
Elsewhere, seas may build by Thu north of the Bahamas and east of
Florida in NE swell.