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Atlantic Tropical Weather Discussion

AXNT20 KNHC 252305

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 26 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 1800 UTC surface analysis and satellite imagery through 
2200 UTC.


Tropical Storm Philippe is centered near 17.3N 46.7W at 2100 UTC, 
or 1080 nm E of the Northern Leeward Islands, moving W at 13 kt. 
Maximum sustained winds are 40 kt gusting to 50 kt. Estimated 
minimum central pressure is 1002 mb. Peak seas are near 20 ft.
Westerly upper level wind shear continues to displace the
associate deep convection to the east of the center this 
afternoon. Scattered to numerous moderate to strong convection is 
seen from 90 to 420 nm east of the center between 15N and 20N. A 
turn to the west-northwest is expected by tonight, and a 
northwestward motion is forecast to occur in a couple of days. 
Little change in strength is forecast during the next few days as 
Philippe remains in a sheared environment. 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.

Eastern Tropical Atlantic (AL91): A tropical wave located 
several hundred miles west-southwest of the Cabo Verde Islands,
along 32-33W, and continues to produce disorganized showers and 
thunderstorms. Maximum sustained winds are estimated at 20 kt and
peak seas to 9 ft. Scattered to numerous moderate to strong 
convection is noted from 06N-14N between 28W-38W. Environmental 
conditions are forecast to be conducive for gradual development, 
and a tropical depression is likely to form within the next few 
days as the system moves west-northwestward across the central 
tropical Atlantic. There is a medium chance of formation through 
48 hours.


An east Atlantic tropical wave - Invest AL91 - has its axis 
along 32-33W between 03N-17N, moving westward at 10-15 kt. See 
SPECIAL FEATURES above for more information.

A central Caribbean tropical wave has its axis along 79W, south 
of 19N, moving westward at 10-15 kt. Numerous moderate and 
scattered strong convection is noted from 10N-19N between 77W- 


The monsoon trough leaves the coast of Senegal near Dakar and 
continues to 09.5N24W to 1010 mb low pressure (AL91) near
10.5N32.5W and then to 06.5N42W. The monsoon trough begins again 
at 15N48W to 10N53W, where the ITCZ then extends W-SW to the 
coast of Venezuela near 09N61.5W. Scattered moderate and isolated
strong convection is noted from 04N-11.5N between 14W-21W and 
from 08.5N-12.5N between 46W-61W. Scattered moderate convection 
is noted from 10N-14N east of 20W.


A surface trough extends from the Yucatan peninsula near 21N89W 
north-northeastward to 28.5N85W. Widely scattered moderate 
convection is noted across the waters of the Florida Big Bend, and
south of south of 24.5N between 83W and 89W. The surface trough 
and convection are being forced by a deep-layered upper trough 
over the same location. Moderate winds surround the northern
periphery of the trough, where seas are 3-4 ft. Winds removed 
from any thunderstorms are light to gentle with seas 2-3 ft.

For the forecast, the surface trough over the southeast and 
south-central Gulf accompanied by scattered showers and 
thunderstorms will drift slowly westward, and 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. Winds may 
increase over the northern Gulf the end of the week into the 


The Bermuda-Azores High located well north of the Caribbean is
interacting with the 1008 mb Colombian Low to produce generally 
fresh trades over the central Caribbean, and southwest of Jamaica,
while gentle to moderate prevail elsewhere. Seas are 5-8 ft over 
the central Caribbean and SW of Jamaica, and 3-4 ft elsewhere. 
Numerous moderate and scattered strong convection is noted from 
10N-19N between 77W-82W in association with the tropical wave,
while scattered moderate isolated strong convection extends from
the NE coast of Honduras northward to the W coast of Cuba. Winds 
and seas are higher in association with this thunderstorm 

In 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 Atlantic. Scattered deep convection 
associated with the interaction of the tropical wave and deep 
layered low pressure across the southeast Gulf of Mexico and the
Yucatan Peninsula will shift westward through Wed.


Refer to the SPECIAL FEATURES section for details on Tropical 
Storm Philippe and Invest AL91.

An expansive Bermuda-Azores High and associated ridge extends 
just north of our waters, to the east of 64W. Aside from higher 
winds near Philippe and Invest AL91, the trades are generally 
gentle to moderate, with seas 6-8 ft in the central and eastern 
Atlantic and light to gentle, with seas 4-6 ft in the western 
Atlantic. A surface trough extends from 25N65W to 28N63W with 
scattered moderate convection within 120 NM east of the trough 
axis, but no enhancement of winds or seas. Moderate to fresh
trades prevail E of 35W to offshore of Africa, with seas generally
6 to 7 ft.

Philippe will move to 17.7N 48.5W Tue morning, to near 18.4N 
50.4W Tue afternoon, to near 19.3N 52.3W Wed morning, to near 20.4N
54.0W Wed afternoon, to near 21.6N 55.4W Thu morning, and near 22.2N
56.3W Thu afternoon. Philippe will change little in intensity as 
it moves to near 22.9N 57.7W Fri afternoon. 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 will build by Thu north of the Bahamas and east 
of Florida in NE swell mixing with ESE from from Philippe.