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Atlantic Tropical Weather Discussion

AXNT20 KNHC 230553

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Sat Sep 23 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 0000 UTC surface analysis and satellite imagery through 
0535 UTC.


Tropical Storm Ophelia is centered near 33.8N 77.1W at 23/0300 
UTC or 40 nm E of Cape Fear North Carolina, moving NNW at 10 kt. 
Estimated minimum central pressure is 984 mb. Maximum sustained 
wind speed is 60 kt with gusts to 75 kt. Scattered moderate and 
isolated strong convection is noted within 150 nm in the W 
quadrant of Ophelia. Peak seas are currently around 28 ft. On the 
forecast track, a turn toward the north is forecast today, 
followed by a turn toward the northeast on Sunday. Little change 
in strength is forecast before landfall along the coast of North 
Carolina. Weakening is expected after landfall through the rest of
the weekend, and Ophelia is likely to become extratropical by 
Saturday night. Swells generated by Ophelia will affect much of 
the east coast of the United States through this weekend. These 
swells are likely to cause life-threatening surf and rip current 
conditions. Please consult products from your local weather 
office. Please read the latest HIGH SEAS FORECAST issued by the 
National Hurricane Center at website 
- and the latest 
Ophelia NHC Forecast/Advisory and Public Advisory at for more details.

Invest 90L in the Central Tropical Atlantic: The axis of a 
tropical wave is analyzed along 35W with a 1008 mb low centered 
at 16N35W, or several hundred nautical miles west of the Cabo 
Verde Islands. Maximum winds are currently 25 kt and peak seas are
up to 11 ft. Numerous moderate to isolated strong convection is
noted from 13N to 18N and between 31W and 42W. A tropical
depression is likely to form during the next couple of days while
the system moves generally westward at 10 to 15 mph. The system 
is then expected to turn west-northwestward early next week as it 
moves over the central tropical Atlantic. The formation chance 
through 48 hours is high. Please see the latest Tropical Weather 
Outlook at for more information.


Please see the Special Features Section for details on the 
tropical wave (Invest 90L) along 35W.

A tropical wave has its axis along 60W near the Lesser Antilles, 
south of 22N, moving westward around 10 kt. A few showers are 
noted near the wave axis.


The monsoon trough enters the Atlantic through the coast of 
Guinea-Bissau near 12N17W and continues westward to the 
aforementioned low pressure (Invest 90L) near 16N35W, before 
terminating near 08N49W. No ITCZ is evident in the tropical 
Atlantic at this time. Scattered moderate to isolated strong
convection is noted over the coast of Africa, spilling into the
nearshore waters, mainly from 04N to 14N and east of 19W.


Scattered showers and isolated thunderstorms continue to affect
the SE Gulf waters and the Florida Straits in association with a
surface trough that extends from 27N89W to central Cuba. The rest
of the Gulf of Mexico is under the influence of a weak high
pressure system positioned off the southern coast of Louisiana,
sustaining moderate or weaker winds and seas of 1-3 ft. Stronger
winds, especially in gusts, are likely occurring near the stronger

For the forecast, weak high pressure over the lower Mississippi 
Valley and the northern Gulf will control the weather pattern 
across basin through the middle of next week, supporting mostly 
gentle to moderate winds and slight seas. 


A surface trough across western Cuba and converging low-level flow
due to Tropical Storm Ophelia well to the north support scattered
showers and a few thunderstorms over the NW Caribbean Sea and the
Windward Passage. A few showers are also noted off Panama and
northern Colombia. 

A weak pressure gradient across the Caribbean result in moderate
to fresh easterly trade winds in the central and eastern portions
of the basin, with the strongest winds occurring off NW Colombia.
Seas in these waters are 3-6 ft. Light to gentle winds and 1-3 ft
seas prevail elsewhere.

For the forecast, moderate to fresh trade winds in the central
Caribbean will change little through Sat. Winds across central
portions will increase modestly Sun through Mon as high pressure
strengthens across the region. Fresh to strong trade winds will
pulse offshore of northern Colombia and northwest Venezuela
during mainly the overnight and early morning hours into early
next week. Looking ahead, seas will build in mixed NE and E
swell across waters east of the Leeward Islands starting early
Mon, ahead of low pressure moving westward across the tropical
Atlantic, possibly as the next tropical cyclone. 


Please see the Special Features section section above for 
information on Tropical Storm Ophelia and Invest 90L.

Divergence aloft and low-level convergence associated with
Tropical Storm Ophelia well north of the area sustain scattered
moderate to isolated strong convection west of 67W, affecting the
Bahamas, Cuba and Hispaniola. Moderate to locally fresh westerly winds
and seas of 8-14 ft are found north of 28N and west of 73W.
Elsewhere west of 60W, moderate or weaker and moderate seas are

Farther east, an upper level low located well to the northeast of
the Leeward Islands is producing a few showers and isolated
thunderstorms, mainly from 21N to 28N and between 49W and 58W.
Moderate to locally fresh easterly winds and seas of 6-8 ft are
found in the area described. In the far eastern Atlantic, an
scatterometer satellite pass from a few hours ago captured fresh 
to locally strong NE winds from 18N to 24N and east of 24W. Seas 
in these waters are 6-8 ft. Elsewhere in the tropical Atlantic, a 
broad subtropical ridge sustains moderate or weaker winds and 
moderate seas.

For the forecast west of 55W, Tropical Storm Ophelia remains well
north of the area off the coast of North Carolina, and will 
continue to move northward and farther away from the forecast 
region. Large northerly swell on the southern periphery of Ophelia
will continue to impact the waters off northeast Florida 
overnight. A weak ridge will build in the wake of Ophelia off 
Florida through early next week, although a trough will persist 
across the Bahamas through Mon. Looking ahead, seas will build in 
mixed NE and E swell across waters northeast of the Leeward 
Islands starting Mon, ahead of low pressure moving westward across
the tropical Atlantic, possibly as the next tropical cyclone.