[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120502
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Oct 12 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
0450 UTC.

...SPECIAL FEATURES...

Tropical Depression Sean is near 12.0N 36.2W, or about 750 nm WSW
of the Cabo Verde Islands, moving WNW at 11 kt. Maximum sustained
winds are 30 kt with gusts to 40 kt. Minimum central pressure is
1007 mb. Scattered moderate isolated strong convection extends
outward up to 240 nm in the NE semicircle. Scattered moderate
convection is also noted west of Sean from 11N to 14N between 38W
and 42.5W. Peak seas are 11 ft. A west-northwestward or
northwestward track at a slightly slower forward speed is expected
during the next few days. Little change in strength is forecast
during the next few days.

Northern Gulf of Mexico and Western Atlantic Ocean Gale Warning:
Low pressure of 998 mb is centered over the north-central Gulf of
Mexico near 29N88W, as of 0300 UTC. A cold front extends from the
low southwestward to 26.5N91W, and a surface trough continues from
26.5N91W to 21N94.5W. A warm front extends from the low eastward
to Crystal River, Florida near 29N82.5W. Near-gale to gale force
winds are occurring from offshore SE Louisiana eastward to
offshore of the western Florida Panhandle. In addition, numerous
moderate to scattered strong convection is occurring over the NE
Gulf of Mexico, north of 26.5N and east of 88W. Observations from
many buoys over the northern Gulf, north of 28N between 86W and
92W, imply sustained winds up to 40 kt with gusts to 50 kt at a
height of 10 meters have been occurring during the evening and
overnight. Buoy 42012 near 30.1N 87.5W recently reported a
significant wave height of 12.5 ft along with winds of 39 kt
gusting to 47 kt. However, seas are peaking now as high as 14 ft
over portions of the north-central Gulf, indicated by recent
altimeter satellite data. The low pressure system is expected to
move inland over northern Florida by early this morning, and the
gale force winds in the Gulf will diminish during the early
morning.

The low pressure along the frontal system will move into the
western Atlantic today, and gale force winds should develop north
of 30N and east of 80W by mid to late morning today. The gales
will shift east of 75W by this evening, and across the northeast
waters Fri through early Sat. Gale-force winds are forecast to
affect the northern offshore waters north of 30N through tonight
and north of 27N Fri through Fri evening. Heavy showers and rough
seas are expected with this frontal system. As the system moves E,
gale force winds may occur as far south of 27N between 55W and
65W on Fri. Seas will build to 12 to 16 ft Fri east of 65W and
north of 26N.

Please read the latest High Seas Forecast issued by the National
Hurricane Center at the website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for details on Sean
and the gales in the Gulf of Mexico and Atlantic.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 21W from 03N
to 17N, moving westward 10 kt. A broad 1010 mb low (Invest AL94)
is located on the wave near 10N. Scattered moderate isolated
strong convection is within 150 nm NE of the low from 10N to 12N
between 19W and 21W. This activity remains disorganized.
Environmental conditions appear conducive for some slow
development over the next few days. This system should move
westward across the eastern and central tropical Atlantic through
early next week. The system has a low chance of tropical cyclone
formation within the next 48 hours.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coast of Senegal near
14N17W to Invest AL94 near 10N21W to 10N30W. The monsoon trough
resumes from 10N39.5W to 08N44W. the ITCZ continues from 08N44W to
08N50W to 10N56W. Aside from the convection mentioned in the
sections above associated with Sean and AL94, scattered moderate
convection is noted from 03N to 10N between 11W and 14W, and from
03N to 08N between 29W and 32W.

GULF OF MEXICO...

Please read the Special Features section for details about the
ongoing gale event over the north-central and northeastern Gulf of
Mexico.

Outside of the gale area, strong S to SW winds prevail over the
eastern Gulf, to the east of the cold front, north of 26N, along
with seas of 7 to 11 ft. Fresh to locally strong S winds are over
the SE Gulf, south of 26N to the Yucatan Channel and Straits of
Florida, with seas around 6 ft. To the west of the cold front,
south of the Louisiana coast, winds are still strong to near gale
force and seas are still rough, based on recent data. Gentle to
moderate winds and 2 to 4 ft seas are found over the southwestern
Gulf of Mexico. Isolated thunderstorms are over the south-central
Gulf of Mexico.

For the forecast, NE gales are expected N of the low and front
through the next few hours, as this system moves E-NE and inland
across N Florida this morning. Scattered to numerous strong
thunderstorms and strong winds will accompany this frontal
boundary across the northern Gulf through early this morning.
High pressure across the Atlantic will build modestly westward
into the eastern Gulf Fri through early Sat, before the next cold
front moves into the NW Gulf Sat morning and across the entire
basin by Sun evening.

CARIBBEAN SEA...

Mid- to upper-level anti-cyclonic flow prevails across most of the
basin, which is leading to subsidence and relatively dry
conditions. The exception is the far SW Caribbean, where scattered
showers and isolated thunderstorms are found south of 13N.

Fresh trades prevail across the central Caribbean between 67W and
76W, locally strong near the coasts of NW Venezuela and NE
Colombia, including the Gulf of Venezuela, as indicated by a
recent ASCAT satellite data pass. The ASCAT pass also shows strong
SE winds in the Gulf of Honduras. A large area of fresh to strong
SE winds likely currently covers the NW Caribbean. Seas are 5-7 ft
across the central Caribbean and 5-8 ft in the NW Caribbean.
Moderate winds with 4-5 ft seas are in the far eastern Caribbean.

For the forecast, moderate to fresh trade winds across the
eastern and central Caribbean will diminish to gentle to moderate
Fri morning and prevail through Mon night. Fresh to strong SE to S
winds in the Gulf of Honduras and NW Caribbean will continue
through Fri night. A cold front will sink S-SE across the western
Atlantic over the weekend and act to weaken the trade wind flow
across the basin.

ATLANTIC OCEAN...

Please read the Special Features section for details about
Tropical Depression Sean and on an upcoming western Atlantic gale
event. Please read the Tropical Waves section for details about
Invest-AL94 and the associated tropical wave.

A cold front extends from near 31N48W to 28N56W to 29N67W, where
it transitions to a warm front to 29.5N72W to Cape Canaveral,
Florida. Scattered moderate convection is moving off the coast of
northern Florida, with isolated showers elsewhere near the warm
front. Fresh to strong winds are also now starting to move off
northern Florida where seas near 6 ft will build quickly later
this morning as winds increase due to a low pressure system
mentioned above in the Special Features section. High pressure of
1015 mb is located at 24N62W. Gentle winds prevail across much of
the Atlantic north of 22N between 58W and 75W with 4 to 5 ft seas,
except moderate winds near the aforementioned fronts. Fresh trades
are north of Hispaniola.

Farther east, a warm front extends from 31N45W to 29N44W. Upper-
level diffluence is supporting scattered moderate to strong
convection from 24N to 31N between 38W and 48W. Similar convection
is seen within 60 nm either side of a line extending from 31N25W
to 26.5N38W. Fresh SW winds and rough seas are occurring near
this line of convection. Moderate to fresh winds and 6 to 7 ft
seas are likely occurring from 26N to 31N between 44W and 56W. A
1016 mb high pressure is centered near 23.5N32W.

For the forecast W of 55W, 998 mb low pressure along the front in
the Gulf of Mexico is expected to move eastward across N Florida
early this morning, then continue eastward and emerge across the
W Atlc, bringing strong to near gale force winds east of northern
and central Florida today, then move E of 75W Thu night, and
across the NE waters Fri through early Sat. Gale force winds are
forecast to affect the northern offshore waters N of 30N through
tonight and N of 27N Fri through Fri evening. Scattered showers
and thunderstorms and high seas are expected with this frontal
system.

$$
Hagen
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