[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202240
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Thu Sep 21 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
2130 UTC.

...SPECIAL FEATURES...

Hurricane Nigel is centered near 37.4N 53.0W at 20/2100 UTC or
660 nm ENE of Bermuda, moving NNE at 16 kt. Estimated minimum
central pressure is 973 mb. Maximum sustained wind speed is 80
kt with gusts to 100 kt. Peak seas N of our area are currently
around 36 ft. Numerous moderate to strong convection is evident
within 270 nm in the S semicircle and 180 nm in the N semicircle
of Nigel. Hurricane Nigel should continue moving NNE tonight.
Gradual weakening is forecast as Nigel moves over increasing
cooler waters and into a more unfavorable environment. Nigel is
likely to weaken to a tropical storm Thu night, and become a
post- tropical cyclone Fri. Swells generated by Nigel will
affect Bermuda during the next couple of days. 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 -
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Nigel
NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov
for more details.

Atlantic Gale Warning: The pressure gradient between low
pressure that is expected to develop along a stationary front
N of the Bahamas and high pressure over the southeastern U.S.
will result in frequent wind gusts to gale force N of 30N and W
of 76W starting Thu afternoon, then N of 29N and W of 76W by late
Thu night. Seas with these winds are forecast to be 8 to 11 ft
and could be locally higher. Please see the latest NWS High Seas
Forecast issued by the National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2 for further details.

...TROPICAL WAVES...

A tropical wave is in the far eastern Atlantic Ocean along 22W,
moving W through the Cabo Verde Islands at around 10 kt. Scattered
moderate to strong convection is evident from 09N to 14N between
18W and 22W.

A tropical wave in the central Atlantic is centered along 36W,
from 19N southward, moving W at 5 kt. Scattered moderate to
isolated strong convection is evident from 09N to 15N between 34W
and 39W, and from 02N to 09N between 30W and 41W.

A western Atlantic tropical wave is along 50W, from 16N southward,
drifting W at less than 5 kt. No significant convection is
evident near this tropical wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends off the coast of Senegal near
15N17W to 10N33W to 09N47W. The ITCZ axis extends from 09N51W to
the Venezuela-Guyana border around 09N61W. Nearby significant
convection is discussed in the Tropical Waves section above.

...GULF OF MEXICO...

A slowly dissipating stationary front extends from near Sarasota,
Florida, to 26N86W. Scattered moderate convection is noted N of
this boundary. Moderate to fresh E winds are present N of the
front, with mainly gentle winds elsewhere. A 1011 mb low pressure
is centered offshore Texas near 27N95W. Convection previously
associated with this low has diminished this afternoon. A weak
surface trough is noted in the western Bay of Campeche, with
locally fresh NE winds behind it, W of the Yucatan Peninsula. A
weak surface trough is noted in the Bay of Campeche. Seas are 1-3
ft across the basin, locally 4 ft N of the stationary front
offshore the Florida Panhandle.

For the forecast, high pressure will be in control of the weather
pattern across the Gulf waters allowing for generally gentle to
moderate east to southeast winds and slight seas, except pulsing
to moderate to fresh offshore the western Yucatan Peninsula in
the evenings. Developing low pressure east of Florida will
tighten the pressure gradient over the NE Gulf bringing moderate
to locally fresh NE winds across the NE Gulf Thu night into Fri.
A frontal trough associated with the aforementioned low pressure
will move across the SE Gulf and the Straits of Florida Thu night
into Fri.

...CARIBBEAN SEA...

A deep layer trough E of the Yucatan Peninsula combined is
inducing scattered moderate convection in the NW Caribbean Sea. A
weak pressure gradient sustains mainly moderate to fresh easterly
trade winds in the central Caribbean. However, strong winds are
occurring just off the N Colombia and NW Venezuelan coasts. Seas
in the central Caribbean are in the range of 4-7 ft. Elsewhere,
gentle to moderate winds and seas of 2-5 ft prevail.

For the forecast, long period north to northeast swell moving
through the Tropical N Atlantic waters and Caribbean passages will
subside Thu. Moderate to fresh trades will prevail in the south-
central Caribbean, locally strong at times offshore northern
Colombia and northwest Venezuela, with moderate or weaker winds
elsewhere through the week.

...ATLANTIC OCEAN...

Please read the Special Features section for details on Hurricane
Nigel and on an Atlantic Gale Warning. In addition, please read
the Tropical Waves and Monsoon Trough/ITCZ sections for details on
convection in the Atlantic Ocean.

A stationary front extends from 31N68W to near Melbourne,
Florida. The combination of this front and a very sharp upper-
level trough over its vicinity is leading to numerous moderate to
strong convection from 22N to 31N between 72W and 80W. A surface
trough extends from around 28N73W through the NW Bahamas, locally
enhancing convection further. Moderate to fresh NE winds are N of
the front. Another surface trough extends from 31N50W to 24N58W,
but is not producing any convection. Otherwise, weak ridging
dominates W of 50W. To the E, a surface trough extends from 21N48W
to 16N44W. A small cluster of convection associated with this
feature is noted within about 90 nm of 18N47W. Moderate to fresh
trades are evident from 17N to 27N between the coast of Africa and
50W between a ridge N of that area and three tropical waves along
the monsoon trough/ITCZ. Locally strong winds are occurring off
the coast of Western Sahara. Seas in the broad zone of tradewinds
are 7 to 9 ft. Across the remainder of the basin, gentle to
moderate winds and 4-7 ft seas prevail, except 6 to 9 ft seas in
northerly swell related to Nigel N of 28N between 48W and 65W.

For the forecast W of 55W, the stationary front will transition to
a warm front Fri as low pressure develops along it to the east of
northern Florida, where frequent wind gusts to gale force are
likely late Thu into Fri. This non-tropical area of low pressure
could acquire some subtropical characteristics on Friday while it
moves generally northward. Regardless of development, this low is
likely to bring gusty winds to gale force, heavy rain, and high
surf to portions of the Southeast and Mid-Atlantic United States
late this week and into this weekend.

$$
KONARIK
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