[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181054
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Sep 18 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
1045 UTC.

...SPECIAL FEATURES...

Recently upgraded Hurricane Nigel is centered near 26.5N 50.7W at
18/0900 UTC or about 810 nm ESE of Bermuda, moving NW at 10 kt.
Estimated minimum central pressure is 984 mb. Maximum sustained
wind speed is 70 kt with gusts to 85 kt. Satellite imagery shows
a wide convective banding feature consisting numerous moderate to
strong convection that extends from 27N to 29N between 47W-51W and
from 15N to 26N between 51W-53W. The band coils around a CDO
(Central Dense Overcast) type feature that consists of similar
convection from 24N to 26.5N and between 49W-52W. Scattered
moderate to isolated strong convection is from 26N to 27N between
47W-49W. Nigel is intensifying, and it is forecast to maintain
its present motion over the next couple of days, then is forecast
to turn northward late Tue, and accelerate northeastward through
the rest of the week. Peak seas to 26 ft extend outward from the
center for up to 210 nm in the NE quadrant. Rapid strengthening is
forecast during the next 48 hours. Nigel will likely become a
hurricane overnight, and is forecast to become a major hurricane
on Tue.

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.

...TROPICAL WAVES...

An central Atlantic tropical wave has its axis along 42W from 02N
to 12N, moving westward 10-15 kt. Scattered moderate convection is
within 60 nm west of the wave from 07N to 11N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal border of
Senegal and Guinea-Bissau to 09N23W to 07N30W to 05N39W. The
ITCZ extends from 05N43W to 05N50W. Scattered moderate to isolated
strong is south of the trough from 06N to 09N between the coast
of Africa and 20W, within 120 nm south of the trough between
30W-33W and within 30 nm north of the trough between 32W-34W.
Scattered moderate convection is north of the trough from 10N
to 12N between 28-39W.

...GULF OF MEXICO...

A surface trough extends from the east-central Florida southwest
to near Naples, Florida. Otherwise, relatively week high pressure
is over the area. The associated gradient supports generally
light to gentle northeast to east winds over the area, except
for moderate north winds north of 28N and east of 89W. These
winds are behind a frontal trough that is moving across the NE
Gulf. Scattered showers and a few thunderstorms are over eastern
Bay of Campeche. Isolated showers and thunderstorms are noted
from 22N to 27N between 90W-97W and from 25N to 29N between
83W-90W. Wave heights are 1-2 ft over the area.

For the forecast, a weak trough just inland the Texas coast will
be replaced by another weak trough on Mon that will move off the
Texas coast and over NW Gulf. The trough is expected to be
accompanied by a wind shift along with a few showers and
thunderstorms. Winds will be moderate or weaker with slight seas
through Thu, pulsing to moderate to fresh offshore the western
Yucatan in the evenings. Winds may freshen in the NE Gulf by the
end of the week due to building high pressure north of the area
with seas also building.

...CARIBBEAN SEA...

An upper-level northeast to southeast oriented trough extends
from NW Cuba toward the NE Caribbean Sea. Isolated showers and
thunderstorms are noted north of 16N and west of 70W. The monsoon
trough is along 09N/10N from 73W in Colombia, beyond Costa Rica.
Scattered to numerous moderate to strong convection is confined
to the southwestern Caribbean south of 12N between 76W-81W.

Moderate and fresh northeast to east winds are between 63W and
the Windward Passage, and reaching the coast of Central America,
during the last 24 hours. Gentle to moderate northeast to east
winds are west of 75W to the coast of Central America. Wave
heights are 2 ft on the Atlantic side of the eastern Caribbean
Sea islands, from 3-4 ft east of 80W, except for 4-5 ft to the
north of Panama, 2 ft off the coast of southeastern Nicaragua
and 1 ft over the rest of the Sea.

For the forecast, long period north to northeast swell may impact
the Caribbean passages and Tropical N Atlantic through the early
part of the week. Moderate to fresh trades will prevail in the
central Caribbean, locally strong at times offshore northern
Colombia, with moderate or weaker winds elsewhere through the
week.

...ATLANTIC OCEAN...

Please read the Special Features Section for details about
Hurricane Nigel.

Fresh to strong NE winds are from 20N northward from 30W
eastward. Mostly moderate to some fresh northeast winds are
elsewhere north of 10N and east of 40W. Moderate to fresh
southeast to south winds are north of 24N and east of 69W.
Moderate southerly winds are south of the monsoon trough/ITCZ and
east of 50W. The wave heights range from 7-9 ft north of 20N and
west of 60W, and north of 22N east of 35W as noted in altimeter
data passes. Higher wave heights of 10-12 ft are near the coast
of Africa, where a tight pressure exists between strong high
pressure and lower pressure in western Africa. Wave heights of
4-7 ft are over the rest of the Atlantic.

Isolated showers and thunderstorms are seen from 10N to 20N
between 40W-47W, and from 20N to 22N between 27W-32W.

For the forecast W of 55W, Hurricane Nigel is near 26.5N 50.7W at
5 AM EDT, and is moving northwest at 10 kt. Maximum sustained
winds are 70 kt with gusts to 85 kt, and the minimum central
pressure is 984 mb. Nigel will continue strengthen as it moves to
near 27.6N 51.8W this afternoon with maximum sustained winds 85 kt
gusts 105 kt, to near 29.1N 53.3W late tonight with maximum
sustained winds 100 kt gusts 120 kt, to near 30.8N 54.6W Tue
afternoon and maintain intensity as it moves to north of the area
near 33.1N 55.0W late Tue night. Nigel is forecast to gradually
weaken as it accelerates northeastward farther away from the area
through the rest of the week. A cold front along the southeastern
United Stated coast will reach from near 31N72W to near Jupiter,
Florida Tue morning, then stall over the northern forecast waters
through the end of the week. Winds and seas may increase west of
the stalled boundary by the end of the week as a tight pressure
gradient develops due to building high pressure inland and a
developing coastal trough off the Carolinas.

$$
Aguirre
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