[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 241709
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Oct 24 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 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

Hurricane Tammy is centered near 24.2N 62.3W at 24/1500 UTC or
500 nm SSE of Bermuda, moving NE at 7 kt. Estimated minimum
central pressure is 987 mb. Maximum sustained wind speed is 65
kt with gusts to 80 kt. Peak seas near the center are estimated
at 27 ft. Numerous moderate to strong convection is seen within
120 nm NE quadrant of the center. Similar convective activity is
also noted in an outer band from 21N to 25N between 59W and 61W.
Tammy is moving toward the northeast, and this general motion is
expected to continue through Wednesday. A turn toward the north at
a slower forward speed is forecast to begin on Thursday, followed
by a bend to the northwest on Friday. Slight strengthening is
possible during the next day or so followed by steady weakening.
Tammy is forecast to become a post- tropical cyclone on Thursday.
Swells generated by Tammy will continue to affect portions of the
Leeward Islands, the British and U.S. Virgin Islands, and Puerto
Rico during the next few days. These swells are likely to cause
life-threatening surf and rip current conditions. Please read the
latest HIGH SEAS FORECAST issued by the National Hurricane Center
at the website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and
the latest Tammy NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Depression Twenty-One has dissipated inland over Nicaragua,
and the National Hurricane Center issued the last advisory on
this system at 24/1500 UTC. At this time, the remnants of Twenty-
One are centered near 13.6N 84.8W or 110 nm NNW of Bluefields
Nicaragua, moving WNW at 3 kt. Estimated minimum central pressure
is 1007 mb. Maximum sustained wind speed is 20 kt with gusts to 25
kt. Clusters of numerous moderate to strong convection are
occurring from 10N to 13N between 80W and 85W. The remnants are
moving toward the west-northwest and a gradual turn toward the
west is expected soon. The remnants of the tropical depression are
expected to produce additional rainfall totals of 4 to 8 inches
with maximum amounts of 12 inches across Nicaragua and 2 to 4
inches with maximum amounts of 6 inches across southern and
eastern Honduras. These rains are likely to produce flash and
urban flooding, along with mudslides in areas of higher terrain.
Please read the latest NHC Forecast/Advisory and Public Advisory
at www.hurricanes.gov for more details.

Western Atlantic Very Rough Seas: The tightening pressure gradient
between high pressure of 1030 mb over the east coast of United
States and Hurricane Tammy will support a large area of of strong
to near-gale force NE winds and very rough seas of 12 to 17 ft
across much of the area from 21N to 31N, between the east coast of
Florida and 60W, starting this afternoon and continuing through
Friday. Mariners should either seek to avoid this region, or use
extreme caution in this area, depending on your vessel type and
cargo. 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 more details.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic through the coast of Guinea
near 09N13.5W, then continues westward to near 06N23W. The ITCZ
extends from 06N23W to 08N38W, then continues west of a surface
trough, that runs from 13N39W to 07N40W, from 09N42W to 08N50W to
10N60W. Scattered moderate convection can be found from 07N to 11N
between 18W and 26W, from 06N to 12N between 34W and 47W, and
from 07N to 11N between 56W and 58W.

...GULF OF MEXICO...

High pressure of 1030 mb over the east coast of United States
extends into the Gulf of Mexico bringing mostly dry conditions.
A few showers and thunderstorms are noted over the SW Gulf and
over the NE Yucatan Peninsula. The latter is associated with a
surface trough that extends along 88W. Under the influence of the
above mentioned high pressure, moderate to fresh E to SE winds
and seas of 4 to 6 ft are observed over the E and central Gulf
while fresh southerly winds and seas of 5 to 7 ft dominate the
western Gulf.

For the forecast, high pressure north of the area will support
moderate to fresh winds, locally strong in the E Gulf, through the
remainder of the week.

...CARIBBEAN SEA...

Tropical Depression Twenty-One has dissipated inland over Nicaragua.
Please, see the Special Features section above for more information.

High pressure of 1030 mb over the east coast of United States is
building southward across Cuba and Hispaniola into the northern
Caribbean Sea. A surface trough, currently over the Yucatan
Peninsula, is generating scattered showers with embedded
thunderstorms over the NW Caribbean. A diffluent pattern aloft is
helping to induce this convective activity. A few showers and
thunderstorms are also noted over the central Caribbean, and the
Lesser Antilles.

Moderate to locally fresh NE winds are present in the lee of Cuba
and Windward Passage, with seas of 4 to 6 ft in the lee of Cuba.
Elsewhere, winds are light to gentle with 1 to 3 ft seas. The
exception is in the Mona and Anegada Passages, where swell from
distant Hurricane Tammy is causing seas of 4 to 6 ft.

For the forecast, fresh to occasionally strong winds will prevail
in the lee of Cuba and in the Windward Passage through the week.
Gentle winds will prevail elsewhere.

...ATLANTIC OCEAN...

Please read the Special Features section at the beginning about
Hurricane Tammy.

A cold front extends from 31N57W across the NW Bahamas into SE
Florida. Cold air stratocumulus clouds are seen on visible
satellite imagery in the wake of the front. Strong high pressure
of 1030 mb over the east coast of United States follows the front.
Recent scatterometer data provide observations of fresh to strong
northerly winds behind the frontal boundary, and mainly fresh N
to NE winds south of the front to the coast of eastern Cuba. Some
shower activity is over the SE Bahamas, the Turks and Caicos
Islands and eastern Cuba. Outside of the area being affected by
Tammy, seas are in the 6 to 9 ft range E of the Bahamas. The
remainder of the Atlantic forecast area is under the influence of
a 1025 mb high pressure located S of the Azores near 32N29W. This
system is producing a gentle to moderate anticyclonic flow. Seas
range from 4 to 7 ft over this area.

For the forecast W of 55W, Hurricane Tammy is near 24.2N 62.3W at
11 AM EDT, and is moving northeast at 7 kt. Maximum sustained
winds are 65 kt with gusts to 80 kt, and the minimum central
pressure is 987 mb. Tammy will move to 25.0N 61.2W this evening,
26.7N 59.9W Wed morning, 28.6N 59.1W Wed evening, 30.1N 59.5W Thu
morning, weaken as an extratropical cyclone near 31.2N 60.6W Thu
evening, and 31.8N 61.6W Fri morning. Tammy will change little in
intensity as it moves to near 32.5N 63.5W early Sat. A cold front
extending from 31N57W to the central Bahamas will stall tonight
then dissipate by Wed. The pressure gradient between this front,
Tammy, and high pressure building N of the area will lead to the
development of a broad area of NE winds and rough seas across much
of the area west of the frontal boundary Tue through the week.

$$
GR
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