[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242337
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Wed Oct 25 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
2300 UTC.

...SPECIAL FEATURES...

Hurricane Tammy is centered near 24.6N 61.7W at 24/2100 UTC or
490 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 scattered strong convection is seen
within 210 nm of the center in the E semicircle and 120 nm W
semicircle. Scattered moderate convection also extends out well to
the NE of the center, just southeast of a cold front, which is
situated to the north of Tammy. A general northeastward 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 Thursday night or 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.

Western Atlantic Very Rough Seas: The tightening pressure
gradient between strong high pressure of 1030 mb over the east
coast of United States and Hurricane Tammy will support a large
area of strong to near-gale force NE winds and very rough seas of
12 to 17 ft across much of the area from 22N to 31N, between the
east coast of Florida and 60W, now 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 09N13W, then continues westward to near 06N23W. The ITCZ
extends from 06N23W to 09N39W, then continues west of a surface
trough, that runs from 13N41W to 06N42W, from 08.5N43.5W to
10N60W. Scattered showers and isolated tstorms are found within
300 nm of the monsoon trough and ITCZ.

...GULF OF MEXICO...

High pressure of 1030 mb over the east coast of United States
extends ridging into the Gulf of Mexico bringing mostly dry
conditions. Under the influence of this high pressure, fresh E to
SE winds and seas of 4 to 7 ft prevail across the Gulf of Mexico.

For the forecast, high pressure north of the area will support
fresh winds, fresh to strong in the E Gulf, through the remainder
of the week, with seas of 6 to 8 ft across the basin.

...CARIBBEAN SEA...

Weak 1009 mb low pressure associated with the remnants of Tropical
Depression Twenty-One is centered over south-central Honduras.
Scattered moderate isolated strong convection prevails across the
western Caribbean, mainly west of 80W. Additional convection is
firing along and just inland from the coast of northern Colombia.
A few showers and tstorms are also noted over Hispaniola.

High pressure of 1030 mb over the east coast of the United States
is building southward across Cuba and Hispaniola into the
northern Caribbean Sea. Moderate to fresh NE winds are present in
the NW Caribbean, north of 17N and west of 73W, including in the
Windward Passage. Seas are 5 to 7 ft in this area. Elsewhere,
gentle winds and seas of 2 to 3 ft are present.

For the forecast, fresh to occasionally strong winds will prevail
in the lee of Cuba and in the Windward Passage through the week.
Fresh NE winds will also develop S of Hispaniola late this 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 31N54.5W to 25N68W to across the NW
Bahamas to 25N80W. Strong high pressure of 1030 mb over the east
coast of United States follows the front. Hurricane Tammy lies to
the south of the front. Strong NE winds and 9 to 13 ft seas
prevail behind the frontal boundary, and across most of the area
from 24N to 31N between 63W and 80W. The area just off NE Florida
is experiencing fresh ENE winds and 6 to 8 ft seas. South of 22N
between 60W and the SE Bahamas, moderate to fresh winds and 5 to 9
ft seas prevail. Scattered moderate convection is within 180 nm SE
of the cold front, to the NE of Tammy, covering the area from 26N
to 30N between 52.5W and 60W.

The remainder of the Atlantic, east of 55W, is under the influence
of a 1023 mb high pressure centered near 32N28W. Due to the high
pressure, gentle to moderate winds prevail across the basin east
of 55W with seas 5 to 7 ft. The exception is over the far E
Atlantic, east of 21W, from 21N to 30N, where fresh NE to E winds
and 7 to 8 ft seas prevail.

For the forecast W of 55W, Hurricane Tammy will move to 25.6N
60.7W Wed morning, 27.5N 59.6W Wed afternoon, 29.2N 59.4W Thu
morning, weaken as an extratropical cyclone near 30.4N 60.3W Thu
afternoon, 31.1N 61.2W Fri morning, and 31.6N 62.2W Fri afternoon.
Tammy will change little in intensity as it moves to near 32.0N
63.4W Sat afternoon. The cold front extending from 31N55W to the
central Bahamas will stall and 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 strong
to near gale force NE winds and rough seas across much of the
area west of the frontal boundary Tue through the week.

$$
Hagen
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