[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251713
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

Hurricane Tammy is centered near 26.6N 59.3W at 25/1500 UTC or
450 nm SE of Bermuda, moving NE at 11 kt. Estimated minimum
central pressure is 965 mb. Maximum sustained wind speed is 90
kt with gusts to 110 kt. Peak seas near the center are estimated
at 31 ft. Numerous moderate to strong convection is noted within
90 nm S and 30nm N semicircles of the center. Similar convection
is also noted in an outer band from 23N to 29.5N between 55W and
58W. in the east semicircle and 120 nm in the west. Tammy is
moving toward the northeast. A northward turn is expected later
today, followed by a slower northwestward motion on Thursday and
Friday. Some additional strengthening is possible today, followed
by weakening through late this week. Tammy is forecast to become a
powerful post-tropical cyclone by 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
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 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 1031 mb centered over the eastern
United States and Hurricane Tammy will continue to 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, through Friday. A
recent altimeter pass indicates seas of 9 to 12 ft between 65W
and 70W while satellite derived wind data confirmed the presence
of N to NE winds of 20 to 30 kt. 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 10N14W, then continues westward to near 07N30W. The ITCZ
extends from 07N30W to 08N43W, then continues west of a surface
trough from 09N48W to 11N60W. The surface trough extends from
14N43W to 07N45W. A cluster of moderate to isolated strong
convection is noted from 08N to 10N between 20W and 25W.Scattered
moderate to isolated strong convection is seen elsewhere from 04N
to 12N between 15W and 34W. Similar convective activity is also
observed from 08N to 11N between 50W and 60W.

...GULF OF MEXICO...

A strong high pressure of 1031 mb centered over the eastern United
States extends a ridge across the Gulf of Mexico bringing mostly
dry conditions. An area of showers with embedded thunderstorms is
over the SW Gulf, including the Veracruz area, and also near the
coast between Tuxpan and Tampico. Patches of low level clouds,
with possible showers, are noted elsewhere. Under the influence of
this high pressure, moderate to fresh E to SE winds and seas of 4
to 7 ft prevail across the Gulf of Mexico, except for the eastern
Gulf and the Straits of Florida where fresh to strong NE to E
winds are found. Seas of 8 to 11 ft are forecast in the Straits of
Florida with these wind speeds.

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...

Divergence aloft is leading to an area of showers and
thunderstorms in portions of the NW Caribbean, particularly from
15N to 19N, W of 80W. This convective activity is affecting the
Gulf of Honduras, the northern part of Honduras and southern
Belize. Scattered showers and thunderstorms are over the SW
Caribbean S of 11N E of 80W due to the eastern extension of the
east Pacific monsoon trough. Similar convective activity is also
noted over parts of Jamaica and Hispaniola and regional waters to
about 16N.

A strong high pressure of 1031 mb centered over the eastern United
States is building southward toward the northwest Caribbean, and
this is leading to increasing NE winds in the lee of Cuba, and in
the Windward Passage. Fresh to locally strong winds and seas of
5 to 7 ft are present in these areas. Light to gentle winds are
noted over the eastern Caribbean with seas of 2 to 4 ft, except 5
to 7 ft across the Caribbean passages due to long period swell
generated by Hurricane Tammy to the north. Elsewhere, gentle or
lighter winds and seas of 2 to 3 ft are present.

For the forecast, fresh to occasionally strong winds will prevail
in the NW and north-central Caribbean through the week. Gentle
winds will prevail elsewhere.

...ATLANTIC OCEAN...

Please read the Special Features section at the beginning about
Hurricane Tammy as well as rough seas that are developing over
much of the western Atlantic to the W of Hurricane Tammy.

Aside from the impacts from these two features, to the E of 55W,
high pressure of 1025 mb centered south of the Azores near 31N26W
is dominant. Gentle to moderate winds prevail across the basin
east of 55W with seas 5 to 7 ft. Locally fresh NE winds are
occurring offshore Africa between the Cabo Verde and Canary
Islands.

For the forecast W of 55W, Tammy will move to 28.2N 58.8W this
evening, become extratropical and move to 29.8N 59.5W Thu morning,
30.5N 60.7W Thu evening, weaken as an extratropical cyclone near
31.0N 61.8W Fri morning, 31.2N 62.2W Fri evening, and 31.4N 62.7W
Sat morning. Tammy will change little in intensity as it moves to
near 31.7N 63.0W early Sun. A frontal boundary from 31N55W to the
central Bahamas will dissipate today, but the gradient between
Tammy and the decaying front combined with high pressure building
N of the area will support a broad area of strong NE winds and
rough seas across much of the area this week, mainly W of where
the frontal boundary currently resides.

$$
GR
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