[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 252333
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Thu Oct 26 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
2320 UTC.

...SPECIAL FEATURES...

Hurricane Tammy is centered near 28.0N 57.9W at 25/2100 UTC or
445 nm SE of Bermuda, moving NE at 12 kt. Estimated minimum
central pressure is 969 mb. Maximum sustained wind speed is 85 kt
with gusts to 105 kt. Peak seas near the center are estimated at
33 ft. Scattered moderate to strong convection is within 330 nm E
semicircle and 120 nm W semicircle. A northward turn is expected
tonight, followed by a turn to the west-northwest by Friday with a
decrease in forward speed. Steady weakening is expected for the
next few days. Tammy is forecast to become a powerful
extratropical cyclone by Thursday. Swells generated by Tammy will
continue to affect portions of Bermuda, the northern 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 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: A very tight pressure gradient
between strong high pressure of 1029 mb centered over the east
coast of North Carolina 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 18 ft across much of the area from 22N
to 31N, between the east coast of Florida and 60W, through Friday.
NOAA Buoy 41049 near 27.5N 63.0W has been reporting significant
wave heights of 15 to 20 ft continuously for the past 18 hours,
with the most recent observation 19 ft as of 25/2220 UTC. Recent
wind speeds at this buoy are 30 kt gusting to 35 kt. A recent
altimeter pass indicates seas of 10 to 14 ft between 70W and 74W
while earlier 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 06N30W. The ITCZ
extends from 06N30W to 09N44W, then continues west of a surface
trough from 09N49W to 11N60W. The surface trough extends from
14N45W to 08N46W. Scattered moderate convection is noted from 02N
to 14N between 18W and 34W, from 07N to 15N between 42W and 47W,
and from 10N to 13.5N between 50W and 60W.

...GULF OF MEXICO...

A strong high pressure of 1029 mb centered over the east coast of
North Carolina extends a broad ridge across the Gulf of Mexico
bringing mostly dry conditions. Isolated showers and tstorms are
over the Bay of Campeche in association with a surface trough.
Fresh east winds and 6 to 8 ft seas prevail across the Gulf. The
strongest winds and roughest seas are in the SE Gulf and Straits
of Florida, with fresh to strong winds and seas of 7 to 10 ft. An
altimeter pass from 25/1600 UTC provided evidence of 8 to 9 ft
seas from 25.5N to 27.5N between 86.5W and 87.5W.

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 scattered showers and thunderstorms
across the central Caribbean Sea from 14N to 19N between 68W and
80W, including portions of Jamaica and southern Hispaniola.
Showers and tstorms are more isolated across the NE Caribbean,
including Puerto Rico. Scattered moderate convection is noted
along the N coast of Honduras into the southern Gulf of Honduras.
South of 14N, isolated showers and t-storms are near the southern
Windward Islands. Scattered moderate to strong convection is along
the N coast of NW Venezuela and NE Colombia. Scattered moderate
convection is also noted in the SW Caribbean, off the coast of
Costa Rica.

Strong high pressure over the east coast of North Carolina is
leading to a very strong fetch of NE winds and rough seas over the
Atlantic, to the north of the Caribbean Sea. To an extent, these
conditions are affecting the northern Caribbean, north of 16N and
west of 67W, where fresh NE winds and 4 to 7 ft seas prevail,
including in the Mona and Windward Passages, as well as south of
Cuba and across the NW Caribbean. To the south of 16N, gentle
trades and 1 to 3 ft seas prevail.

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 occurring over
most of the western Atlantic to the W of Hurricane Tammy,
extending to the coast of Florida and the Straits of Florida.

Aside from the impacts from these two features, to the E of 50W,
high pressure of 1023 mb centered south of the Azores near 32N29W
is dominant. Gentle to moderate winds prevail across the basin
between 25W and 50W with seas 5 to 7 ft. Fresh NE winds are
occurring offshore Africa between the Cabo Verde and Canary
Islands.

For the forecast W of 55W, Hurricane Tammy will move to 29.5N
58.4W Thu morning, become extratropical and move to 30.5N 59.4W
Thu afternoon, weaken as an extratropical cyclone near 31.1N 60.4W
Fri morning, 31.5N 61.1W Fri afternoon, 31.8N 61.5W Sat morning,
and 32.1N 61.7W Sat afternoon. Tammy will change little in
intensity as it moves to near 32.5N 61.5W Sun afternoon. A frontal
boundary from 31N55W to the central Bahamas will dissipate
tonight, but the gradient between Tammy and the decaying front
combined with high pressure building N of the area will support a
continuation of the large area of strong to near gale NE winds
and very rough seas across much of the area through Fri. By the
weekend, the area of strong winds and rough seas will shrink to
be mainly between Florida and 70W, and north of 24N.

$$
Hagen
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