[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201731
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Fri Oct 20 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...

Newly upgraded Hurricane Tammy is centered near 14.1N 58.6W at
20/1500 UTC or 140 nm ESE of Martinique, moving WNW at 6 kt.
Estimated minimum central pressure is 992 mb. Maximum sustained
wind speed is 65 kt with gusts to 80 kt. Peak seas are currently
around 21 ft.
Tammy has numerous moderate to isolated strong convection
observed from 08N to 16.5N and between 54W and 60W. Tammy
general motion is expected to continue through this afternoon. A
turn toward the northwest is anticipated by this evening,
followed by a north-northwestward and northward turn Saturday
night through Sunday night. On the forecast track, the center of
Tammy will move near or over portions of the Leeward Islands
tonight and on Saturday, and then move north of the northern
Leeward Islands on Sunday. Gradual strengthening is forecast
during the next couple of days, and Tammy is expected to be a
hurricane while it moves near or over portions of the Leeward
Islands. Heavy rains from Tammy will begin to affect the Leeward
and northern Windward Islands later today and into Saturday
morning, spreading into the British and U.S. Virgin Islands and
Puerto Rico as early as Sunday.  This rainfall may produce
isolated flash and urban flooding, along with isolated mudslides
in areas of higher terrain. Swells generated by Tammy will
continue to affect portions of the Lesser Antilles during the
next few 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 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.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Guinea-Bissau near 11N16W and continues to 07N24W and then to
08N31W. The ITCZ extends from 08N31W to 10N37W to 07N44.5W.
Scattered moderate convection is observed from 01.5N to 11N east
of 24W and between 30W and 38W.

...GULF OF MEXICO...

A weak surface trough extends from 26N91W to 20N93W and is void
of significant convection. The rest of the basin is under a weak
high pressure pattern and a dry airmass that suppresses the
development of showers and thunderstorms. Moderate or weaker
winds prevail across the Gulf, with seas of 3-4 ft in the SE
Gulf and 1-3 ft elsewhere.

For the forecast, high pressure from the northern Gulf coast into
South Carolina will shift SW through Sat, allowing a cold front
to sag into the NE Gulf. This front will dissipate as it moves
across the eastern Gulf through Sat. Another cold front will
follow, moving across the eastern Gulf Sun night through Mon,
before stalling southeast of the region by Mon night into early
Tue. Looking ahead, high pressure building in the wake of the
front will support moderate to fresh E winds Sun night through
mid week.

...CARIBBEAN SEA...

Please see the Special Features section above for more details on
Hurricane Tammy located just east of the Lesser Antilles.

A surface trough extends from western Cuba to Belize and is
producing scattered moderate convection within 65 nm of its
axis. Meanwhile, the eastern Pacific monsoon trough enters the
SW Caribbean Sea near 11N83W and continues eastward to northern
Colombia near 10N77W. Scattered moderate to isolated strong
convection is evident on satellite imagery south of 13N. No deep
convection is present elsewhere in the Caribbean.

Moderate easterly trade winds and seas of 3 to 5 ft are found in
the south-central Caribbean. Outside of the influence of Tammy,
moderate or weaker winds and 2 to 4 ft seas are prevalent in the
rest of the basin.

For the forecast, newly upgraded Hurricane Tammy is near 14.1N
58.6W at 11 AM EDT, and is moving west-northwest at 6 kt.
Maximum sustained winds are 65 kt with gusts to 80 kt, and the
minimum central pressure is 992 mb. Tammy will move through the
northern Leeward Islands through early Sun, reaching 15.1N 59.8W
this evening, 16.4N 60.9W Sat morning, 17.9N 61.9W Sat evening,
and 19.3N 62.7W Sun morning before continuing north of the area
through the early part of the week. Elsewhere, a trough will
persist over the northwest Caribbean into Sat. Looking ahead, a
weak cold front will move into the northwest Caribbean by late
Mon, then stall and weaken from eastern Cuba to northern Belize
Tue.

...ATLANTIC OCEAN...

Please see the Special Features section above for more details on
Hurricane Tammy located just east of the Lesser Antilles.

A surface trough enters the tropical Atlantic near 31N61W and
continues southwestward to 28N72W. Farther west, another surface
trough stretches from 31N76W to 24N79W. These two features
combined with divergent flow aloft is resulting in a broad area
of scattered moderate convection N of 23.5N and W of 65W.
Another area of scattered moderate convection is depicted north
of Puerto Rico and it is associated with a deep layer trough.

The subtropical ridge centered near 30N36W is the main feature of
interest in the central and eastern Atlantic outside of the deep
tropics. The pressure gradient between this high pressure and
Tammy sustain moderate to fresh E-SE winds from 20N to 31N and
between 53W and 67W. Seas in these waters are 6-10 ft. A cold
front extends from Morocco to 27N38W and is producing no
convection. N of the boundary, moderate N winds and seas of 6 to
10 ft area present. Across the remainder of the basin, winds are
mainly moderate with seas of 4 to 7 ft.

For the forecast W of 55W, newly upgraded Hurricane Tammy is
near 14.1N 58.6W at 11 AM EDT, and is moving west-northwest at 6
kt. Maximum sustained winds are 65 kt with gusts to 80 kt, and
the minimum central pressure is 992 mb. Tammy will move through
the northern Leeward Islands through early Sun, reaching 19.3N
62.7W Sun morning, then continuing northward to 20.6N 63.3W Sun
evening, and 22.0N 63.3W Mon morning, and 24.4N 61.4W by early
Tue. Farther west, a weak cold front will move off the northeast
Florida coast overnight, then weaken as it moves eastward over
the waters north of 27N, before stalling and dissipating east of
Bermuda early in the week. A second front will follow, moving
off the northeast Florida coast late Sun, reach from Bermuda to
West Palm Beach, Florida by early Mon, then stall along 21N Tue.

$$
KRV
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