[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201740
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu May 20 2021

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
1640 UTC.

...SPECIAL FEATURE...

A 1012 mb non-tropical low is located about 600 NM east of
Bermuda.  The low is expected to develop gale-force winds later
today while it moves generally northward. The low is then
forecast to move westward and southwestward over warmer waters
tonight and Friday, and it will likely become a subtropical
cyclone near and to the northeast of Bermuda on Friday. The
system is expected to move toward the north and northeast into a
more hostile environment by late Sunday into Monday. Currently S
strong winds are associated with the low in our marine area
north of 29N between 46W and 52W with seas to 9 ft. These
conditions should diminish south of 31N by tonight. For more
information on this developing low pressure area, please see
High Seas forecasts issued by the NOAA Ocean Prediction Center
ocean.weather.gov/shtml/NFDHSFAT1.php.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coast of Senegal near
14N16W to 10N22W. The ITCZ continues from there to 04N52W along
the coast of NE Brazil. Scattered moderate convection is noted
between 01N and 06N west of 43W.

GULF OF MEXICO...

Scattered moderate convection is occuring north of 20N between
90W and 96W in association with a sharp upper-level trough over
Texas and NE Mexico as well as a surface trough over the NW Gulf
from 25N94W north-northwestward to the Texas coast near 29N95W.
While the prevailing winds are gentle or weaker west of the
trough, winds will be gusty in the vicinity of the thunderstorm
activity. East of the trough and north of 23N, a strong NE-SW
pressure gradient is forcing E to SE winds of fresh to strong.
Seas are 8 to 10 ft in the NE Gulf as well as the Straits of
Florida. Elsewhere seas are generally 5 to 7 ft.

Strong thunderstorms are expected to continue across W Gulf of
Mexico through Fri and will be capable of producing locally near-
gale force winds and seas to 10 ft. Meanwhile, a strong ridge
stretching from eastern seaboard to the NE Gulf will continue to
dominate the Gulf waters through the remainder of the week. The
pressure gradient between the ridge and deepening low pressure
across the Southern Plains and northern Mexico will result in
fresh to strong SE winds and high seas across the Gulf region
through Sat. Seas will peak 10 to 13 ft today through Fri in the
Straits of Florida and 12 ft in the N central Gulf on Fri.

CARIBBEAN SEA...

A moderate N-S pressure gradient between ridging north of the
Bahamas and a 1010 mb Colombian low is promoting fresh to strong
E winds over the S central Caribbean and over the Gulf of
Honduras. Elsewhere the trades are gentle to moderate.  Seas are
peaking 6-8 ft just north of Colombia and 5-7 ft in the Gulf of
Honduras. Elsewhere seas are generally 4-6 ft. Scattered showers
are present across the N Caribbean and Greater Antilles in
association with a stationary front that extends over the SE
Bahamas to central Cuba. Elsewhere very scattered moderate
convection is noted south of 12N in the SW Caribbean in
association with the NE Pacific monsoon trough that extends from
Costa Rica to NE Colombia.

High pressure off the U.S. East Coast will continue to build
across the western Atlantic west of 70W through Fri. This will
bring fresh to strong winds across the central Caribbean through
Sat. Fresh to strong winds will also occur in the lee of Cuba
through Sat. Expect fresh to strong easterly winds in the Gulf
of Honduras mainly at night through tonight.

ATLANTIC OCEAN...

See above Special Feature for a non-tropical low centered just
north of our marine area of responsibility.

A cold front extends from the 1012 mb non-tropical low at 33N52W
southwestward to 22N70W where it transitions to a stationary
front to 23N79W. Scattered moderate convection is located within
120 NM southeast of the front east of 65W and scattered showers
are present within 120 NM south of the front west of 65W. Strong
ridging north of the front is causing fresh to strong NE to E
winds between 19N and 30N west of 70W. Seas are up to 9 ft east
of the Bahamas and NE Florida. Elsewhere across the tropical N
Atlantic, the NE to E trades are moderate to fresh south of 20N
and gentle elsewhere. Seas are up to 8 ft south of 20N and 4 to
7 ft elsewhere.

In the forecast west of 65W, the front will weaken and dissipate
through Fri as it sinks southward and approaches the Windward
Passage and Hispaniola. Meanwhile, the pressure gradient between
high pressure off the eastern seaboard and the frontal boundary
will support an area of fresh to strong easterly winds N of the
front and W of 68W through late Fri. Seas will peak around 9 ft
E of the Bahamas today. Large NE swell will enter the NE waters
early Sat and spread across the area waters through Mon.

In the forecast east of 65W, winds and seas are anticipated to
have little change through Saturday, then diminish slightly on
Sunday and Mon.

$$
Landsea/Rivera-Acevedo
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