[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201048
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 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 0600 UTC surface analysis and satellite imagery through
0940 UTC.

...SPECIAL FEATURE...

A non-tropical low pressure system has developed within a broad
area of cloudiness and thunderstorms near 31.5N55W, or about 600
miles east-southeast of Bermuda overnight. The low is expected to
develop gale-force winds later today while it moves generally
northward. The low is forecast to then move westward and
southwestward over warmer waters on Friday, and will likely become
a short-lived subtropical cyclone near and to the northeast of
Bermuda on Friday. The system is then expected to move toward the
north and northeast into a more hostile environment by late
Sunday into Monday.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of Guinea
near 11N15W to 05N27W. The ITCZ continues from 05N27W to 03N40W
to 03N51W. Scattered moderate to strong convection is noted from
03.5N to 07.5N between 17W and 23W, and within 180 nm N of the
ITCZ between 33W and 51W.

GULF OF MEXICO...

High pressure remains stationary across the middle Atlantic
states of the U.S. and extends SW to the NE Gulf this morning. The
pressure gradient between this ridge and low pressure across
northern Mexico is producing fresh to strong E to SE winds across
most of the Gulf north of 20N and E of 94W. These prevailing winds
are producing rough seas across this area of 7 to 10 ft, including
the Straits of Florida. An energetic upper level trough extending
from Texas southeastward into the NW Gulf continues to sustain
strong and very active convection across the W central Gulf,
along an eastward moving squall line that extends from the central
Louisiana coast near 92W to 25N92W to 19N95W. The southeast
portion of this line of convection is moving southeastward while
the north portion is moving slowly east. Overnight altimeter data
showed seas of 10 to 17 ft along and behind the line, and were
likely generated from strong gale force winds produced by these
strong thunderstorms. To the west of this activity, a surface
trough stretches across the Texas coastal waters.

Strong to near severe thunderstorms are expected to continue
across the NW and N central Gulf of Mexico through Fri and will be
capable of producing gale force winds and seas in excess of 12
ft. Meanwhile, a strong ridge stretching from eastern seaboard to
the NE Gulf will continue to dominate the Gulf waters 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 tonight 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...

Fresh to strong tradewinds are noted across the south central
Caribbean south of 16N, where seas are 5 to 8 ft. Fresh to strong
winds also prevail across the Gulf of Honduras south of 19N. Fair
and stable atmospheric conditions generally prevail across the
basin under the influence of middle level troughing and very
strong upper level westerly winds. Isolated showers and
thunderstorms area noted across the coastal waters of Nicaragua
and across the western coastal waters of Cuba north of 21N.

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 on
Fri and Sat. Expect fresh to strong easterly winds in the Gulf of
Honduras mainly at night through tonight.

ATLANTIC OCEAN...

A cold front extends from a newly formed 1013 mb low pressure
center near 31.5N55W to 25N60W where it becomes stationary and
continues into the SE Bahamas. Strong SE winds were captured by an
overnight scatterometer data to the southeast of the low to 29N
and to 48W. Persistent high pressure centered across North
Carolina extends southward to the front, and is producing fresh to
strong easterly winds north of the stationary front from about 68W
to Florida and through the Straits of Florida. Seas across this
area have built 8 to 10 ft. Scattered moderate isolated strong
convection is seen along and within 210 nm southeast of the front
to the east of 60W, and also south of the stationary front to 20N.

The low pressure center near 31.5N55W will move north to
northeastward today and interact with deep layered low pressure
across the NW Atlantic over the next few days, and has a medium
chance of gradually becoming a subtropical cyclone near or east of
Bermuda. See the special features section above for more
information.

East of the front and low, a surface ridge passes through 31N35W
to 25N46W to the coastal waters north of Hispaniola. The pressure
gradient south of the ridge is producing fresh tradewinds across
the Tropical Atlantic south of 15N to the east of 55W, where seas
are 6 to 8 ft.

The frontal boundary 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 continue to
support an area of fresh to strong easterly winds N of the front
and W of 68W through late Fri. Seas will peak around 10 ft E of
the Bahamas today. Large NE swell will enter the NE waters early
Sat and spread across the area waters through Mon.

$$
Stripling
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