[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171756
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Apr 17 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 32N. 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...

Gulf of Mexico Gale Warning: As of 1200 UTC, a cold front and an
attendant 1008 mb low moved off the Texas coast into the Gulf of
Mexico. The front will move southward across the basin bringing
strong winds and building seas. An area of gale force northerly
winds is expected to develop offshore of the Tampico area
tonight, behind the front. Seas will build to 12 ft in that
area, before winds and seas diminish beginning Sunday morning.
Please read the latest NWS 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...

The monsoon trough enters the Atlantic ocean through the coast
of Guinea-Bissau in West Africa near 10N15W and continues
southwestward to 02N25W. The ITCZ continues from 02N25W to the
coast of Brazil in South America near 00N47W. Scattered moderate
to strong convection is seen 400 nm south of the monsoon trough
between 10W-20W. Scattered showers are noted in the vicinity of
the ITCZ.

GULF OF MEXICO...

Please see the Special Features section for details on the Gale
Warning in effect for the west-central Gulf of Mexico.

As of 1545 UTC, a nearly stationary front over the Florida
Peninsula transitions to a warm front near 29N86W and connects
with a 1010 mb low south of the Louisiana coast near 29N91W. To
the southwest, a cold front extends southward to near Tampico,
Mexico. Scattered showers and isolated thunderstorms are located
behind the front extending from South Texas northeast to central
Louisiana near 29N90W. In the Bay of Campeche, an area of low
pressure is centered near 21N96W with a surface trough extending
from 22N94W to 19N97W. Scattered showers are noted in the
vicinity of the surface trough. Fresh to strong with few gusts
to gale force winds are occurring along the Texas coast behind
the front, with generally moderate SE winds elsewhere. Seas
ranged between 2 to 6 ft across the basin.

A cold front currently moving across the Texas coastal waters
will reach from near Panama City, Florida to 23N95W to the far
southwest Bay of Campeche by this evening. Winds will briefly
reach gale force near Tampico, Mexico tonight west of the front.
The front will stall from near Tampa Bay, Florida to the central
Bay of Campeche by early next week.
Looking ahead, reinforcing cool and dry air will push the front
into the far southeast Gulf through mid-week.

CARIBBEAN SEA...

Current satellite imagery shows very little of ash cloud from
the latest eruption of La Soufriere volcano on Saint Vincent
yesterday morning. The ashfall advisory for the Caribbean waters
west of the Windward Islands has been allowed to expire.
Additional eruptions are possible at any time. The volcano
remains in a continually active state, and additional eruptions
and ash plumes are possible at any time. Mariners transiting the
nearby waters should exercise caution, and are encouraged to
report volcanic ash to the National Hurricane Center by calling
305-229-4424.

Fresh trade winds prevail over the south-central and eastern
Caribbean, with moderate trades in the north central Caribbean.
Scatterometer data reveals an area of fresh to strong SE winds
offshore of Honduras and Belize, with moderate SE winds
elsewhere in the northwest Caribbean. Seas of 3-6 ft are over
most of the basin, except near the Gulf of Honduras with seas
near 8 ft and seas up to 7 ft north of Venezuela near the ABC
Islands.

For the forecast, a ridge extends along 23N through western Cuba.
Fresh to strong SE winds will persist north of central Honduras
through Sun, between the ridge and lower pressure over the
southwest Gulf of Mexico. The ridge will shift east ahead of a
weak front moving into the Gulf allowing trade winds to increase
over mainly the south-central Caribbean early next week.

ATLANTIC OCEAN...

A slowing cold front extends from a 1010 mb low pressure near
31N73W to 29N76W, where it transitions to a stationary front to
a second area of low pressure near Floridas Big Bend.
Thunderstorms continue within 120 nm of the Florida coast, along
this boundary. A cold front extends southwest to the low
southwest of Bermuda and remains north of 29N. At this time,
scattered showers are seen out to 100 nm on either side of the
boundary. Winds are moderate and W to the W of 70W with seas 3-5
ft.

Elsewhere, ridging from high pressure dominates supporting gentle
to moderate anticyclonic flow north of 20N and west of 55W. Winds
south of 20N are mainly fresh to locally strong southeasterlies
with seas 6-8 ft. Seas north of 29N range from 7-9 ft. A surface
trough is noted from 29N37W to 23N55W, with scattered moderate
convection from 21N-26W between 45W to 56W.

For the forecast, the boundary will fluctuate to the north and
south over the waters between roughly Bermuda and northeast
Florida through early next week, as a ridge persists across the
central Bahamas. Looking ahead, the ridge will shift east by
mid-week ahead of a slightly stronger frontal
boundary moving off the southeast U.S. coast by late Wed.

Torres/Christensen
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