[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172113
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Thu Mar 18 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 1800 UTC surface analysis and satellite imagery through
2100.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Africa near 12N15W to
02N25W. The ITCZ continues from 02N25W to 01N37W. Numerous
moderate and scattered strong convection is observed within 360 nm
of the coast of Liberia and Sierra Leone, east of 19W south of
07N.

GULF OF MEXICO...

A cold front is moving off the Texas coast and into the far
western Gulf of Mexico now, extending from 29N96W to 26N98W.
Ahead of the front, fresh to strong southerly winds prevail
across the central Gulf of Mexico, per an earlier ASCAT
scatterometer pass. Seas are 6-9 ft across the same waters. A
pre-frontal line of scattered showers and thunderstorms has
formed offshore of Texas and southwest Louisiana, mainly north of
27N, extending northward to the Texas/Louisiana border. This line
of thunderstorms will move from west to east across the northwest
to the north-central Gulf this evening. By midnight tonight local
time, the line of thunderstorms will be near the coast of
Mississippi and southeast Louisiana. Some of the thunderstorms to
the north of 28N are likely to be strong to severe, with frequent
lightning, gusty winds, small hail and isolated waterspouts.

Fresh to strong southerly flow will prevail through tonight ahead
of the cold front. The front will reach from the Florida
Panhandle to the central Bay of Campeche Thu morning, and from
southern Florida to the Yucatan peninsula Fri morning before
moving southeast of the basin Fri night. Brief gale-force NW
winds are expected near the Veracruz coast of Mexico midday Thu.
Fresh to strong N to NE winds and building seas are expected in
the northeast Gulf Sat night through Sun night.

CARIBBEAN SEA...

An earlier ASCAT scatterometer pass indicated the presence of a
surface trough in the southwest Caribbean from the southeast
coast of Nicaragua to the north coast of Panama near 09N80W. This
surface trough and a mid-level trough over the southern portion
of Central America are enhancing scattered moderate convection
over the southwest Caribbean from 10N-12N between 80W-84W. Heavy
rain could impact the southeast coast of Nicaragua through
tonight.

A cold front extends from west of the Azores through 32N35W to
Montserrat to just south of Puerto Rico and ending inland over
the Dominican Republic. Cloudiness with possible scattered showers
are within 45 nm either side of the front, including near
Antigua, Montserrat, St. Kitts and Nevis, and the Dominican
Republic. The cold front is forecast to drift SE across the
northeast Caribbean through Thu. A surface trough extends from
St. Lucia east-northeastward to 17N53W. Scattered showers are
possible near St. Lucia and Martinique.

An earlier ASCAT scatterometer pass showed moderate to fresh
winds covering most of the Caribbean, with strong NE to E winds
over the central Caribbean. Strong E to SE winds are also likely
occurring in the Gulf of Honduras. Seas are likely currently 7-11
ft in the central Caribbean, 5-8 ft in the eastern Caribbean and
4-7 ft in the NW Caribbean, except 5-8 ft in the Gulf of
Honduras.

Strong tradewinds will prevail across the central Caribbean
through Fri morning, with near gale-force winds expected near the
coast of Colombia each night. Fresh to strong winds are expected
in the Windward Passage tonight. SE winds will increase across the
NW Caribbean through tonight, ahead of a cold front moving into
the NW Gulf of Mexico. The front will move southeast across the
Yucatan Channel Fri night, then meander across the northwest
Caribbean and western Cuba through Sun. Large northerly swell will
affect the Tropical N Atlantic waters and Caribbean Passages
through Thu.

ATLANTIC OCEAN...

A cold front extends from 1015 mb low pressure northwest of
Bermuda near 35N70W to near Savannah, Georgia. Ahead of the
front, scattered moderate showers and isolated thunderstorms are
occurring from 29N-32N between 68W-76W, although this activity has
been dissipating somewhat in the past few hours. Fresh S to SW
winds are located in the same area. Gentle to moderate anticyclonic
winds prevail elsewhere north of 22N and west of 65W, due to
surface ridging. An exception is in the Straits of Florida, where
fresh SE winds were seen on earlier ASCAT scatterometer data.

A cold front extends southwestward across the central Atlantic
from west of the Azores through 32N35W to Montserrat to just
south of Puerto Rico and ending inland over the Dominican
Republic. The earlier ASCAT scatterometer data showed fresh NE
winds north of the front to 22N between 55W-77W. These winds are
locally strong just north of the Mona Passage. A pre-frontal
surface trough is analyzed from 28N40W to 18N47W. Cloudiness and
scattered showers are along the cold front and the surface
trough. Large NW to N swell of 8-16 ft associated with the cold
front covers the Atlantic west of a line from 32N28W to 20N40W to
14N61W and east of around 70W. Seas are 5-8 ft elsewhere east of
the Bahamas, in northerly swell.

For the forecast, the cold front extending from the Tropical N
Atlantic waters to the northeast Caribbean will drift southeast
and weaken through late Thu. Large northerly swell will affect the
waters east of 72W through Thu. The cold front north of Florida
will move east of northern Florida Thu night, extend from near
31N71W to the Straits of Florida Fri evening, then become
stationary on Sat. A new area of low pressure forming along this
stationary front will intensify northerly winds east of northern
Florida Sun and Sun night, with gale conditions possible.

$$
Lewitsky/Hagen
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