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Atlantic Tropical Weather Discussion



618 
AXNT20 KNHC 111202
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
702 AM EST Wed Dec 11 2019

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 0600 UTC surface analysis and satellite imagery through 
1100 UTC.

...SPECIAL FEATURES...

GULF OF MEXICO GALE WARNING...

A cold front is in the Gulf of Mexico, from 30N84W to 26N93W
into the Isthmus of Tehuantepec of southern Mexico. Expect NW-
to-N gale-force winds, and sea heights ranging from 10 feet to
15 feet, from 24N southward from the cold front westward. The 
gale-force wind event will last for the next 18 hour or so. 
Please read the latest HIGH SEAS FORECAST:
MIAHSFAT2/FZNT02 KNHC, the latest OFFSHORE FORECAST: 
MIAOFFNT4/FZNT24 KNHC, or go to the website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, everything from the NWS
National Hurricane Center, for more details.

...MONSOON TROUGH/ITCZ... 

The monsoon trough passes through the coastal areas of Sierra 
Leone near 08N13W to 06N17W. The ITCZ continues from 06N17W to 
04N23W, 02N26W, 02N30W, to the Equator along 32W, to the Equator
along 37W, to 01S40W. Precipitation: isolated moderate to locally
strong to the south and southeast of the line 09N13W 07N23W 
02N40W, to the Equator along 42W.

GULF OF MEXICO...

A cold front is moving through the Gulf of Mexico, from the
Florida Big Bend, into the north central Gulf of Mexico, straight
southward, into the Isthmus of Tehuantepec of southern Mexico,
and into the northernmost parts of the Gulf of Tehuantepec on the
Pacific Ocean side of southern Mexico. Expect NW-to-N gale-force 
winds, and sea heights ranging from 10 feet to 15 feet, from 24N 
southward from the cold front westward. The gale-force wind event 
will last for the next 18 hour or so. Precipitation: isolated
moderate within 75 nm on either side of the line that runs from 
the Florida Panhandle near 30N87W, to 27N90W, to 23N92W to 17N93W
in the Isthmus of Tehuantepec of southern Mexico.

The current cold front will stall from Tampa Bay to the Bay of 
Campeche by Thursday morning. The front will drift northward and 
weaken through Friday night. Gale-force NW to N winds will 
prevail to the west of the front, along the coast of Mexico, 
today.

CARIBBEAN SEA...

Broad surface low pressure covers the SW corner of the Caribbean
Sea. Satellite data and the GFS forecast for 250 mb show upper
level anticyclonic wind flow in the SW corner of the Caribbean
Sea. The GFS model forecasts show E-to-NE wind flow for 500 mb, 
and NE wind flow for 700 mb, across the same area. Precipitation:
isolated moderate rainshowers are from 15N southward from 78W 
westward.

An upper level trough starts in the Atlantic Ocean, near 24N55W,
and it continues to 20N61W, into the NE Caribbean Sea, to 18N62W,
and to 14N64W. Precipitation: Isolated to widely scattered
moderate from 15N to 20N between 55W and 65W. Comparatively drier
air in subsidence is apparent in water vapor satellite imagery, 
on the western side of the trough, elsewhere, from 14N to 20N 
between 62W and 70W.

The GFS model for 500 mb and for 700 mb shows cyclonic wind flow,
in the areas from Guyana northward, and around Trinidad and
Venezuela and the coastal waters. Precipitation: Widely scattered
to scattered moderate in the Atlantic Ocean and in the SE 
Caribbean Sea from 07N to 12N between 55W and 63W.

Rainshowers are possible in the easterly trade wind flow,
elsewhere, from 18N southward from 80W eastward.

The wind speeds and the sea heights will diminish across the 
region, gradually, through Friday, as high pressure in the central
Atlantic Ocean shifts eastward. Fresh trade winds and moderate 
easterly swell are expected in the Tropical N Atlantic Ocean 
through the weekend.

ATLANTIC OCEAN... 

An upper level trough starts in the Atlantic Ocean, near 24N55W,
and it continues to 20N61W, into the NE Caribbean Sea, to 18N64W,
and to 15N66W. A surface trough is along 61W/62W from 22N to 30N.
Precipitation: Widely scattered moderate to isolated strong from
17N to 27N between 55W and 63W. Isolated moderate is elsewhere
from 25N northward between 20W and 50W. A shear line is along 
33N30W 30N40W 28N54W. Scatterometer winds from 12 hours ago were 
showing wind speeds ranging from 25 knots to 30 knots on the
northern side of the shear line, and wind speeds ranging from 15
knots to 20 knots on the southern side of the shear line.

The current Gulf of Mexico cold front will move off the southeast
U.S.A. coast later today. The front will stall from 30N70W to 
central Florida on Thursday. The cold front will transition into 
a warm front on Friday. Fresh to strong NE winds and building 
seas are expected to the north of the front, from tonight through
Thursday night.

$$
MT