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Atlantic Tropical Weather Discussion (Text)



000
AXNT20 KNHC 151747
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1247 PM EST Fri Dec 15 2017

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 
1715 UTC.

...SPECIAL FEATURES...

...Gale Warning in the Gulf of Mexico...

A cold front is along 30N84W 27N92W 24N97W. Gale-force NW-to-N
winds, and sea heights ranging from 10 feet to 14 feet, are
forecast during the next 6 hours or so, from 22N to 24N to the
west of the cold front. The gale-force winds are expected for the
next 24 hours. Please read the latest NHC High Seas Forecast 
under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...Gale Warning in the Caribbean Sea...

Strong high pressure will build to the north of the Caribbean Sea 
during the evening today. A tight pressure gradient will develop in
the south central basin. The trade winds will increase to fresh-
to-strong. A strong pressure gradient will persist during the 
weekend. Gale-force winds will be along the northwest of the 
Colombian coast starting tonight through early Monday. The sea
heights will build to 13 feet in this area. Please read the 
latest NHC High Seas Forecast under AWIPS/WMO headers 
MIAHSFAT2/FZNT02 KNHC for more details. 

...ITCZ/MONSOON TROUGH...

The monsoon trough passes through the coastal sections of Liberia
near 07N11W to 06N15W. The ITCZ continues from 06N15W to 04N26W
05N31W and 04N41W. Precipitation: widely scattered moderate to
isolated strong rainshowers are 240 nm to the south of the Monsoon
Trough/ITCZ between 11W and 17W, and within 180 nm to the south of
the ITCZ between 28W and 36W. Scattered moderate to strong is
within 60 nm to 120 nm to the north of the ITCZ between 21W and
26W. widely scattered moderate to isolated strong is elsewhere
within 240 nm to the north of the ITCZ between 19W and 38W.
Scattered moderate to isolated strong rainshowers are from 03N
southward from 47W westward.

...DISCUSSION...

THE GULF OF MEXICO...

Upper level SW wind flow moves from the eastern Pacific ocean,
across the western coast of Mexico near 21N105W, and across the NW
half of the Gulf of Mexico. An upper level ridge extends from N
Colombia, across Central America, to El Salvador, to 15N99W in the
eastern Pacific Ocean. More upper level SW wind flow is reaching
and moving across the Gulf of Mexico, from the anticyclonic wind
flow of the ridge. Comparatively drier air in subsidence covers
the SE half of the Gulf waters. 

A shallow cold front stretches from the Florida Big Bend, into the
N central Gulf of Mexico, into NE Mexico near 24N98W. MVFR/VFR
conditions and areas of light rain are along and to the north of
the cold front. Please refer to the SPECIAL FEATURES section for
more details about the gale-force winds, and seas, that are
related to the cold front.

THE CARIBBEAN SEA...

Middle level-to-upper level anticyclonic wind flow spans the
entire area. An upper level ridge extends from N Colombia, across
Central America, to El Salvador, to 15N99W in the eastern Pacific
Ocean. Comparatively drier air in subsidence also is present
everywhere. 

A surface trough is in the coastal waters of Central America along
82W/83W from 09N to 18N. Scattered to broken low level clouds and
areas of light rain/drizzle are inland from Panama to Costa Rica
to Nicaragua and Honduras. 

The southernmost end of a surface trough, that originates in the
Atlantic Ocean, reaches SE Cuba, and to 20N81W in the Caribbean
Sea. Rainshowers are possible within 60 nm on either side of the
trough. 

Please refer to the SPECIAL FEATURES section for more details
about the development of gale-force winds to the NW of the 
Colombian coast starting tonight through early Monday. 

...HISPANIOLA...

A middle level-to-upper level east-to-west oriented ridge cuts
across the island. 

SURFACE OBSERVATIONS...HAITI, in Port-au-Prince: VFR. in the 
DOMINICAN REPUBLIC: VFR.

The GFS MODEL forecast for 250 mb shows that NW wind flow will
move across the area during the next 48 hours, being on the
eastern side of a ridge. The GFS MODEL forecast for 500 mb shows 
that NE wind flow will move across the area during the next 2 
days, with an anticyclonic circulation center that will be between
the Bahamas and Cuba. The GFS MODEL forecast for 700 mb shows 
that NE-to-E wind flow will move across the area, with an E-to-W
Atlantic Ocean ridge.

THE ATLANTIC OCEAN...

A surface trough passes through 32N52W, to 25N60W, toward the SE
Bahamas/the Turks and Caicos Islands, across SE Cuba, to 20N81W,
in the Caribbean Sea. Rainshowers are possible within 30 nm on
either side of the trough. The southernmost point of an upper
level trough reaches 32N55W. Upper level anticyclonic wind flow is
moving across the area of the surface trough.

An upper level trough extends from an 18N33W cyclonic circulation
center, to 12N40W 08N51W, to the coast of Guyana near 07N58W. No
deep convective precipitation is associated with this feature. 

A surface trough is along 43W/44W from 20N to 25N. Rainshowers are
possible within 240 nm on either side of the trough. Isolated
moderate rainshowers already are within 400 nm to the SE of the
surface trough, moving westward with a separate area of low level
clouds.

Upper level cyclonic wind flow, with a trough, covers the area
that is from 22N northward between Africa and 24W. Surface
anticyclonic wind flow is present in the same area. A surface
ridge extends from a 1033 mb high pressure center that is near
36N29W to the Canary Islands, into northern Mauritania.

The current Gulf of Mexico cold front will move off the northeast
Florida coast this evening, reach from Bermuda to south Florida 
Saturday, and then will stall and gradually dissipate along 25N 
through early next week. High pressure from the southeast United 
States will build eastward across the area behind the front.

For additional information please visit 
http://www.hurricanes.gov/marine

$$
MT

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Page last modified: Friday, 15-Dec-2017 17:48:13 UTC