000
AXNT20 KNHC 210004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
704 PM EST Wed Dec 20 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 1800 UTC surface analysis and satellite imagery through 
2345 UTC.

...ITCZ/MONSOON TROUGH... 

The monsoon trough enters the Atlantic Ocean from 07N13W to 
06N18W to 04N24W. The ITCZ extends from 04N24W to 03N40W to 01N50W.
Scattered moderate convection is from 02N-06N between 02W-20W
and from 0N-08N between 20W-40W.

...DISCUSSION...

...GULF OF MEXICO...

A stationary front extends from Mississippi SW to 26N93W to 23N97W
with possible isolated showers within 60 nm either side of the
boundary. This front is expected to retreat toward the northeast 
Gulf coast while weakening tonight. A surface trough is ahead of
the front in the SW Gulf, which extends from 23N95W to the Bay of
Campeche near 18N95W. With shallow moisture in this region of the
basin, isolated showers are possible within 60 nm either side of
the trough axis. Otherwise, surface high pressure anchored by a
1019 mb high in the SW N Atlc extends a ridge axis across the
Florida peninsula and the Gulf to near 94W. Light to gentle
variable winds dominate the basin, except for N of 28N E of 90W
where moderate to fresh SW winds are observed. The next cold 
front is forecast to come off the coast of Texas early Saturday
morning, extend from the Florida Big Bend SW to Tampico, Mexico
Sunday near sunrise and from south Florida to Veracruz, Mexico
Monday morning. Fresh to near gale force northerly winds will
follow the front starting Saturday.

...CARIBBEAN SEA...

Broad middle to upper level ridging dominates the Caribbean waters
along with very dry air aloft, which is supporting fair weather. Scatterometer
data indicates that strong to near gale winds are present over 
the southwest Caribbean from 10N-13N between 73W-78W. A surface
ridge anchored over the SW N Atlc waters continue to tighten the
pressure gradient over the central Caribbean, thus resulting in
fresh to strong winds between 68W and 80W and near gale-force
winds along the coast of Colombia. Little change is expected in 
the upper-to mid-level pattern through Friday and these conditions
will persist through that time.

...HISPANIOLA...

As previously discussed, broad mid to upper-level anticyclonic 
wind flow and dry upper-to mid-level air dominate the entire 
Caribbean Sea supporting mostly stable conditions. However, low- 
topped trade wind showers are forecast for the NE Dominican
Republic Friday and Saturday evenings. 

...ATLANTIC OCEAN...

With little support aloft, a weak cold front extending from 31N54W
SW to 27N63W is forecast to dissipate by Thursday evening. The
remainder SW N Atlc is dominated by a surface ridge anchored by a
1019 mb high near 26N72W. In the north-central Atlc, the remnants
of a stationary front are analyzed as a surface trough from 30N38W
to 26N44W to 24N52W. This boundary is under a diffluent
environment aloft, which is supporting scattered heavy showers N
of 25N between 35W and 46W. Otherwise, the subtropical high 
dominates the northeast Atlantic waters. A cold front associated 
with a surface low currently in South Carolina will enter the NW
waters Thu morning and race SE over the SW N Atlc waters through
Friday night. A stronger cold front will enter this same region
Sunday night.

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

$$
Ramos