Tropical Weather Discussion
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AXNT20 KNHC 211726

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1225 PM EST Sun Jan 21 2018

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.


The African monsoon trough enters the Atlantic Ocean near 04N08W
and continues to 01N22W. The ITCZ begins near 01N22W and extends
to 01N37W to 02N50W. Scattered moderate convection is within 175
nm N of the ITCZ. Isolated showers are within 210 nm S of the ITCZ.



Ridging extends across the SW N Atlantic waters, across the
Florida Peninsula and into the Gulf. Moderate to fresh southeast
return flow is observed over the northwest Gulf between the ridge
and lower pressure over the central Plains. Fresh easterlies are
also noted over portions of the Straits of Florida. Moderate east
to southeast winds persist elsewhere. A mid to upper level short-
wave trough over the SE CONUS extending across the E Gulf along
with the western periphery of a ridge over the Caribbean continue
to support diffluent flow over the NW Caribbean and into portions
of the SE Gulf. This environment aloft along with shallow
moisture is supporting isolated showers in the Florida Straits.
Dense fog continue to be reported in the NW basin N of 25N W of
91W. Caution must be exercised transiting in this area. Moderate
to fresh SE winds will continue across the western Gulf through
tonight ahead of the next cold front to move southeast off the
Texas coast before sunrise on Mon. The cold front will extend
from Dixie, Florida SW to the eastern Bay of Campeche Tue morning,
and from the Straits of Florida to the Yucatan Peninsula
Wednesday morning. Fresh to strong northerly winds will accompany
the passage of the front.


Clusters of showers and thunderstorms are ongoing across the
northwest Caribbean, related to diffluence aloft at the base a
sharp mid to upper trough extending from the SE CONUS into the E
Gulf. Fresh to near gale-force trade winds are noted in latest
scatterometer data over much of the central Caribbean with the
strongest winds being along the coast of Colombia. Seas are 10 to
14 ft over the south central Caribbean with highest seas off
Colombia. Moderate to fresh trades are noted in the eastern
Caribbean and east of the Windward and Leeward Islands. Persistent
ridging north of the area will allow strong to near gale force
trades to pulse along the northwest coast of Colombia through
Friday. The tail of a cold front is forecast to reach the NW
Caribbean waters by late Wednesday night. Fresh to strong
northeasterly winds will populate the NW Caribbean waters through
Friday as the front continues to move SE across the SW N Atlc
waters. Moderate to fresh trades will continue across the tropical
Atlc waters E of the Windwards through Friday.


Ridging covers the SW N Atlc waters being anchored by a 1026 mb
high pressure area centered near 29N62W. Diffluence aloft on the
east side of a mid to upper trough over the E Gulf of Mexico is
supporting isolated showers off the Florida coast and across the
Bahamas to 70W. Former cold front over the central Atlc waters has
stalled along 30N40W to 23N51W to 21N58W where it starts to
dissipate. Latest scatterometer data show fresh trade winds
across the Turks/Caicos and southern Bahamas, along the
dissipating stationary front. Scattered showers are noted N of
23N between 30W and 46W. A 1036 mb high pressure centered over SW
Portugal adjacent waters extends a ridge over the eastern Atlc region
north of 20N. Farther south, moderate to fresh trade persist
across the deep tropics. The High pressure will shift east to just
southwest of Bermuda through Mon, then shift north of Bermuda Mon
night allowing a cold front to move off the northeast Florida
coast Tue afternoon. The cold front will reach from near Bermuda
to Straits of Florida Wed night and from 27N65W to Central Cuba on
Thu night. Strengthening high pres in the wake of the front will
support strong NE wind W of 73W.

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