Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 180003

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
703 PM EST Sat Feb 17 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 1800 UTC surface analysis and satellite imagery through 
2345 UTC. 


Caribbean Sea Gale Warning: A tight surface pressure gradient,
that exists between surface high pressure in the western Atlantic
Ocean, and lower surface pressure in northern sections of South 
America, should continue to support winds pulsing to minimal 
gale-force near the coast of Colombia through early next week. 
The resultant wave heights with the gale force NE to E winds are 
forecast to range from 12 to 16 feet, building to 12 to 18 ft Mon.
Please read the latest NHC High Seas Forecast under AWIPS/WMO 
headers MIAHSFAT2/FZNT02 KNHC for more details.


The monsoon trough axis extends from the southern coastal 
sections of Liberia near 05N08W southwestward to 03N14W and 
dips to 01N18W, where it dips to below the Equator as the ITCZ
axis to 02S28W and to the coast of Brazil near 04S38W. Numerous
strong convection is well S of the coast of Africa and monsoon 
trough from 01S to 04N between the prime meridian and 05W.
Scattered moderate convection is within 30 nm of line from 01N27W
to 01N31W to 02N35W.



A surface ridge extends from an Atlantic Ocean 1026 mb high
pressure center located near 27N66W, to central Florida, to 
26N90W in the Gulf of Mexico, to the western gulf near 25N95W.
The ridge will continue to maintain mainly gentle to moderate 
southeast winds in the western Gulf, and light to gentle east to 
southeast elsewhere through Sun night with the exception of 
moderate winds in the SE waters and the Straits of Florida. Areas
of dense fog producing reduced visibility to below 1 nm are again
expected to form tonight mainly N of 27N and persist into Sun
afternoon in some locations. Isolated showers are over some
portions of the eastern gulf and far SE waters near the Straits of
Florida. Expect increasing winds and building seas by early next 
week as high pressure strengthens in the western Atlantic Ocean. A
thermal trough will develop in the western Yucatan Peninsula 
during each afternoon. The trough will drift westward across the 
eastern Bay of Campeche during the overnight hours, and then 
dissipate in the SW Gulf waters by late each morning.


Please read the SPECIAL FEATURES section for details regarding 
the Gale Warning near the coast of Colombia. 

Patches of broken to at times overcast low clouds with isolated 
showers are quickly moving westward across the western and central
Caribbean N of about 14N, and also over portions of the eastern 

A tight pressure gradient between a high pressure system that is 
in the western Atlantic Ocean, and lower pressure in northern 
sections of South America, will continue to support pulsing winds 
of minimal gale force near the coast of Colombia through early 
next week. Fresh to locally strong trade winds are expected 
elsewhere across the Caribbean Sea. The high pressure will be 
reinforced by a stronger high pressure system on Mon. The stronger
system will bring increasing winds and building seas across the 
eastern and central Caribbean Sea, and the Tropical N Atlantic 
waters possibly into the middle of next week.


An upper level trough extends from a 25N45W cyclonic circulation 
center, to 17N50W, to 13N61W in the SE Caribbean Sea. A surface 
trough extends from 31N50W to 26N59W, and another one extends 
from near 31N45W to 24N45W 26N47W. A second surface trough is 
along 45W from 24N to 31N. Isolated showers and thunderstorms 
are noted near the second trough from 20N to 26N between 40W and 

Broad surface anticyclonic wind flow covers the Atlantic Ocean
to the N of 17N and to the W of 50W. A 1026 mb high pressure 
center is near 27N66W.

An E to W ridge along 27N, will shift gradually N to be along 28N
tonight, and then retract eastward, allowing a weak cold front to
move off the southeast United States on Sun. The front will stall
quickly and dissipate across the NW waters on Mon. Gentle to  
moderate winds will prevail north of the ridge, with moderate  
to fresh winds expected generally south of 25N, except becoming 
strong along the north coast of Hispaniola and the northern 
approach to the Windward Passage each evening. The ridge will be 
reinforced by a stronger high pressure system on Monday.

For additional information please visit 


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Page last modified: Sunday, 18-Feb-2018 00:03:41 UTC