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000
AXNT20 KNHC 180003
TWDAT

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.


...SPECIAL FEATURES...

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.


...MONSOON TROUGH/ITCZ...

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.


...DISCUSSION...

GULF OF MEXICO...

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.

CARIBBEAN SEA...

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 Caribbean.

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.

ATLANTIC OCEAN...

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 45W.

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 http://www.hurricanes.gov/marine

$$ MT/Aguirre

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