AXNT20 KNHC 110503

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1203 AM EST Mon Dec 11 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 0000 UTC surface analysis and satellite imagery through 0415 UTC.

...SPECIAL FEATURES... A cold front extends across the SW North Atlc waters from 32N64W SW to the Windward Passage and then to the SW Caribbean Sea near 11N79W. Strong high pressure continues to build in W of the front across Cuba...the NW Caribbean Sea...and much of Central America this evening resulting in near gale to gale force N winds generally S of 18N W of the front to 83W off the coast of Nicaragua. As the front creeps eastward and eventually begins to stall by Monday morning...the remaining boundary will extend from the Windward Passage region to the coast of Costa Rica with fresh to strong N winds continuing to diminish gradually through mid- week. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 06N11W to 05N22W. The Intertropical Convergence Zone axis extends from 05N22W to 03N32W to 06N41W. No significant deep convection noted on satellite imagery at this time.


GULF OF MEXICO... A surface ridge extends across the entire basin anchored by a 1031 mb high centered across northern Mexico near 27N100W. Light to gentle N winds are noted W of 90W...and gentle to moderate N winds are noted E of 90W. The ridging will build in across the northern Gulf through Monday night with generally gentle to moderate anticyclonic winds expected across much of the basin. By Tuesday...the next weak cold front will emerge off the SE CONUS coast introducing a brief period of fresh W-NW winds to the northern water Tuesday morning and eastern waters Tuesday afternoon into the evening. The front will be quick to clear east of the basin with moderate northerly winds prevailing Wednesday into Thursday.

CARIBBEAN SEA... The primary feature across the basin is the cold front extending across the western waters generating the near gale to gale force northerly winds. Scattered showers and tstms are occurring generally S of 18N between 76W-84W...and within 60 nm either side of the cold front N of 18N. Much of this convection is supported aloft by a divergent upper level pattern on the western periphery of an upper level anticyclone anchored over northern Colombia near 11N75W. East of the anticyclonic circulation...dry northerly flow prevails providing overall stability to the central and eastern Caribbean this evening. A few isolated showers are noted on satellite imagery across the NE Caribbean...but remain quick- moving and embedded within gentle to moderate trades. The front is forecast to become stationary across the western Caribbean and begin to gradually weaken through mid-week.

...HISPANIOLA... Fair weather conditions prevail across the island this evening while a cold front remains analyzed across the Windward Passage region. Isolated showers and tstms are possible within 60 nm either side of the front which is expected to stall overnight into Monday and begin a weakening trend through Tuesday night.

ATLANTIC OCEAN... Water vapor imagery indicates a middle to upper level trough over the eastern CONUS and western North Atlc waters supporting the Special Features cold front extending from 32N64W to the Windward Passage and into the SW Caribbean Sea. Isolated showers are occurring within 120 nm either side of the front. Otherwise...the remainder of the SW North Atlc waters are under the influence of a surface ridge anchored over the Gulf of Mexico and portions of NE Mexico. Elsewhere...water vapor imagery indicates a cut-off middle to upper level low centered near 24N48W that continues to slowly retrograde. A surface trough extends from 20N47W to 29N44W providing focus for scattered showers and tstms from 19N-28N between 39W-49W. The trough is forecast to drift westward across the central Atlc through Monday night.

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