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AXNT20 KNHC 211034
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
533 AM EST Tue Nov 21 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 0600 UTC surface analysis and satellite imagery through 0945 UTC.


...SPECIAL FEATURES... Cyclogenesis is expected to occur late Wednesday into Wednesday night across portions of the Gulf of Mexico producing near gale to gale force northerly winds S of 22N W of 93W. The gale force wind field is expected to persist through late Wednesday night... diminishing into strong to near gale force strength by Thursday morning across portions of the SW Gulf of Mexico. 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 11N16W to 09N19W. The Intertropical Convergence Zone axis extends from 09N19W to 08N33W to 06N42W to 05N52W. Scattered moderate convection is from 02N-11N between 08W-37W.


...DISCUSSION...

GULF OF MEXICO... A middle to upper level trough is noted on water vapor imagery over the western Gulf with axis extending from 31N91W to a base over the SW Gulf waters near 21N94W. The trough supports a surface trough extending from 28N86W to 24N87W to 22N93W to 20N95W. Scattered showers and isolated tstms are occurring within 90 nm either side of the boundary. Otherwise...generally gentle to moderate E-SE winds prevail across the basin this morning on the southwestern periphery of a surface ridge anchored by a 1027 mb high centered offshore of the Carolinas near 36N73W. The troughing moving over the basin will strengthen the current surface troughing across the eastern waters and a frontal wave across the western waters through early Wednesday with fresh to strong northerly winds expected to materialize by Wednesday afternoon into the evening. Global models indicate cyclogenesis across central and eastern portions of the basin Wednesday night.

CARIBBEAN SEA... Southwesterly flow aloft prevails over the western Caribbean with a ribbon of mid-level energy stretching from over the Windward Passage region W-SW to over portions of Central America in the vicinity of Honduras and El Salvador. This mid-level energy is supporting a surface trough analyzed from 12N78W to 19N75W. Widely scattered showers and isolated tstms are occurring N of 15N between 70W-80W. A portion of this activity extends N of the Windward Passage region in the Atlc waters. Otherwise...moderate trades are noted E of 77W and moderate to occasional fresh NE winds are occurring W of 77W. This pattern is forecast to persist through Thursday night.


...HISPANIOLA... A surface trough lies to the SW of the island with widely scattered showers and isolated tstms occurring generally W of the island this morning across the Windward Passage region. The surface troughing will be slow to move and dissipate through Wednesday...so little change is expected through mid-week.

ATLANTIC OCEAN... A cold front extends into the discussion area near 32N55W and continues SW to 29N61W becoming stationary to the NW Bahamas and offshore waters of southern Florida. Isolated showers are occurring within 60 nm either side of the front. To the N of the front...surface ridging prevails anchored by a 1027 mb high centered offshore of the Carolinas near 36N73W. SE of the front...mid-level shortwave troughing is in the vicinity of 24N66W and supports a surface trough analyzed from 22N68W to 28N62W. Scattered showers and isolated tstms are occurring from 20N-28N between 57W-70W...and from 20N-23N between 70W-77W. Farther east...another middle to upper level trough is noted in the vicinity of 25N39W supporting a 1012 mb low centered near 24N38W with the associated stationary front extending SW from the low to 19N50W to 22N61W. Scattered showers and isolated tstms are occurring within 75 nm either side of the front. This low links up with a 1007 mb low centered near 32N27W by way of a cold front extending from 32N27W to 24N34W then stationary into the 1012 mb low. Scattered showers and isolated tstms are occurring generally N of 25N between 16W-37W.

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

$$ HUFFMAN

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