000 AXNT20 KNHC 212340 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 640 PM 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... A broad area of low pressure is developing over the northern Gulf of Mexico while high pressure builds over the central US. The pressure gradient between these two features will produce near gale to gale-force northerly winds south of 21N and west of 95W. The gale force wind field is expected to persist until mid Thursday morning, diminishing into strong to near gale force strength by the afternoon hours 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. A 1004 mb low centered near 32N22W is producing gale force winds across the Meteo-France forecast area of Irving as confirmed by scatterometer data. These winds are forecast to diminish below gale force by tonight. Please refer to the Meteo-France forecast found at www.meteofrance.com/previsions-meteo-marine/bulletin/ grandlarge/metarea2 for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N14W to 07N20W. The Intertropical Convergence Zone extends from 07N20W to the South America Coast near 06N57W. Scattered moderate convection is within 200 nm on either side of the boundaries mainly east of 30W. Scattered showers prevail over the remainder of the ITCZ. ...DISCUSSION... GULF OF MEXICO... An upper-level trough over the central Gulf of Mexico is supporting a 1013 mb surface low near 29N86W. A surface trough extends from the low to 25N87W, while a warm front is from the low to 29N82W. This system is supporting clusters of moderate noted over the northern half of the basin. Please refer tot he section above about the Gale Warning, which is expected to develop during the next 12-18 hours. A surface trough extends over the Bay of Campeche 23N94W to 20N97W. During the next 24 hours the low over the northeast Gulf will cross north Florida. Another piece of energy at the mid to upper levels will enter the northwest Gulf which will develop another low over this area. A cold front will accompany this low enhancing winds/seas. CARIBBEAN SEA... A surface trough extends over the western Caribbean from 16N80W to 11N81W supporting scattered showers mainly west of 80W. Mainly gentle to moderate winds cover the western Caribbean, while moderate easterly winds cover the eastern Caribbean. Expect during the next 24 hours for the trough to move west with convection. ...HISPANIOLA... Deep moisture in mid to upper level southwest flow continues to support showers and isolated thunderstorms over the island. This pattern will likely continue through tonight, with a possible drying trend expected by late Wednesday as a mid to upper level ridge builds over the area. ATLANTIC OCEAN... A frontal system extends across the west-central Atlantic, analyzed as a cold front from 31N50W to 27N62W, then as a stationary front from that point to 28N72W, ending as a warm front from 28N72W to 29N81W. Scattered moderate convection prevails in the vicinity of the boundary mainly west of 70W. Fresh to strong winds are noted from 27N-30N between 62W-77W. To the east, a 1012 mb surface low is centered near 23N39W. A stationary frontal boundary extends from the low to 17N53W then weakens through 20N61W. Another stationary front extends northeast from the low to 25N30W. Scattered showers are noted along the frontal boundaries. Fresh to strong winds are noted from 21N-25N between 37W-52W. A 1004 mb low north of the area extends its cold front from 30N22W to 25N29W. Gale force winds prevail over the southern semicircle of the low. Refer to the section above for more details. For additional information please visit http://www.hurricanes.gov/marine $$ ERA