000 AXNT20 KNHC 052350 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 700 PM EST Tue Dec 5 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 2315 UTC. ...SPECIAL FEATURES... ...GALE-FORCE WINDS IN THE GULF OF MEXICO... A cold front currently extending from the Ohio Valley through the deep south and extending from near Lake Charles, Louisiana to near Corpus Christi, Texas is forecast to sweep further into the Gulf of Mexico as strong high pressure building behind the front will tighten the pressure gradient in the western Gulf, thus supporting gale force winds beginning tonight over the northwest Gulf then spreading southward to the southwest Gulf by late Thursday. Seas will build to 10 to 13 FT by Thursday. Please read the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 for more details. ...GALE-FORCE WINDS IN THE ATLANTIC... Strong low pressure well N of the forecast waters with associated cold front extending from 31N45W to 28N50W to 27N62W. Earlier scatterometer data indicated W to NW winds of 30 to 35 KT N of 29N west of the front to 54W. Seas of 17 to 24 Ft were noted in the area. The front will continue to drift ESE during the next 24 hours when the winds are expected to decrease below gale force. Please read the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 08N13W then immediately transitions to the Intertropical Convergence Zone near 07N16W then continues through 05N30W to 04N47W to 07N57W. Scattered moderate convection is within 90 nm of the ITCZ W of 23W. ...DISCUSSION... GULF OF MEXICO... A strong cold front has emerged off the Gulf coast and extends from Lake Charles, Louisiana to Corpus Christi, Texas as of 2100 UTC. Light to locally moderate return flow was noted in advance of the front over the remainder of the Gulf N of 25N. Mosaic radar imagery indicated scattered showers and thunderstorms along and to the north of the front from southern Mississippi, Louisiana to the middle and upper Texas coastal waters. Generally fair conditions prevail elsewhere over the basin within a ridge of high pressure along 26N. Strong high pressure building behind the front will tighten the pressure gradient in the NW Gulf and will support frequent gust to gale force winds beginning tonight. Scattered showers and thunderstorms will be associated with this front as it moves across the basin. Heavy showers are expected in the SE Gulf Friday into Saturday as the front moves further SE. Please see the special features section above for information on the Gale force winds. CARIBBEAN SEA... Deep tropical moisture over the SW Caribbean is interacting with diffluent flow aloft to support clusters of moderate to strong convection generally S of 13N and W of 79W. East of this area of convection a 1007 mb surface low was embedded in the eastern extension of the EPAC monsoon trough. A surface trough over the eastern Caribbean extends from 19N64W to 11N66W and supports scattered showers and isolated thunderstorms over Puerto Rico, the Virgin Islands and the Lesser Antilles.The remainder of the Caribbean is generally void of convection. High pressure north of the region supports fresh to locally strong trades over the Central Caribbean gnerally between 70W and 82W, and moderate trades elsewhere. Little change is expected over the next 48 hours. HISPANIOLA... Increasing deep layered moisture from the southwest Caribbean is advecting over Hispaniola. This was reflected in the 1200 UTC rawinsonde from Santo Domingo which indicated mositure to about 560 millibars and TPW values of 1.8 inches. Currently mulit- layered clouds with scattered showers are occurring over the island. Additional moisture from a surface trough over the eastern Caribbean will support scattered showers Wed through Fri. ATLANTIC OCEAN... Strong high pressure anchored over the NW Atlc waters extends a ridge axis SSW covering the SW N Atlc waters generally W of 62W. In the central Atlc, a middle to upper level low with associated trough continue to support a cold front extending from 30N49W SW to 27N56W to 27N64W. Gale force winds are W of this front N of 30N. See special features section for further details. A middle level low near 47N32W supports another frontal system analyzed as a stationary front along 30N32W SW to 23N50W to 21N63W. Scattered showers and isolated tstms are within 120 nm either side of the boundary. This front is forecast to dissipate within the next 24 hours. High pressure centered over Spain extends SW and covers the remainder of the eastern Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ Cobb