000 AXNT20 KNHC 271727 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1227 PM EST TUE DEC 27 2016 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 1200 UTC surface analysis and satellite imagery through 1700 UTC. ...SPECIAL FEATURE... Please refer to the METEO-FRANCE High Seas Forecast, that is listed under the following links: MARINE...BULLETINS EXPERTISES...GRAND LARGE...METAREA II...or on the website: WWW.METEOFRANCE.COM/PREVISIONS-METEO-MARINE/BULLETIN/ GRANDLARGE/METAREA2. Gale-force winds are forecast for the area that is called: IRVING. The OUTLOOK, for the 24 hours that follow the forecast that is valid until 28/1200 UTC, consists of: the persistence of a cyclonic gale or near gale in IRVING. ...THE ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the coast of Liberia near 06N10W to 05N15W. The monsoon trough continues from 05N15W to 01N28W to 02N39W, then resumes from 08N45W to 07N56W. Scattered moderate and isolated strong convection is present from 01N to 04N between 02W and 15W and from 00N to 06N between 25W and 35W. A surface trough extends from 06N43W to 10N39W. Scattered moderate convection is seen from 07N to 12N between 43W and 52W. ...DISCUSSION... ...GULF OF MEXICO... A broad upper-level ridge covers the western Gulf. A broad upper- level trough extends southwestward from the Florida big bend to the Yucatan peninsula. Convergent upper-level winds between these two features is generally suppressing convection over the Gulf, except near the ridge axis over the Bay of Campeche. A weak surface ridge extends westward along the northern gulf coast. A surface trough reaches northward from the Isthmus of Tehuantepec at 18N95W into the Bay of Campeche at 22N93W. Scattered moderate and isolated strong convection associated with the trough is found from 19N to 22N between 95W and 97W. Gentle to moderate east winds are generally observed across the Gulf of Mexico. This easterly flow will weaken tonight and Wednesday as the surface ridge shifts southward in advance of the next cold front. Warm, moist, air will support patchy fog over the northwest Gulf until the cold front arrives. The cold front is expected to enter the Gulf around midday on Thursday. ...CARIBBEAN SEA... An upper-level ridge extends NW from Colombia over the western Caribbean to eastern Cuba. A broad upper-level trough heads northeastward from Venezuela over the Virgin Islands. Convergent upper-level flow between these two features is suppressing deep convection. This weather pattern is expected to continue for the next several days. The west Atlantic surface ridge continues to give the Caribbean fresh to strong northeast winds. Surface low pressure and an attendant cold front moving eastward from the east coast of the United states will weaken the ridge, which will allow wind speeds over all of the Caribbean except north of the coast of Colombia to decrease to between moderate and fresh by Thursday night. ...HISPANIOLA... A relatively dry weather pattern will remain in place for the next few days as convergent upper-level winds to the west of an upper- level trough stay overhead. Fresh to strong trades will decrease by Friday as the ridge to the north weakens. ...ATLANTIC OCEAN... A weak upper-level trough is moving eastward from the Florida peninsula. A much larger upper-level trough extends eastward from the Virgin Islands to the Azores. The cold front associated with the larger upper-level trough curves southwestward from 31N36W to 24N49W. The boundary continues as a weakening front to 24N56W. A surface ridge covering the central Atlantic is anchored by 1031 mb high pressure centered near 34N57W. A weakening surface trough lingers along the Florida east coast from 25N81W to 31N81W. Scattered showers are located within 30 nm of the trough axis to the north of 27N. The Atlantic surface ridge will gradually shift eastward in advance of a cold front that will move off the southeastern United States on Wednesday. This will weaken winds to the west of 60W. A much stronger cold front will blast southeastward from the United States mainland on Thursday night and continue into the Bahamas on Friday. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy