000 AXNT20 KNHC 161804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 104 PM EST Sat Dec 16 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...SPECIAL FEATURES... ...Gale Warning in the Caribbean Sea... Strong surface high pressure that is in the SW N Atlantic Ocean is helping to create a strong surface pressure gradient in the Caribbean Sea. Expect NE-to-E gale-force winds, at times, along the coast of Colombia from 11N to 13N between 73W and 77W with minor variations, during the next two days. The gale-force winds will pulse at night, continuing through Monday. The sea heights will range from 10 feet to 15 feet in this same area. Please read the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough passes through the coastal sections of Sierra Leone near 07N11W, to 06N15W. The ITCZ continues from 06N15W to 05N29W and 02N36W, and to 01N40W. Precipitation: from 10N southward between 06W and 34W. widely scattered moderate to isolated strong rainshowers from 10N southward between 06W and 34W. isolated moderate from 06N southward between 34W and 53W. An upper level trough passes through Africa near 30N03W, to the Atlantic Ocean near 25N23W, to 18N31W 15N40W 10N43W, and to 08N53W. No significant deep convective precipitation is apparent in satellite imagery. A surface trough is along 51W/52W from 12N to 23N. rainshowers are possible from 10N to 24N between 43W and 60W. ...DISCUSSION... THE GULF OF MEXICO... A stationary front extends from the area of Tampa Florida, toward the central Gulf of Mexico, curving southward to the northern part of the Isthmus of Tehuantepec of southern Mexico. A surface trough has formed along the coast of the Deep South of Texas and extreme NE Mexico. A surface low pressure center is forecast to form in the area of the current surface trough, and move to the coastal areas of SW Louisiana in 24 hours. The stationary front will transition into a warm front and move northward, into the NW corner of the Gulf of Mexico. It is possible that the warm front may connect with the surface low pressure center that is forecast to develop. Broken to overcast low level, and some areas of rainshowers, cover the Gulf waters, to the north and NW of 86W from 21N to 27N. THE CARIBBEAN SEA... A middle level-to-upper level ridge extends from the NE corner of the Caribbean Sea, toward Jamaica, through the Yucatan Channel. Colombia to the NW part of Cuba. A surface trough extends from southern Honduras to 20N along the coast of the Yucatan Peninsula of Mexico, in the NW corner of the Caribbean Sea. Broken low level clouds and possible rainshowers cover the area from Nicaragua to Honduras, to Belize, to the NE corner of the Yucatan Peninsula. Please refer to the SPECIAL FEATURES section for more details about the gale-force winds for the coast of Colombia during the next two days. ...HISPANIOLA... Upper level NW wind flow is moving across Hispaniola. Broad middle level-to-upper level anticyclonic wind flow spans the entire Caribbean Sea. SURFACE OBSERVATIONS...HAITI, in Port-au-Prince: VFR. in the DOMINICAN REPUBLIC: VFR at all the locations. The GFS MODEL forecast for 250 mb shows that a ridge will be to the west of Hispaniola. Expect NW wind flow during the next 48 hours. The GFS MODEL forecast for 500 mb shows that NE wind flow will move across the area during the next 2 days, with an Atlantic Bahamas-to-SE Cuba anticyclonic circulation center. The GFS MODEL forecast for 700 mb shows that NE wind flow will move across the area, with an Atlantic Ocean-to-Florida ridge. THE ATLANTIC OCEAN... A deep layer trough passes through 32N42W to 26N44W. rainshowers are possible from 24N to 30N between 45W and 50W. A shallow cold front passes through Bermuda, to 30N71W, and to central Florida. A surface trough also is along 30N66W to 26N72W, to Andros Island in the Bahamas. Broken to overcast low level clouds and possible rainshowers are to the west of the line that passes through 32N50W 24N66W 21N76W. An upper level trough passes through Africa near 30N03W, to the Atlantic Ocean near 25N23W, to 18N31W 15N40W 10N43W, and to 08N53W. No significant deep convective precipitation is apparent in satellite imagery. A surface trough is along 51W/52W from 12N to 23N. rainshowers are possible from 10N to 24N between 43W and 60W. For additional information please visit http://www.hurricanes.gov/marine $$ MT