000 AXNT20 KNHC 201738 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 PM EST TUE DEC 20 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 1715 UTC. ...THE ITCZ/THE MONSOON TROUGH... The Monsoon Trough reaches the coastal sections of Liberia near 05N09W to 04N13W. The ITCZ continues from 04N13W to 01N27W 03N39W and 02N42W. Convective precipitation: scattered moderate to strong from 01N to 05N between 30W and 38W. widely scattered moderate to isolated strong from 02N southward between 18W and 21W, from 03N to 04N between 23W and 25W, from 08N to 11N between 39W and 45W, and from 08N to 10N between 54W and 57W. High level clouds are to the south of the line that passes through 26N16W 20N30W 17N50W 16N60W. The high level clouds are moving northeastward. ...DISCUSSION... ...FROM THE WESTERN ATLANTIC OCEAN INTO THE GULF OF MEXICO, AND THE REST OF THE GULF OF MEXICO... The gale warning for the Gulf of Mexico ended a few hours ago. Please read the Atlantic high seas forecast, that is listed under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC, for more details about any residual wind conditions. Upper level W-to-NW wind flow spans the entire Gulf of Mexico. This wind regime is part of larger-scale anticyclonic wind flow that spans Mexico and the Gulf of Mexico. An upper level trough passes through 33N72W to 28N76W. A stationary front extends from a 1024 mb low pressure center that is near 33N75W, to 30N76W, curving to 27N80W, across Florida to 27N85W in the eastern Gulf of Mexico. The front becomes stationary near 27N85W, and it continues to 25N90W 23N93W and 17N93W in the Isthmus of Tehuantepec. Convective precipitation: isolated moderate from 22N to 23N between 94W and 95W, and from 20N to 21N between 93W and 95W. Rainshowers are possible also to the north and west of the cold front/ stationary front. in the Atlantic Ocean: isolated moderate to the NW of the line that passes through 32N70W 27N80W. Surface high pressure passes through the deep south of Texas, through the coastal plains of Mexico, between the coast and 100W, toward the Isthmus of Tehuantepec of southern Mexico. Storm-force winds are blowing in the Gulf of Tehuantepec on the eastern Pacific Ocean side of southern Mexico. Please read the Eastern Pacific Ocean HIGH SEAS FORECAST...MIAHSFEP2/FZPN03 KNHC...and the Eastern Pacific Ocean TROPICAL WEATHER DISCUSSION...MIATWDEP/AXPZ20 KNHC...for more details. ...LOW LEVEL CLOUD CEILINGS AND WEATHER FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD... LIFR: KMIS and KDLP. IFR: KGRY, KSPR, KIKT, KVOA, and KVKY. MVFR: KHHV, KVAF, KEMK, KGUL, KHQI, KGBK, KEHC, KVQT, KGHB, KATP, KEIR, and KMDJ. LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA... TEXAS: VFR. LOUISIANA: IFR/LIFR from the areas that are around Lake Pontchartrain southeastward to the coast. MISSISSIPPI: LIFR in the southernmost coastal sections of the state. LIFR/IFR in the Hattiesburg metropolitan area. ALABAMA: LIFR in the southernmost coastal sections of the state. FLORIDA: LIFR/IFR from Cross City westward. IFR at the Tampa Executive Airport and at the St. Pete/Clearwater International Airport. IFR in Sarasota. MVFR in parts of the Ft. Myers metropolitan area. ...THE CARIBBEAN SEA... An upper level trough passes through 20N63W, to 15N70W, to 11N79W, from NE to SW, across the Caribbean Sea. Convective precipitation: isolated moderate within 250 nm on either side of 16N50W 15N70W 13N80W 10N84W. Upper level NE wind flow covers the area that is on the northern side of the trough, and definitely from 80W westward. Upper level SW wind flow covers the area that is on the southern side of the trough, and from 70W eastward. 24-HOUR rainfall totals in inches for the period ending at 20/1200 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 0.51 in St. Thomas in the U.S.A. Virgin Islands, 0.22 in San Juan in Puerto Rico, 0.06 in Guadeloupe and Curacao, and 0.05 in Montego Bay in Jamaica. ...HISPANIOLA... Upper level NE wind flow is moving across Hispaniola. Convective precipitation: Rainshowers are possible across Hispaniola, and in the coastal waters and coastal plains, in areas of broken low level to middle level clouds. SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: VFR/no ceiling. for the DOMINICAN REPUBLIC: Barahona: VFR/no ceiling. few cumulonimbus clouds. Santo Domingo: VFR/no ceiling. La Romana: earlier rain has ended for the moment. VFR. few cumulonimbus clouds. Punta Cana: earlier rain has ended for the moment. VFR/no ceiling. Santiago: MVFR. ceiling 1600 feet. Puerto Plata: MVFR. ceiling 1800 feet. The GFS MODEL forecast for 250 MB shows that NE wind flow will move across the area for the first 24 hours of the 48-hour forecast period. The trough moves northward, across Puerto Rico and northeastward out of the Caribbean Sea. A second trough moves from Florida to SE Cuba. Expect the wind flow during day two to be from the N, to the NW, and finally from the SW as the trough becomes closer to Hispaniola. The GFS MODEL forecast for 500 MB shows that NE wind flow will move across the area, with an Atlantic Ocean-to-Puerto Rico trough. The GFS MODEL forecast for 700 mb shows that NE wind flow will move across the area. It is possible that an inverted trough will move across Hispaniola during each day of the 48-hour forecast period. ...THE REST OF THE ATLANTIC OCEAN... An upper level trough extends from a 32N20W cyclonic circulation center, to 28N28W 27N40W 25N52W beyond 20N63W, and into the Caribbean Sea. Convective precipitation: widely scattered moderate to isolated strong from 22N to 26N between 43W and 51W. Rainshowers are possible elsewhere within 360 nm on either side of the trough. A surface ridge passes through 35N50W to 33N61W, across Bermuda, to 29N72W, and to the NW Bahamas. For additional information please visit http://www.hurricanes.gov/marine $$ MT