000 AXNT20 KNHC 181804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 PM EST SUN DEC 18 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. ...SPECIAL FEATURES... ..GULF OF MEXICO GALE WARNING... A cold front is along 30N91W 26N97W. Expect N gale-force winds and sea heights reaching 8 feet to the NW of the cold front. Gale-force wind speeds are forecast in the Gulf of Mexico during the next 48 hours, as the cold front sweeps across the area. Please read the Atlantic high seas forecast, that is listed under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC, for more details about each area of gale-force winds. ...CARIBBEAN SEA GALE WARNING... The 12-hour forecast consists of NE gale-force winds and sea heights ranging from 11 feet to 14 feet from 11N to 13.5N between 74W and 77W. The 48-hour forecast consists of wind speeds slower than gale-force. Please read the Atlantic high seas forecast, that is listed under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC, for more details. ...THE ITCZ/THE MONSOON TROUGH... The Monsoon Trough reaches the coastal sections of Liberia near 05N09W to 03N13W to 02N18W. The ITCZ continues from 02N18W to 02N35W and 03N42W. Convective precipitation: widely scattered moderate to isolated strong from 03N to 10N between 40W and 50W. isolated moderate elsewhere from 10N southward from 60W eastward. High level clouds are to the south of the line that passes through 19N19W 15N41W 12N60W. ...DISCUSSION... ...THE GULF OF MEXICO... Upper level SW wind flow spans the entire Gulf of Mexico. Please refer to the SPECIAL FEATURES section for information about the accompanying gale-force wind speeds and sea heights. Convective precipitation: scattered moderate to isolated strong within 30 nm to 60 nm on either side of 23N96W 25N95W 27N93W 30N89W. ...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. IFR: KEHC, KGHB, KGRY, KMDJ, KIKT. MVFR: KHHV, KVAF, KEMK, KGUL, KHQI, KGBK, KVQT, KATP, KVOA, and KDLP. LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA... TEXAS: MVFR in Brownsville and Port Isabel in the Lower Valley. LOUISIANA: MVFR in the southern coastal plains. Rain around Lake Pontchartrain, and in the SE corner of the state along the coast. MISSISSIPPI: MVFR mostly/some IFR in the southernmost coastal sections of the state. ALABAMA: MVFR in the southernmost coastal sections of the state. FLORIDA: rain and MVFR from Tallahassee westward. IFR in Perry. MVFR from Cross City to sections of Tampa/St.Petersburg metropolitan area. MVFR in Naples. light rain and MVFR at the Key West International Airport. ...THE CARIBBEAN SEA... An upper level ridge extends from the northern Colombia, in the part that is from 10N northward, northwestward, to the Yucatan Channel. High level clouds are curving anticyclonically across the open waters of the Caribbean Sea. Rainshowers are possible in areas of broken low level to middle level clouds. The monsoon trough is along 09N between 74W in northern Colombia beyond 83W in southern Costa Rica. Convective precipitation: possible rainshowers from 11N southward from 80W westward. 24-HOUR rainfall totals in inches for the period ending at 18/1200 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 0.59 in San Juan in Puerto Rico, 0.19 in St. Thomas in the U.S.A. Virgin Islands, 0.07 in Guadeloupe, 0.03 in Freeport in the Bahamas, and 0.02 in Curacao and Trinidad. ...HISPANIOLA... Upper level NW 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: nearby rainshowers. MVFR. ceiling 2000 feet. La Romana: MVFR. ceiling 2200 feet. Punta Cana: VFR/no ceiling. Santiago: few cumulonimbus clouds. Puerto Plata: MVFR. ceiling 1600 feet. The GFS MODEL forecast for 250 MB shows that NW wind flow will move across the area for the first 24 hours. A ridge will settle across Hispaniola, with broad anticyclonic wind flow for day two. The GFS MODEL forecast for 500 MB shows that NE wind flow will move across the area, with an Atlantic Ocean-to-Gulf of Mexico ridge. The GFS MODEL forecast for 700 mb shows that E-to- NE wind flow will move across the area, with an an Atlantic Ocean-to-Gulf of Mexico ridge. ...THE ATLANTIC OCEAN... The upper level cyclonic wind flow that was associated with a central Atlantic Ocean upper level trough from 24 hours ago has moved to the north of the area. A cold front passes through 32N37W and it reaches 31N40W. A dissipating stationary front continues from 31N40W to 28N50W to 25N60W and 25N67W. Convective precipitation: isolated moderate to locally strong from 27N to 30N between 40W and 51W. Rainshowers are possible elsewhere to the north of the line that passes through 32N34W 29N40W 26N50W 25N62W. An upper level trough extends from a Morocco cyclonic circulation center to 22N21W 18N27W, to a 16N43W cyclonic circulation center. No significant deep convective precipitation is apparent in satellite imagery. A surface ridge passes through 32N31W beyond 24N17W, into Africa, to the southeast of the dissipating stationary front. A surface ridge passes through Bermuda, to 31N70W and 29N76W, beyond central Florida. Surface anticyclonic wind flow is to the north and northwest of the dissipating stationary front. For additional information please visit http://www.hurricanes.gov/marine $$ MT