000 AXNT20 KNHC 181121 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 721 AM EDT Thu May 18 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 0600 UTC surface analysis and satellite imagery through 1045 UTC. ...SPECIAL FEATURES... An upper level trough is digging through the area that is from western Cuba into eastern Honduras. A surface trough is along 25N79W, just to the west of Andros Island in the Bahamas, to central Cuba, to 20N81W and 18N81W in the Caribbean Sea. Convective precipitation: scattered moderate to strong from 14N to 17N between 72W and 80W. Scattered moderate to isolated strong in the western half of the Dominican Republic, from 80W westward. Serious flooding already has been reported in Haiti and Jamaica. Animated satellite imagery and model guidance suggest that this system only will move very slowly NE during the next 24 hours. Heavy rainfall will remain possible in Eastern Cuba, Jamaica and Hispaniola. Life-threatening flooding and mudslides remain a strong possibility. Please pay attention to advisories and bulletins from local meteorology offices, emergency management services, and other governmental agencies. Please refer to the METEO-FRANCE High Seas Forecast, that is listed on the website: WWW.METEOFRANCE.COM/PREVISIONS-METEO- MARINE/BULLETIN/GRANDLARGE/METAREA2. Gale-force winds are forecast for the areas that are called: AGADIR and CANARIAS. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 40W/41W from 10N southward, moving westward 10 to 15 knots. Convective precipitation: widely scattered moderate to isolated strong from 03N to 08N between 36W and 46W. A tropical wave is along 61W from 10N southward into South America, near Trinidad, moving westward 10 to 15 knots. Convective precipitation: isolated moderate from 08N to 10N between 58W and 63W...mostly inland. A Caribbean Sea tropical wave is along 78W from 15N southward, moving westward 10 knots. This wave is moving through the area of an upper level trough, part of the SPECIAL FEATURES section. Convective precipitation: isolated moderate from 13N southward from 75W westward. ...ITCZ/MONSOON TROUGH... The Monsoon Trough passes through coastal sections of Mauritania near 17N16W, 10N19W, and 07N21W. The ITCZ continues from 07N21W to 02N30W, to the Equator along 38W. Convective precipitation: numerous strong from 04N to 07N between 12W and 16W. Widely scattered moderate to isolated strong from 02N to 07N between 15W and 28W, and in coastal sections of Brazil and French Guiana from 02N to 05N between 51W and 54W. ...DISCUSSION... ...THE GULF OF MEXICO... Broad upper level anticyclonic wind flow is spanning the entire Gulf of Mexico. High level clouds are moving in the coastal areas from 23N along the coast of Mexico to the Florida Big Bend and the NE corner of the Gulf of Mexico. Some high level moisture also is moving across the SW corner of the Gulf of Mexico. Comparatively drier air in subsidence is apparent in water vapor imagery elsewhere. A surface trough is along the Florida west coast, from 26N to 30N. ...VISIBILITY IN MILES, AND WEATHER, FOR THE OFFSHORE OIL PLATFORM SITES, THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD... KMZG, KBBF, KBQX, and KVOA: 2 to 3, and mist. KXIH, KHHV, KVAF, KEMK, KGRY, and KMDJ: 3 TO 5 and mist. KVOA: 3 to 5 and haze. VISIBILITY IN MILES, AND WEATHER, FOR THE COASTAL PLAINS OF THE U.S.A., FROM THE DEEP SOUTH OF TEXAS TO FLORIDA... TEXAS: 5 and haze and mist from Victoria southward into parts of the middle Texas Gulf coastal plains and in parts of the Deep South. light rain near the IAH airport and near Tomball. LOUISIANA: 2 and mist in Baton Rouge. 5 and mist in Hammond. MISSISSIPPI: 5 and mist in Natchez. FLORIDA: Milton: 3 and light rain. Crestview: 4 and mist. St. Petersburg: 5 and mist. ...THE CARIBBEAN SEA... Upper level cyclonic wind flow covers the Caribbean Sea from 80W westward. This cyclonic wind flow is from the upper level trough that is associated with the rainfall, that is described in the SPECIAL FEATURES section. Upper level anticyclonic wind flow covers the area from 80W eastward. ...HISPANIOLA... Upper level SW wind flow is moving across Hispaniola. Please refer to the SPECIAL FEATURES section for more information. SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: MVFR. for the DOMINICAN REPUBLIC: Santo Domingo: VFR. La Romana and Punta Cana: VFR. Santiago and Puerto Plata: VFR. The GFS MODEL forecast for 250 mb shows that SW wind flow will move across the area during the next 24 hours, followed by westerly wind during day two. The current trough that is in the westernmost part of the Caribbean Sea will linger for at least another 24 hours to 48 hours. The upper level ridge will remain to the east of the trough. The GFS MODEL forecast for 500 mb shows that a short-wave trough will move across Hispaniola early during day one of the 48-hour forecast period. It will continue for much if not all of the forecast period. Expect cyclonic wind flow during the time of the presence of the trough. The GFS MODEL forecast for 700 mb shows that SE and S wind flow will move across Hispaniola during the first 24 hours, with an Atlantic Ocean-to- Hispaniola east-to-west oriented ridge. Expect SE wind flow during day two, with an inverted trough that will be across Hispaniola. ...THE REST OF THE ATLANTIC OCEAN... An upper level trough passes through 32N43W, to 26N48W. A cold front passes through 32N48W to 31N50W. Convective precipitation: broken to overcast multilayered clouds and possible rainshowers cover the area from 20N northward between 34W and 55W. A surface ridge extends from a 1031 mb high pressure center that is near 41N26W through 32N38W and to 28N50W. A 1024 mb high pressure center is near 32N64W. Surface anticyclonic wind flow covers the Atlantic Ocean from 15N northward between 50W and 80W. For additional information please visit http://www.hurricanes.gov/marine $$ MT