000 AXNT20 KNHC 201804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 204 PM EDT THU OCT 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. ...SPECIAL FEATURES... An elongated area of surface low pressure is about 200 nm to the NE of the Central Bahamas, moving northwestward about 10 mph. This system has become slightly better organized since yesterday. It is possible, still, that it may become a subtropical or tropical cyclone before it merges with a cold front that is forecast to be in the western Atlantic Ocean on Friday night. A NOAA reconnaissance aircraft is scheduled to investigate the area this afternoon. It is possible that locally heavy rainfall may reach parts of Hispaniola today. The chance of formation into a tropical cyclone is medium. An upper level trough extends from the Atlantic Ocean near 31N71W to 25N73W, into the NW corner of the Caribbean Sea, to the coast of Mexico and Belize. Convective precipitation: scattered strong from 16N to 19N between 68W and 74W around Hispaniola. Widely scattered moderate to isolated strong in the Atlantic Ocean from 20N to 30N between 63W and 70W, and from 27N to 30N between 70W and 75W, and from 24N to 32N between 55W and 62W. Surface low pressure covers the Atlantic Ocean from 20N northward from 60W westward. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 40W from 16N southward, moving westward 10 to 15 knots. Convective precipitation: widely scattered moderate to isolated strong, and mixed with Monsoon Trough precipitation, from 08N to 13N between 33W and 45W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough passes through the coastal sections of Guinea- Bissau near 12N16W, to 09N23W 09N37W 08N43W. Convective precipitation: scattered strong from 09N to 10N between 41W and 43W, and from 11N to 12N between 44W and 45W. Rainshowers are possible elsewhere from 18N southward between 10W and 46W. ...DISCUSSION... ...THE GULF OF MEXICO... Upper level anticyclonic wind flow spans the Gulf of Mexico. Comparatively drier air in subsidence is apparent in water vapor imagery from 93W eastward. Broad surface anticyclonic wind flow covers the area from 93W eastward. Upper level cyclonic wind flow extends from the Atlantic Ocean, across Florida, into the SE corner of the Gulf of Mexico. This cyclonic wind flow is a result of an upper level trough that extends from 31N71W to 25N73W, into the NW corner of the Caribbean Sea, near the coast of Mexico and Belize. A surface trough is in the Texas coastal plains, in advance of a cold front that is moving through central Texas at this moment. Convective precipitation: scattered moderate to isolated strong within 90 nm of the Texas coast. A second surface trough is in the SW corner of the Gulf of Mexico, from the deep south of Texas to the northern part of the Isthmus of Tehuantepec of southern Mexico. Convective precipitation: isolated moderate within 60 nm to 90 nm of the coast from Texas to 20N91W. ...FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD... LIFR: none. IFR: none. MVFR: none. 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 Port Isabel. light rain in Harlingen. rainshowers and thunder in Huntsville. light rain at the Houston Hobby Airport. MVFR at the Houston Intercontinental Airport. LOUISIANA: MVFR in Lake Charles and Lafayette. MISSISSIPPI/ALABAMA/FLORIDA: VFR/no ceilings. ...THE CARIBBEAN SEA... Upper level cyclonic wind flow covers the area to the W and NW of the line from 20N70W and the Dominican Republic, to 16N73W, to eastern sections of Honduras. This cyclonic wind flow is related to the upper level trough that is described in the Special Features section that is at the beginning of this bulletin. Some of this cyclonic wind flow also is spilling over into the SE corner of the Gulf of Mexico. Upper level cyclonic wind flow is reaching parts of the eastern Caribbean Sea, at the edge of the cyclonic wind flow that is moving around an Atlantic Ocean 10N53W cyclonic circulation center. Comparatively drier air in subsidence is apparent in water vapor imagery in the area of the cyclonic wind flow. 24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT 20/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...1.89 in Tegucigalpa in Honduras; 0.25 in Guadeloupe; 0.03 in Nassau in the Bahamas and in St. Thomas in the Virgin Islands; and 0.01 in Merida in Mexico. ...HISPANIOLA... Please refer to the Special Features section, that is at the beginning of this bulletin, for more information about an Atlantic Ocean low pressure center and related rainfall. It is possible that locally heavy rainfall may reach parts of Hispaniola today. An upper level trough extends from the Atlantic Ocean near 31N71W to 25N73W, into the NW corner of the Caribbean Sea, to the coast of Mexico and Belize. Convective precipitation: scattered strong from 16N to 19N between 68W and 74W around Hispaniola. Upper level SW wind flow is moving across Hispaniola. SURFACE OBSERVATIONS...FOR PORT-AU-PRINCE IN HAITI: rain for the last several observations. FOR THE DOMINICAN REPUBLIC...Barahona: VFR/no ceilings; few cumulonimbus clouds. Santo Domingo: rainshowers and thunder. La Romana: rainshowers and thunder... temporarily MVFR for the last observation. Punta Cana: rainshowers. Santiago: MVFR. Puerto Plata: VFR/no ceilings; few cumulonimbus clouds. The GFS MODEL forecast for 250 MB shows that SW wind flow for most of day one eventually will become W wind flow, with a Caribbean Sea ridge. Anticyclonic wind flow will cover the entire area during day two. The GFS MODEL forecast for 500 MB shows that SW wind flow will move across the area for the next 48 hours. The GFS MODEL forecast for 700 MB show that S to SW wind flow will move across the area during day one, eventually become purely SW wind flow. Day two will consist of more SW wind flow, becoming anticyclonic with a ridge by the end of day two. ...THE ATLANTIC OCEAN... An upper level cyclonic circulation center is near 10N53W. Upper level cyclonic wind flow covers the Atlantic Ocean from 03N to 20N between 45W and 63W. A surface trough is along 22N47W 20N50W 18N51W 14N52W. Convective precipitation: isolated moderate to locally strong is in the Atlantic Ocean from 05N to 14N between 46W and 54W. An upper level trough extends from 35N27W to a 29N40W cyclonic circulation center. Upper level cyclonic wind flow covers the Atlantic Ocean from 22N northward between 20W and 44W. A surface trough is along 32N29W 27N38W 25N47W. Convective precipitation: rainshowers are possible to the N and NW of the line that passes through 32N23W 21N38W 23N53W. For additional information please visit http://www.hurricanes.gov/marine $$ MT