000 AXNT20 KNHC 120605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 AM EST SAT NOV 12 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 0000 UTC surface analysis and satellite imagery through 0515 UTC. ...SPECIAL FEATURE... ...A GALE WARNING IN THE GULF OF MEXICO... A reinforcing cold front is forecast to move southward across the Gulf of Mexico Saturday night and Sunday. A surface ridge will surge southward across eastern Mexico. Northerly winds will increase in speed to minimal gale force starting on Saturday evening, and then they will diminish to less than gale force shortly after sunrise on Sunday. The sea heights will build locally to 12 feet during the times of the fastest wind speeds. Please read the HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC... and the OFFSHORE FORECAST...MIAOFFNT4/FZNT24 KNHC...for more details. ...THE ITCZ/THE MONSOON TROUGH... The Monsoon Trough reaches the coastal areas of Guinea-Bissau near 12N16W, to 06N22W. The ITCZ continues from 06N22W to 04N25W and 07N43W. Convective precipitation: isolated moderate from 10N southward from 40W eastward. ...DISCUSSION... ...THE GULF OF MEXICO... Upper level anticyclonic wind flow is moving from Mexico near 20N100W, across the Gulf of Mexico, and beyond Florida. A SE-to-NW oriented surface trough extends from the coastal waters of NW Cuba into the central Gulf of Mexico. A stationary front continues from the central Gulf of Mexico, and it curves westward and southward, into the SW corner of the Gulf of Mexico. A north-to-south oriented surface trough is between 90W and the stationary front. Convective precipitation: rainshowers are possible in much of the area, except for parts of the area that are from 26N southward from 89W eastward. A surface ridge passes through the deep south of Texas, through the coastal plains of Mexico, into the Isthmus of Tehuantepec of southern Mexico. Gale-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: 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: VFR/no ceilings. LOUISIANA: LIFR in Patterson. MISSISSIPPI: LIFR in Pascagoula. ALABAMA: VFR/no ceilings. FLORIDA: MVFR in Brooksville and Sarasota. ...THE CARIBBEAN SEA... Upper level anticyclonic wind flow is moving across the area, from Central America and South America, toward the NE, and across the open waters of the Caribbean Sea. A surface trough is along 71W/72W from the Dominican Republic to La Peninsula de la Guajira of NE Colombia. Convective precipitation: isolated moderate between 66W and 74W. A NW-to-SE oriented surface trough extends from parts of the NW Caribbean Sea into the SW corner of the area. The monsoon trough is along 10N between Colombia and Costa Rica. Convective precipitation: scattered to numerous strong from 14N southward from 73W westward. The 24-HOUR rainfall total in inches for the period ending at 12/0000 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...is 0.01 in Guadeloupe. ...HISPANIOLA... Upper level NW wind flow is moving across the area. Convective precipitation: isolated moderate to locally strong in the coastal waters of eastern Hispaniola. some precipitation is inland also. SURFACE OBSERVATIONS...for Port-au-Prince in Haiti, at 12/0100 UTC: VFR...a ceiling at 5000 feet. for the DOMINICAN REPUBLIC: Barahona at 12/0000 UTC: rain and thunder. Santo Domingo: VFR/ no ceilings. few cumulonimbus clouds. La Romana: VFR/no ceilings. Punta Cana: VFR/no ceilings. few cumulonimbus clouds. Santiago; VFR. few cumulonimbus clouds. ceiling at 8000 feet. Punta Cana: VFR. ceiling at 7000 feet. The GFS MODEL forecast for 250 MB shows that an anticyclonic circulation center will move from the Yucatan Peninsula into the NW corner of the Caribbean Sea, during day one. Expect NW wind flow during day two. The GFS MODEL forecast for 500 MB shows that anticyclonic wind flow will be present across Hispaniola during day one. Expect NW and N wind flow across the area during day two. An anticyclonic circulation center will form in the area that is between the Cayman Islands, SE Cuba, and Jamaica. The GFS MODEL forecast for 700 mb shows that S wind flow, with an east-to-west oriented ridge, will move across the during the first half of day one. Expect anticyclonic wind flow across the area during the second half of day one, with a separate anticyclonic circulation center. More anticyclonic wind flow will move across the area from the second half of day one into the middle of day two. The second half of day two will consist of N-to-NE wind flow, in a large- scale ridge, whose anticyclonic wind flow is forecast to cover parts of the Gulf of Mexico, the Caribbean Sea, and the Atlantic Ocean. ...THE ATLANTIC OCEAN... Upper level cyclonic wind flow covers the area from 20N northward from 50W westward. An upper level trough that is in the area is supporting a cold front that passes through 32N58W to a 1010 mb low pressure center that is near 28N60W. A cold front continues from the 1010 mb low center, to 25N62W, 23N70W, and 22N79W in Cuba. Convective precipitation: in the Atlantic Ocean and in the Caribbean Sea: widely scattered moderate to isolated strong from 22N northward between 50W and 60W, from 19N to 22N between 64W and the Windward Passage including off the NE coast of Hispaniola, and in the Caribbean Sea from 16N to 20N between 66W and 71W. Rainshowers are possible elsewhere in the Atlantic Ocean from 20N between 50W and 70W. An upper level cyclonic circulation center is near 22N34W. Upper level cyclonic wind flow covers the area from 18N northward between Africa and 45W. Convective precipitation: rainshowers are possible in the area of upper level cyclonic wind flow. Surface anticyclonic wind flow covers the Atlantic Ocean from 20N northward between Africa and 50W. Upper level cyclonic wind flow and a trough have moved into Africa mostly. Some residual deep layer cyclonic wind flow remains from 15N northward and from 20W eastward. A surface trough is along 31N10W to 28N18W to 25N17W. Rainshowers are possible from 17N northward from 20W eastward. A central Atlantic Ocean surface ridge is along 20N50W to 27N45W beyond 32N43W. A second surface ridge is in the eastern Atlantic Ocean, from the Cabo Verde Islands to beyond 32N26W. For additional information please visit http://www.hurricanes.gov/marine $$ MT ...ITCZ/MONSOON TROUGH... The monsoon trough axis extends across Africa into the east Tropical Atlantic near 12N16W to 07N22W. The intertropical convergence zone axis extends from 07N22W to 05N40W to 10N60W. Scattered moderate and isolated strong convection is within 180 nm northeast of the axis between 40W and 50W. Scattered moderate convection is within 180 nm north of the axis west of 55W. ...DISCUSSION... ...GULF OF MEXICO... West-southwesterly flow aloft prevails over the Gulf early this evening between upper level ridging extending from the southeast Gulf to the southwest Gulf, and a broad middle to upper level low approaching the Texas panhandle from the west-northwest. Moisture and cloudiness continues to stream northeastward across northeast and central Mexico, then across the Gulf northwest of the upper ridging. Scattered to numerous showers and isolated thunderstorms are likely across the same area of the upper level moisture, with mainly dry conditions southeast of the upper ridging. A stationary front extends from the central Gulf near 25N90W to 24.5N94W to 1016 mb low pressure near 22N96W to the coast of southeast Mexico near 18N94W. Fresh to near gale force winds are reported within 150 nm north and northwest of the stationary front, while mainly gentle to moderate easterly flow is found elsewhere across the basin. The front will linger through Saturday, eventually merging with a new front which is described in the special features section above. CARIBBEAN SEA... Southerly upper level flow continues across much of the Caribbean basin early this evening, except westerly over the waters north of 15N, around an upper level anticyclone over northern South America. This flow is advecting middle to upper level moisture from the deep tropics to the north. Very heavy rainfall is likely occurring from western Colombia to across Costa Rica and Panama, as well as portions of Nicaragua. Water vapor satellite imagery indicates relatively dry air aloft north of 15N as a middle to upper level trough extends into the northwest Caribbean from 22N80W to the Gulf of Honduras. At the surface, a trough, which has the characteristics of a tropical wave, extends from the southern coast of the Dominican Republic to 1011 mb low pressure near 15N72W to 13N73W. Mainly moderate trades are observed across the basin, except locally fresh across the approach to the Windward Passage. The trough and low are forecast to dissipate through Saturday as they drift westward. Winds will increase locally to strong across the approach to the Windward Passage by late Saturday night, with little change otherwise. ...HISPANIOLA... A few isolated showers and thunderstorms developed over the Island during the afternoon hours as a middle to upper level trough nears the area from the west-northwest, supporting a surface trough which extends toward the north coast of the island from the northeast. Convection will likely diminish through the evening with the loss of daytime heating, with isolated activity likely to develop again on Saturday with a similar weather pattern in place. ATLANTIC OCEAN... A middle to upper level trough extends across the southwest north Atlantic, extending from a vigorous upper level low centered well north of the discussion area near 39N57W, southward through 25N60W, then southwest toward eastern Cuba. Very dry and stable air continues to fill in behind this upper feature, which is supporting a surface cold front extending from 32N54W to the southeast Bahamas. Numerous showers and scattered thunderstorms are occurring within 210 nm north of 24N ahead of the front. Surface high pressure is building in behind the front with a west to east ridge axis oscillating between 25N and 27N. The eastern portion of the trough will continue to progress eastward, while the western portion dissipates through early Saturday. A new cold front will move into the northwest waters off of the southeast U.S. coast Saturday night, stalling along 30N or 31N into Sunday as high pressure ridging blocks further progress of the front. The remainder of the basin is under the influence of a surface ridge, anchored by a nearly stationary 1030 mb high centered southeast of the Azores near 36N23W. For additional information please visit http://www.hurricanes.gov/marine $$ MT