000 AXNT20 KNHC 272354 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 754 PM EDT TUE SEP 27 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 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... Tropical wave extends from 08N56W to 19N53W moving W at 15 kt. A 1008 mb low is centered along the wave axis near 13N with global model data indicating 700 mb troughing between 50W-58W on the southern periphery of a mid-level ridge anchored near 24N49W. 850 mb relative vorticity is also maximized in the vicinity of the low center. Scattered moderate and isolated strong convection is from 11N-17N between 50W-57W. Regardless of tropical cyclone development...near gale to gale force winds are forecast to develop by 28/0600 UTC as the low approaches Barbados with heavy rainfall anticipated for the many of the Lesser Antilles. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/ FZNT02 KNHC for more details. ...TROPICAL WAVES... Tropical wave extends from 03N25W to 14N24W moving W at 20-25 kt. The wave coincides with 700 mb troughing between 15W-30W and largely remains embedded within the Monsoon Trough axis as a low- amplitude monsoonal gyre centered along the axis near 08N. Isolated moderate convection is from 04N-11N between 19W-28W. Tropical wave extends from 10N74W to 19N73W moving W at 10-15 kt. The wave coincides with subtle 700 mb troughing across the SW Caribbean Sea generally S of 15N between 75W-80W with 850 mb relative vorticity model fields indicating maximum values over the near shore waters of Colombia and across western Colombia itself. Isolated moderate convection is from 10N-12N between 73W-76W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 14N17W to 07N25W to 07N40W. Scattered moderate and isolated strong convection is from 10N-15N between 12W-18W. Widely scattered moderate convection is from 04N-13N between 28W-44W. ...DISCUSSION... GULF OF MEXICO... A broad middle to upper level trough is noted on water vapor imagery over much of eastern CONUS dipping its broad base over the SE CONUS this evening. The troughing supports a cold front extending from the NE Alabama SW to southeastern Louisiana and into the Gulf basin near 30N92W. The front meanders SW to 28N95W then southward to the east-central Mexico coast near Tampico. While much of the energy aloft supporting the front is over the CONUS...an upper level anticyclonic circulation is centered over east-central Mexico providing for an overall diffluent environment over the western Gulf. Scattered showers and tstms are occurring primarily S of 27N W of 90W in association with the low-level convergence in the vicinity of and SE of the front...and maximum middle to upper level diffluence. The remainder of the basin is under the influence of NW flow on the eastern periphery of the upper level ridging with mostly light to gentle anticyclonic surface winds occurring E of 90W. The front is expected to remain nearly stationary for the next 24 to 36 hours and begin progressing eastward by early Thursday across the NE Gulf waters and SE CONUS. A weak impulse of energy will sweep across the lower Mississippi River valley on Thursday...however the lingering stationary front extending from the NE Gulf to the NE Mexico coast will slowly become diffuse through upcoming weekend into Monday of next week. CARIBBEAN SEA... Upper level troughing extends over the western Caribbean between 77W-83W providing an overall unstable environment N of 17N for Jamaica and most of Cuba. Scattered showers and tstms are occurring across the NW Caribbean waters and portions of inland Cuba in association with the base of the upper level troughing. Farther south across the SW Caribbean...a tropical wave is along 74W moving westward and along with close proximity to the Monsoon Trough...scattered showers and tstms are occurring S of 15N between 77W-83W...including portions of Panama. Otherwise...a few isolated showers and tstms are occurring in the vicinity of Puerto Rico and across inland portions of Hispaniola...however much of the eastern and central Caribbean is under mostly clear skies and fair conditions. Looming to the east of the Lesser Antilles is the special features tropical wave with 1008 mb low centered along the wave axis near 13N. The wave is expected to approach the islands and by Wednesday evening bring rainfall and gusty winds to the region. Global models indicate the low tracking generally westward to the central Caribbean and then heading north between 70W-80W into the SW North Atlc by Monday morning. ...HISPANIOLA... A few isolated showers and tstms linger across the island this evening...however relatively dry air aloft prevails. A tropical wave is expected to continue moving west of the Windward Passage region as mostly fair skies and conditions are expected for Wednesday. ATLANTIC OCEAN... A middle to upper level shortwave trough is noted on water vapor imagery over the Florida peninsula and portions of the far western SW North Atlc. This shortwave is progressing north-northeastward as part of a broader middle to upper level trough currently over much of the eastern CONUS. A weak 1012 mb low is centered near 31N80W with a surface trough extending from the low to 28N79W then SW to 25N81W. Scattered showers and tstms are occurring S of 29N W of 76W. Farther east...southwesterly flow aloft prevails providing an overall diffluent environment to support another area of scattered showers and tstms occurring N of 26N between 69W-75W. Otherwise...the remainder of the central and eastern Atlc is under the influence of a surface ridge anchored by a 1022 mb high centered near 26N45W. A weakening front extends into the discussion area near 32N42W then generally westward to 29N54W but provides little sensible weather at this time. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN