548 AXNT20 KNHC 101729 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 129 PM EDT Tue Sep 10 2019 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 1710 UTC. ...SPECIAL FEATURES... Gabrielle has become an extratropical cyclone, and the final advisory was issued at 10/1500 UTC. At 10/1500 UTC, the center of Post-Tropical Cyclone Gabrielle is near 43.9N 37.8W, or about 605 nm NW of the Azores, moving NE at 25 kt. The estimated minimum central pressure is 998 mb. The maximum sustained winds are 45 kt gusting to 55 kt. Scattered moderate rainshowers extend outward to 300 nm in the N semicircle. Please read the final NHC forecast/advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC, or the website hurricanes.gov for more details. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 21W, from 20N southward, moving W at 10 kt. Scattered moderate showers are near and within 210 nm E of the wave axis from 13N-19N. Scattered moderate showers are also from 03N-08N between 15W-27W. The wave is expected to move westward quickly during the next several days. Some slow development is possible late this week and over the weekend when the system is several hundred nm east of the Lesser Antilles, and there is a low chance of tropical cyclone formation within the next 5 days. An Atlantic Ocean tropical wave is along 47W, from 20N southward, moving W at 10-15 kt. A 1011 mb low is along the wave near 13N. Scattered moderate showers are from 10N-15N between 43W-51W. Although some slight development is possible today or tomorrow, upper level winds are forecast to become unfavorable for tropical cyclone formation by Thursday. There is a low chance of tropical cyclone formation during the next 2 days. This disturbance is expected to move slowly westward for the next several days. A tropical wave is in the eastern Caribbean Sea along 64W from 17N southward, moving W around 15 kt. Scattered showers and tstorms are mostly inland over NE Venezuela, with only isolated showers seen over water east of the wave axis near the Lesser Antilles. A western Caribbean Sea tropical wave is along 83/84W, from 17N southward, moving W around 10 kt. The wave is interacting with the East Pacific monsoon trough to produce scattered moderate convection from 08N-12N between 80W-83W. A tropical wave is inland, along 91W, from 19N southward, moving W at 10-15 kt. The wave passes through the western Yucatan Peninsula, to western Guatemala and into the East Pacific basin. Isolated showers are near the wave axis. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal sections of Senegal near 16N17W to 12N20W to 12N30W to 13N40W to a 1011 mb low near 13N47W to 09N52W. The ITCZ extends from 09N52W to 09N60W. Scattered showers are within 270 nm N and 180 nm S of the monsoon trough between 27W-43W. GULF OF MEXICO... Middle level to upper level cyclonic wind flow covers northeastern Mexico, E Texas and the Gulf of Mexico from 22N northward between 93W-102W. A diurnally induced surface trough is over the central Bay of Campeche. Scattered moderate convection is south of 24N between 92W-96W. Scattered showers and isolated tstorms are seen elsewhere S of 29N and W of 91W. Scattered showers and tstorms are also noted over the eastern Gulf of Mexico from 24N-28N between 82W-87W due to enhanced moisture in the area. Scattered showers and tstorms are also occurring in the Yucatan Channel. The latest ASCAT pass shows mostly moderate wind speeds over the basin. Weak high pressure will continue just north of the western and central Gulf through this week maintaining gentle to moderate easterly flow throughout. Stronger high will build in from the northeast across Florida and the eastern Gulf through Fri allowing for fresh northeast to east winds to exist over the eastern Gulf and fresh to strong winds over the Straits of Florida. A surface trough is expected to move across Florida from the Atlantic Fri and Fri night and into the eastern Gulf of Mexico this weekend accompanied by scattered to numerous showers and thunderstorms. Environmental conditions could become conducive for slow development when the trough moves through the Gulf of Mexico over the weekend. There is a low chance of tropical cyclone formation during the next 5 days over the Gulf of Mexico from this trough. CARIBBEAN SEA... See section above for information on the tropical waves traversing the basin. An upper level trough and a surface trough, both near the eastern Bahamas, extend moisture southward to Haiti, the Windward Passage and Jamaica. Scattered showers and isolated tstorms are seen north of 17N between 72W-78W. Additional scattered tstorms are in the NW Caribbean from 20N-22N between 80W-86W. In the SW Caribbean, the East Pacific monsoon trough is inducing scattered moderate convection S of 12N and W of 78.5W. Latest ASCAT pass shows strong trades in the south-central Caribbean from 11.5N-13.5N between 71.5W-76W. High pressure ridging will remain to the north and northeast of area through the remainder of the week. The ridging will maintain moderate trades, except pulsing to fresh to strong in the south- central Caribbean and near the coast of Colombia through the next few days. A tropical wave over the eastern Caribbean near 64W will move into the central Caribbean by late Wednesday then enter the western Caribbean Friday. A stronger tropical wave may approach the tropical N Atlc and far eastern Caribbean by the end of the upcoming weekend with gusty winds and squalls. ATLANTIC OCEAN... A surface trough axis extends from 26N69W to 18N72W. Numerous moderate convection is from 21N-27N between 67W-74W, including over portions of the SE Bahamas. Scattered showers and isolated tstorms are elsewhere from 20N-30N between 66W-75W. An upper-level cyclonic circulation center near 27N74W is enhancing convection. The surface trough will track WNW across the Bahamas through Thu night before reaching Florida Fri. The trough will be accompanied by scattered to numerous showers and tstorms. Some of these thunderstorms could be severe across the Bahamas, especially Thursday into Friday. Heavy rainfall is likely in the SE and Central Bahamas Wed and Thu, spreading to the Central and NW Bahamas on Friday. The system has little to no tropical cyclone formation potential before it reaches Florida, but environmental conditions could become a little more conducive for development over the weekend when the trough is located over the Gulf of Mexico. A surface trough extends from 31N53W to 27N54W. An upper level low is just south of that, near 24N55W. Scattered moderate convection is from 23N-26.5N between 50W-55W. Farther E, a surface trough along 42W from 28N-31N is inducing scattered showers near the trough axis. A large upper level low near 26N31W is producing scattered showers and isolated tstorms from 26.5N-31N between 28.5W-33.5W. Strong high pressure centered north of the area will expand eastward through Wed night, then weaken on Thu into Fri as the surface trough moves through the Bahamas to Florida. $$ Hagen