000 AXNT20 KNHC 152319 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 719 PM EDT Sun Sep 15 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 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... Tropical Storm Humberto is centered near 29.3N 78.0W at 15/2100 UTC or 180 nm NNW of Great Abaco Island moving N at 5 kt. Estimated minimum central pressure is 989 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Numerous moderate to scattered strong convection extends outward from the center 100 nm NW quad, from 90 nm NE quad, 80 nm SE quad. On the forecast track, the center of Humberto will continue to move away from the Bahamas and remain well offshore of the southeastern coast of the United States through Wednesday. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC, or at the website hurricanes.gov for more details. ...TROPICAL WAVES... An eastern Atlantic tropical wave with axis along 23W from 04N-18N, is moving W around 15 kt. The wave shows up well in 700 mb trough diagnostics, the TPW imagery and latest ASCAT pass. Scattered showers are present in the vicinity of the wave axis. A central Atlantic tropical wave with axis along 40W from 04N- 16N, is moving W at around 15 kt. A 1008 mb surface low is centered along the wave axis near 09N40W. The wave is well depicted in satellite imagery and TPW imagery. Scattered moderate convection is noted from 08N- 12N between 38W-43W. Slow development is anticipated during the next day or two. Environmental conditions are forecast to become more conducive for development by the middle of the week, and a tropical depression is likely to form by the end of the week while the system moves slowly west-northwestward to northwestward. There is a low chance of development in the next 48 hours. A west-central Atlantic tropical wave with axis along 55W from 07N-21N, is moving W around 15-20 kt. This wave is well depicted in model guidance and satellite imagery. Scattered moderate convection is seen from 12N-21N between 55W-60W. The wave will bring enhanced rain to the Lesser Antilles and eastern Caribbean on Monday. An eastern Caribbean tropical wave extends its axis along 62W from 20N, moving west around 15 kt. This wave is well depicted in model guidance and satellite imagery also. Scattered moderate convection covers the area from 14N-18N between 62W-69W affecting the northern Leeward Islands and Puerto Rico. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from Guinea-Bissau near 15N17W to 11N32W to 08N44W. The ITCZ continues from 08N44W to 09N51W. Aside from the convection already discussed in the Tropical Waves section above, scattered moderate convection is noted within 90 nm on either side of the monsoon trough between 26W-35W. GULF OF MEXICO... The weather over the Gulf of Mexico is dominated by a large mid to upper-level low that is centered over the western portion of the basin. A surface trough is now being analyzed from the western Yucatan Peninsula near 25N90W to 18N91W. Upper- level diffluence and divergence on the east side of the upper-low are enhancing scattered to numerous moderate convection from 25N- 28N between 82W-93W. Scattered showers and tstorms are seen in the southern Bay of Campeche from 19N-21N between 90W-92W. The latest ASCAT pass and nearby observations depict gentle to moderate easterly winds across the northern half of the basin north of 24N, while gentle winds prevail south of 25N. The broad area of disorganized showers and thunderstorms over the northern Gulf of Mexico has some slight development possible during the next couple of days while it moves westward over the western Gulf of Mexico. The system is forecast to move inland along the northwestern Gulf coast by late Monday or Tuesday, and further development is not expected after that time. High pressure will gradually build over the Gulf Tue through Fri. CARIBBEAN SEA... Refer to the Tropical Waves section above for details on the tropical waves moving and approaching the basin. Relatively dry air covers the central Caribbean. In the SW Caribbean, scattered moderate to strong convection is noted int he vicinity of the monsoon trough affecting the Caribbean waters and portions of Central America south of 13N and west of 77W. The latest ASCAT pass depicts moderate to fresh trades in the south- central Caribbean, while gentle to moderate easterly winds prevail elsewhere. Moderate to fresh trade winds will dominate much of the basin. A tropical wave moving across the eastern Caribbean today will reach the central Caribbean on Mon. Another tropical wave will approach Barbados late today, move across the eastern Caribbean Mon, and into the central Caribbean through mid week, bringing widespread showers and thunderstorms, gusty winds and building seas. Northerly swell will reach the Atlantic passages into the Caribbean Sea late on Mon and then gradually subside through Wed. ATLANTIC OCEAN... Refer to the sections above for details on T.S. Humberto and the tropical waves moving across the basin. A mid-latitude low currently centered near 41N43W extends its cold front south entering the forecast area near 31N39W to 28N57W. The front becomes stationary from that point to 31N65W. A pre-frontal trough is analyzed from 30N37W to 25N48W with scattered showers. To the east, 1027 mb surface high centered to the north remains in control over this area. Humberto will strengthen to a hurricane near 29.8N 77.6W Mon morning, move to 30.1N 76.7W Mon afternoon, 30.4N 75.4W Tue morning, 30.7N 73.6W Tue afternoon, and 31.7N 68.9W Wed afternoon. Humberto will change little in intensity as it moves near 35.0N 62.0W Thu afternoon, and weaken to a tropical storm over 39.6N 56.1W Fri. Northerly swell will reach the Atlantic passages into the Caribbean Sea late on Mon and subside by Wed. $$ ERA