000 AXNT20 KNHC 151802 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 202 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 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... Tropical Storm Humberto is centered near 28.9N 77.9W at 15/1500 UTC, or 165 nm ENE of Cape Canaveral Florida, moving NNW at 6 kt. Estimated minimum central pressure is 997 mb. Maximum sustained wind speed is 75 kt with gusts to 90 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 east coast of Florida 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 is along 20W from 18N southward, 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 tropical wave with axis along 37W from 16N southward is moving W at 10-15 kt. The wave is well depicted in satellite imagery and TPW imagery. Scattered moderate convection is seen from 06N-12N between 36W-41W. Shower activity remains disorganized and only a slow development is anticipated during the next day or two. However, environmental conditions are forecast to become more conducive for gradual development through the middle of the week, and a tropical depression is likely to form by the end of the week while the system moves slowly westward or west-northwestward. There is a low chance of development in the next 48 hours. A central Atlantic tropical wave with axis along 53W from 06N-21N is moving W around 20 kt. This wave is well depicted in model guidance and satellite imagery. Scattered moderate convection is seen from 12N-17N between 51W-58W, and scattered showers south of 12N near the ITCZ. 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. Scattered moderate convection covers the area from 13N-18N between 61W-64W, including the islands of Dominica, Guadeloupe, St. Kitts, and other nearby islands. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from Guinea-Bissau near 13N16W to 10N30W to 07N44W. The ITCZ continues from 07N44W to 09N51W, then resumes west of the wave from 09N54W. Aside from the convection already discussed in the Tropical Waves section above, scattered moderate convection is noted within 180 nm of the monsoon trough between 24W-36W, and between 41W-47W. 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 central portion of the basin near 26N92W. There is a sharp trough at 850 and 925 mb over the south-central Gulf. 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 fresh easterly winds across the northern half of the basin north of 24N, while gentle winds prevail south of 24N. A large area of disorganized showers and thunderstorms over the central and eastern Gulf of Mexico is associated with an upper- level low and a weak surface trough. Some slight development of this system is 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. Weak high pressure will build over the Gulf through mid week. 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, no significant convection is seen in the western Caribbean Sea except with isolated showers and tstorm near Belize in the Gulf of Honduras. To the south, Scattered moderate strong convection is seen from Colombia, Panama and Costa Rica due to the proximity of the Pacific monsoon trough. Most of the convection has develop below 11N southward between 75W-83W. The latest ASCAT pass depicts fresh to strong trades in the south-central Caribbean. 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 due to a mid-latitude low centered near 40N43W. ATLANTIC OCEAN... Refer to the sections above for details on T.S. Humberto and the tropical waves moving across the basin. A storm-force mid-latitude low currently centered near 40N43W with a front extending south entering the forecast area near 31N40W to 27N51W to 30N63W. A surface trough ahead of the front is from 30N38W to 25N48W. Scattered showers and tstorms extend southeast 60 to 80 nm from the trough and along the frontal boundary. To the east, 1030 mb high pressure to the north remains in control across the area. Humberto will strengthen to a hurricane near 29.5N 77.7W this evening, move to 30.0N 77.1W Mon morning, 30.3N 75.9W Mon evening, 30.7N 74.4W Tue morning, and 31.6N 69.6W Wed morning. Humberto will change little in intensity as it moves to near 34.5N 62.8W early Thu, and continue to near 39.0N 57.0W Fri. Northerly swell will reach the Atlantic passages into the Caribbean Sea late on Mon. Northerly swell from a large, storm-force mid-latitude low currently centered near 40N43W, will reach the Atlantic passages into the Caribbean Sea late on Monday and continuing into mid- week. $$ Torres