000 AXNT20 KNHC 141104 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 704 AM EDT Sat Sep 14 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 0600 UTC surface analysis and satellite imagery through 1050 UTC. ...SPECIAL FEATURES... Tropical Storm Humberto is centered near 26.3N 76.0W at 14/0900 UTC or 60 nm E of Great Abaco Island moving NW at 6 kt. Minimum central pressure is 1007 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered moderate to isolated strong convection extends outward 180 nm NE quad. Numerous moderate to scattered strong convection extends outward 270 nm SE quad. Little to no convection is in the western semicircle. On the forecast track, the system is anticipated to move near or over the northwestern Bahamas today, and offshore of the east coast of Florida this weekend and early next week. Gradual strengthening is forecast, and Humberto is expected to become a hurricane by Sunday night. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC, or go to the website hurricanes.gov for more details. ...TROPICAL WAVES... An eastern Atlantic tropical wave is along 34N from 05N-16N, moving W at 15-20 kt. The wave is well depicted in satellite imagery and TPW imagery. Scattered moderate convection is from 07N-13N between 30W-38W. Gradual development of this system is possible during the next several days, and a tropical depression could form early next week while it moves westward across the tropical Atlantic. A central Atlantic tropical wave is along 45W from 06N-21N, moving W at 15-20 kt. Scattered showers are within 180 nm of the wave axis from 12N-23N. This wave is well depicted in model guidance, and satellite imagery shows turning. Conditions could become a little more conducive for development in a few days when the wave moves over the eastern Caribbean Sea. An Atlantic tropical wave is along 57/58W, from 08N-21N, moving west around 15 kt. Scattered moderate showers are within 180 nm of the wave axis from 13N-18N. TPW imagery and 700 mb streamline analysis depict the wave well. A western Caribbean tropical wave is along 86W from 18N southward, moving W around 15 kt. Scattered moderate showers are over the SW Caribbean S of 15N and W of 76W, and over portions of Central America. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from Senegal near 14N17W to 11N20W to 08N44W. The ITCZ is from 08N46W to 06N57W. Aside from the convection already discussed in the Tropical Waves section, an area of convection embedded in the monsoon trough near 39W is being monitored with a low chance of tropical cyclone formation during the next 48 hours. Scattered moderate convection is from 08N-10N between 38W-41W. Another area of scattered moderate convection, associated with a surface trough, is just N of the ITCZ from 08N-13N between 47W-52W. Scattered showers are within 180 nm N and 360 nm S of the monsoon trough between the W coast of Africa and 30W. GULF OF MEXICO... The weather over the Gulf of Mexico is dominated by a large upper-level low that is centered over the central portion of the basin near 26N90W, but spans nearly the entire Gulf. Upper-level diffluence on the east side of the upper low is producing numerous moderate with embedded isolated strong convection from 23N-28N between 82W-85W. Scattered moderate convection is from 27N-30N between 85W-91W. Elsewhere N of 22N and E of 93W, scattered showers and tstorms are seen. Only slow development of this system is likely during the next couple of days. However, conditions could become more conducive for tropical cyclone development early next week as the system moves over the western Gulf of Mexico. Elsewhere across the basin, scattered showers are seen in the SW Gulf from 18N-22N, west of 94W due to enhanced moisture in the area. The latest ASCAT pass shows moderate to fresh ENE winds across much of the Gulf. Fresh to strong NE to E winds will persist over the eastern Gulf today, between high pressure over the Mississippi Valley and Tropical Storm Humberto near the Bahamas. Winds and seas will diminish tonight into Sun as Humberto moves farther north off the northeast coast of Florida. Scattered to numerous showers and thunderstorms will continue across much of the eastern Gulf through Sun as an upper-level low lingers over the central Gulf. A weak pressure pattern will persist from late Sun through mid week as high pressure builds over the area. CARIBBEAN SEA... Refer to the Tropical Waves section above for details on the tropical wave moving across the western Caribbean. Relatively dry air covers much of the Caribbean Sea, including the central Caribbean. In the SW Caribbean, a line of scattered moderate to strong convection is within 45 nm of a line from 09N76W to 10.5N79W to 13.5N83W. A surface trough extends over Cuba and the NW Caribbean from 23N78W to 21N85W. Isolated showers are over the NW Caribbean N of 19N between 73W-87W. Scattered showers and tstorms are also seen over the NE Caribbean due to an approaching tropical wave. The latest ASCAT pass shows fresh trades over the south-central Caribbean, south of 16N between 64W- 77W. High pressure north of the area will maintain moderate trades, pulsing to fresh to strong in the south central Caribbean mainly at night. A tropical wave over the Gulf of Honduras will move inland today. Another tropical wave nearing Barbados will move across the eastern Caribbean today, through the central Caribbean Sun and Mon, and through the western Caribbean mid week. A third and stronger tropical wave will approach the Barbados Sun, move across the eastern Caribbean Mon, and into the central Caribbean through mid week, bringing widespread showers and thunderstorms, gusty winds and building seas. ATLANTIC OCEAN... Refer to the sections above for details on T.S. Humberto and the three tropical waves moving across the basin. Upper-level troughing covers the area north of 23N between 52W- 65W. Upper-level diffluence near the base of this trough is giving way to scattered moderate convection from 21N-26N between 58W-65W. An area of scattered moderate convection from 25N-30N between 41W-45W is being caused by upper-level diffluence to the NW of an upper-level anticyclone and also likely due to the presence of a high amplitude tropical wave passing just to the south. Some additional showers are seen within 150 nm of a line extending from 25N57W to 28N53W to 31N49W due to low-level troughing and upper- level diffluence in the area. Surface ridging and fair weather cover E Atlantic north of 20N and east of 40W. Tropical Storm Humberto, near 26.3N 76.0W at 5 AM EDT, is moving NW at 6 kt. Humberto will gradually intensify as it moves to near 29.0N 77.9W Sunday afternoon, before strengthening to a hurricane near 29.8N 77.4W W Monday morning. Humberto is then forecast to turn east to near 31N74.5W by Tuesday morning. Farther south, long long period NE swell will reach the waters northeast of the Leeward Islands early next week. $$ Hagen