331 AXNT20 KNHC 210534 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 134 AM EDT Fri Sep 21 2018 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 0000 UTC surface analysis and satellite imagery through 0515 UTC. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 25W/26W from 20N southward. Isolated moderate rainshowers are from 10N to 20N between 20W and 30W. An Atlantic Ocean tropical wave is along 48W/50W from 16N southward. Widely scattered moderate to isolated strong rainshowers are from 10N to 13N between 48W and 51W. Dry middle level air and strong upper level winds are expected to hinder any development of this disturbance while it moves toward the WNW. A Caribbean Sea tropical wave is along 72W/73W, moving across Hispaniola. Scattered moderate to isolated strong rainshowers are within 120 nm to the south of Hispaniola between 70W and 73W. Isolated moderate rainshowers are within 60 nm to the north of Hispaniola between 70W and 73W, and elsewhere from 16N to 20N between the Windward Passage and 81W. Satellite imagery has been showing Saharan dust to the east of the wave from 12N to 24N between 57W and 67W. Puerto Rico and the Virgin Islands have been reporting hazy conditions. Strong wind gusts are possible near the rainshowers that are associated with this wave through Friday as it moves westward through the central Caribbean Sea. The wave is expected to increase the likelihood of precipitation across Hispaniola, Cuba, and Jamaica for the next 24 hours or so. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal border sections of Guinea and Sierra Leone near 09N13W to 05N20W. The ITCZ continues from 05N20W to 06N28W, to 05N38W, and 08N44W. Scattered to numerous strong rainshowers are inland and in the coastal sections of Africa from 04N to 13N between 13W and 18W. Isolated moderate rainshowers are elsewhere from 15N southward between Africa and 60W. ...DISCUSSION... GULF OF MEXICO... An upper level cyclonic circulation center is near 28N80W, moving from the Atlantic Ocean toward Florida. Upper level cyclonic wind flow covers Florida, the Gulf of Mexico, and the Atlantic Ocean from the Florida Straits to 32N between 75W and 85W. Isolated moderate rainshowers are in the area of upper level cyclonic wind flow. Other isolated moderate rainshowers are in the Atlantic Ocean from 25N to 30N between 70W and 75W. A cold front extends from 1006 mb low pressure center that is near 33N64W, to 30N66W 28N70W 28N74W, and 29N81W near the coast of Florida. Isolated moderate to locally strong rainshowers cover the area that is from 28N northward between 46W and 66W. High pressure building in the eastern U.S.A. will support gentle to moderate E to SE winds, and sea heights ranging from 1 foot to 4 feet, across the basin through Sunday. It is possible that a surface trough, that will be moving westward across the southwestern corner of the Gulf of Mexico, may produce locally fresh winds through Saturday. CARIBBEAN SEA... Broad upper level cyclonic wind flow, with a trough, covers the Caribbean Sea from Hispaniola westward. Isolated moderate rainshowers are in the area of upper level cyclonic wind flow. The monsoon trough is along 08N/09N from 75W in Colombia beyond southern Costa Rica. Isolated moderate to locally strong rainshowers are from 13N southward from 78W westward. The Hispaniola tropical wave will move westward into Central America through Sunday. Gusty winds are possible near rainshowers associated with this wave. High pressure building westward from the central Atlantic Ocean into the Bahamas will support moderate to fresh trade winds and building seas through Friday. The wind speeds will diminish across most of the basin during the upcoming weekend. ATLANTIC OCEAN... An upper level cyclonic circulation center is near 28N80W, moving from the Atlantic Ocean toward Florida. Upper level cyclonic wind flow covers Florida, the Gulf of Mexico, and the Atlantic Ocean from the Florida Straits to 32N between 75W and 85W. Isolated moderate rainshowers are in the area of upper level cyclonic wind flow. Other isolated moderate rainshowers are in the Atlantic Ocean from 25N to 30N between 70W and 75W. A cold front extends from 1006 mb low pressure center that is near 33N64W, to 30N66W 28N70W 28N74W, and 29N81W near the coast of Florida. Isolated moderate to locally strong rainshowers cover the area that is from 28N northward between 46W and 66W. Dry air, that is associated with a weakening frontal system, and strong upper level winds, are expected to inhibit any significant development during the next couple of days. It is possible that conditions may become a bit more conducive for the 1006 mb low pressure center to acquire some tropical characteristics, gradually, early next week, while the system moves southward on Sunday, and then drifts westward to the southwest of Bermuda on Monday. A surface trough is along 33W/35W, from 24N to 32N. A 1018 mb low pressure center is along the trough near 30N. The 1018 mb low pressure center is the remnant of Joyce. Rainshowers are possible from 24N northward between 30W and 37W. An upper level trough extends from a 31N24W cyclonic circulation center, to a second upper level cyclonic circulation center that is near 28N40W, to 21N47W, to a third upper level cyclonic circulation center that is near 14N52W, to 14N60W. Isolated moderate rainshowers are within 180 nm on either side of the line that runs from 33N19W to 30N30W to 27N40W, and within 600 nm on either side of the line that runs from 27N40W to 17N47W. The current Bermuda-to-29N81W cold front will reach 27N on Friday, and then dissipate through Saturday. The low pressure center that is associated with the front will drift southward through Saturday, and then it will move northwestward early next week. NE swell will affect the waters E of the Bahamas through early next week. For additional information please visit http://www.hurricanes.gov/marine $$ MT