597 AXNT20 KNHC 080005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Fri Sep 7 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... Tropical Storm Florence is centered near 24.8N 52.5W at 2100 UTC or 710 nm NE of the northern Leeward Islands, moving W at 7 kt. Estimated minimum central pressure is 996 mb. Maximum sustained winds are 55 kt with gusts to 65 kt. Scattered moderate to strong convection is within 120 nm north of the center. Florence is expected to move west and intensify to a minimal hurricane by Sat. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Tropical Depression Eight is centered near 13.2N 18.6W at 2100 UTC or 270 nm ESE of the Cabo Verde Islands, moving W at 9 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained winds are 30 kt with gusts to 40 kt. Scattered moderate convection is noted within 90 nm of the center. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details. Tropical Depression Nine is centered near 13.6N 34.9W at 2100 UTC or 950 nm E of the Windward Islands, and stationary. Estimated minimum central pressure is 1007 mb. Maximum sustained winds are 30 kt with gusts to 40 kt. Scattered moderate convection is noted within 120 nm NW of the center. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details. ...TROPICAL WAVES... All previous tropical waves in the Atlantic have transitioned in tropical cyclones, namely Tropical Depression Eight and Tropical Depression Nine. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 13N17W through T.D. Eight and T.D. Nine to 09N48W. The ITCZ begins from this point to 09N61W. Aside from the convection related to the tropical depressions, scattered moderate convection is from 09N to 12N between 22W and 27W. ...PREVIOUS DISCUSSION... GULF OF MEXICO... Upper-level cyclonic flow is located over eastern Louisiana and southern Texas and strong northeast upper-level winds are over eastern Gulf of Mexico along the western periphery of the large upper low that is over the northwestern Bahamas. A moist and unstable atmosphere along with plenty available instability is allowing for scattered showers to be over much of the eastern Gulf waters mainly east of 87W. Expect for this activity to remain through at least tonight. Weak ridging from the Carolinas to the Texas coast will shift northward through Sat, supporting gentle to moderate easterly winds and modest seas into early next week. The exception will be fresh winds pulsing off west of the Yucatan peninsula, mainly during the late evenings through the next few days due to the thermal trough that will develop over the Yucatan Peninsula and move west over the Bay of Campeche. CARIBBEAN SEA... An upper-level trough axis stretches from western Cuba to northeastern Honduras. Associated cyclonic flow covers the western Caribbean west of a line from Hispaniola to Panama. Upper-level anticyclonic flow covers the eastern Caribbean as the culprit anticyclone remains anchored near 15N68W. At this time, scattered moderate convection is noted south of 16N between 75W-81W. A relatively weak surface ridge in the western Atlantic Ocean will maintain moderate to fresh trade winds in most of the region into Sun. Building high pressure over the eastern Gulf of Mexico will allow fresh to strong E to SE winds and building seas over portions of the NW Caribbean late Sun and Mon. ATLANTIC OCEAN... Please read the Special Features section above for details about T.S. Florence, T.D. Eight, and T.D. Nine. A large upper-level low centered over South Florida and the northwestern Bahamas extends a trough southwestward across west Cuba. The low continues progressing in a westward motion. Its associated upper-level cyclonic flow covers the Atlantic west of 66W, and northward to about 35N. A surface trough is analyzed from 31N79W to 24N80W. Another surface trough is analyzed from near 31N71W to 27N73W. Scattered showers prevail west of 74W while scattered to numerous moderate convection is noted north of 30N between 62W-75W. A weak pressure pattern will maintain gentle to moderate easterly winds across the western Atlantic area into early next week. Tropical Storm Florence is forecast by the latest NHC advisory to move across the northeastern NHC/TAFB offshore waters zones Mon through Tue of next week. Easterly swell, in advance of Florence, are forecast to propagate through the open waters east of the Bahamas beginning this upcoming weekend. For additional information please visit http://www.hurricanes.gov/marine $$ Mundell