797 AXNT20 KNHC 071800 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 200 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 1200 UTC surface analysis and satellite imagery through 1730 UTC. ...SPECIAL FEATURES... Tropical Storm Florence centered near 25.0N 51.8W at 07/1500 UTC or 750 nm NE of the Northern Leeward Islands moving W at 7 kt. Estimated minimum central pressure is 996 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate convection is noted from 23N-28N between 47W-53W. The latest NHC forecast calls for Florence to move northwestward through tonight before it turns toward to the west on Fri. It is forecast to weaken slightly today, then re-strengthen beginning this weekend, reaching minimal hurricane intensity early on Sat and continue to gradually intensify through Sunday. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC for more details. Potential Tropical Cyclone Eight is centered near 13.1N 17.8W at 07/1500 UTC or 400 nm ESE of the Southernmost Cabo Verde Islands moving W at 9 kt. Estimated minimum central pressure is 1004 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Scattered moderate convection is noted from 09N-16N and east of 27W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT3/WTNT33 KNHC for more details. Satellite data indicate that the circulation of a low pressure system located about 700 miles west of the Cabo Verde Islands is well defined. However, the associated shower and thunderstorm activity has not been sufficiently organized to designate the system as a tropical depression. Only a slight increase in organization would lead to the initiation of advisories on this system, possibly as early as later today or tonight. This low is expected to move slowly westward across the tropical Atlantic Ocean during the next several days.The chance of this system becoming a tropical cyclone during the next 48 hours is now in the high range. Please read the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more information. ...TROPICAL WAVES... A tropical wave has its axis along 88W south of 20N, moving westward at 10 to 15 kt. Scattered showers are noted within 90 nm on either side of the wave's axis. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the Special Features low and wave along 17N to the next 1007 mb low to 09N47W. The ITCZ begins from this point to 09N61W. Aside from the convection related to the Special Features' lows, scattered moderate convection prevails along the ITCZ. ...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... Please refer to the Tropical Waves section above for details regarding a tropical wave along 88W. 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 Florence, Potential T.C. Eight, and the tropical wave/low in the east Atlantic with a chance of tropical development. 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 $$ ERA