782 AXNT20 KNHC 140545 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 145 AM EDT Fri Sep 14 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 1115 UTC. ...SPECIAL FEATURES... Hurricane Florence centered near 34.1N 77.2W at 14/0600 UTC or 30 nm E of Wilmington North Carolina moving WNW at 5 kt. Estimated minimum central pressure is 954 mb. Maximum sustained wind speed is 80 kt with gusts to 100 kt. Scattered moderate to strong convection is from 32N-37N between 73W-80W. The present NW motion is forecast to continue into Friday. A turn toward the west-northwest and west at a slow forward speed is expected through Friday, followed by a slow west-southwestward motion Friday night and Saturday. On the forecast track, the center of Florence is expected to move inland across extreme southeastern North Carolina and extreme eastern South Carolina Friday and Saturday. Florence will then recurve across the western Carolinas and the central Appalachian Mountains early next week. Little change in strength is expected before Florence moves inland on Friday. More significant weakening is expected over the weekend and into early next week while Florence moves farther inland. The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. Public Advisories for Florence are issued under WMO header WTNT31 KNHC and under AWIPS header MIATCPAT1. Forecast/ Advisories for Florence are issued under WMO header WTNT21 KNHC and under AWIPS header MIATCMAT1. Tropical Storm Isaac is centered near 14.9N 64.4W at 14/0300 UTC or 170 nm S of St. Croix moving W at 14 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered moderate to isolated strong convection is from 13N-17N between 55W-65W. A westward motion with a decrease in forward speed is expected for the next few days. On the forecast track, Isaac will move over the eastern and central Caribbean Sea during the next few days. Isaac is forecast to gradually weaken over the next few days, and could degenerate into a tropical wave at any time. Public Advisories for Isaac are issued under WMO header WTNT34 KNHC and under AWIPS header MIATCPAT4. Forecast/ Advisories for Isaac are issued under WMO header WTNT24 KNHC and under AWIPS header MIATCMAT4. Tropical Storm Helene centered near 29.7N 36.2W at 14/0600 UTC or 710 nm SW of Lajes Air Base In The Azores moving N at 18 kt. Estimated minimum central pressure is 992 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate to isolated strong convection is from 21N-27N between 32W-40W. The cyclone is expected to accelerate and turn toward the northeast over the weekend. On this forecast track, Helene will be passing near or over the Azores late Saturday or Sunday. Public Advisories for Helene are issued under WMO header WTNT33 KNHC and under AWIPS header MIATCPAT3. Forecast/ Advisories for Helene are issued under WMO header WTNT23 KNHC and under AWIPS header MIATCMAT3. Tropical Storm Joyce is centered near 32.9N 44.4W at 14/0300 UTC or 900 nm WSW of the Azores moving SSW at 6 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Isolated moderate convection is from 31N- 37N between 37W-46W. Joyce is moving toward the south-southwest near 7 mph (11 km/h), and this general motion is expected to continue tonight. Joyce is forecast to gradually turn toward the northeast on Friday and then accelerate northeastward over the weekend. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC for more details. An Air Force reconnaissance plane investigating the disturbance in the western Gulf of Mexico found a broad and elongated area of low pressure with a few squalls. Isolated moderate convection is from 20N-30N between 90W-100W. Upper-level winds are conducive for development, and a tropical depression could still form before the system moves inland along the western Gulf coast on Friday. Another Air Force reconnaissance plane will investigate the system on Friday if necessary. Regardless of development, heavy rainfall and gusty winds are expected across portions of northeastern Mexico and Texas on Friday and Saturday. There is a medium chance for tropical cyclone formation within 48 hours. Please read the latest Tropical Weather Outlook under WMO header ABNT20 KNHC, and under the AWIPS header MIATWOAT for more details. ...TROPICAL WAVES... A tropical wave is along 26W, from 06N-20N, moving W at 10 kt. The wave is supported by well pronounced 700 mb troughing as depicted in the GFS model guidance. Isolated moderate convection is between 04N-10N between 22W-31W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from W Africa near 18N16W to 08N26W to 09N40W. The ITCZ continues from 09N40W to 10N50W to 14N57W. Aside from the convection associated with the tropical wave along 26W, scattered moderate convection is from 03N-08N between 11W-18W. ...DISCUSSION... GULF OF MEXICO... Please read the SPECIAL FEATURES section for details about an area of disturbed weather that is in the western Gulf of Mexico. An upper-level low is over the NE Gulf near 29N83W. Widely scattered moderate convection is over the far NE Gulf of Mexico and Florida. A dissipating stationary front is located along the Texas and SW Louisiana coasts with scattered showers and isolated moderate thunderstorms. CARIBBEAN SEA... Please read the SPECIAL FEATURES section for details about Tropical Storm Isaac. The eastern extent of the eastern Pacific monsoon trough passes through Costa Rica and Panama along 09N. Scattered moderate convection is S of 11N. An large upper level low is in the western Caribbean Sea near 18N80W. Isolated weak convection is between 13N-20N between 78W- 83W. An an upper level high is centered in the NE Caribbean Sea near 19N69W, producing a good amount of shear over T.S. Isaac. ATLANTIC OCEAN... Please read the SPECIAL FEATURES section, for details about Hurricane Florence, Tropical Storm Helene, and Subtropical Storm Joyce. No other significant features are noted in the Atlantic other than the features mentioned above. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa