327 AXNT20 KNHC 261756 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 155 PM EDT Wed Sep 26 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 1715 UTC. ...Special Features... Tropical Storm Kirk is centered near 12.5N 55.0W at 1800 UTC, or about 265 nm E of Barbados or 375 nm ESE of Martinique, moving west at 16 kt. The estimated minimum central pressure is 998 mb. The maximum sustained wind speed is 50 kt with gusts to 60 kt. The deep convection associated with this tropical storm extends outward from the center up to 180 nm in the northeast semicircle and 60 nm in the southwest quadrant. The convection has continued to look impressive and is gradually becoming more symmetrical during the last several hours. The latest NHC advisory has Kirk moving in a westward to west-northwestward motion through Fri night. On this track, Kirk is expected to move over the Lesser Antilles Thursday night. It will move into the eastern Caribbean Sea by Fri morning. Little change in strength is forecast until Kirk crosses the Lesser Antilles, followed by weakening over the eastern Caribbean Sea. Kirk is expected to produce very heavy rain across the northern Windward and southern Leeward Islands Thursday through much of Friday. These rains may produce life- threatening flash floods and mudslides, especially across Martinique and Dominica. See latest NHC Forecast/Advisory under AWIPS/WMO Headers MIATCMAT2/WTNT22 KNHC for more details. A strong cold front and an associated area of gale force winds extend southward from Post-Tropical Cyclone Leslie over the central Atlantic. The cold front enters the forecast area near 31N37W and extends SW and W to 27N40W to 26N49W to 27N58 where it becomes a dissipating cold front. The dissipating cold front extends to 29N64W. The latest ASCAT data show gales are currently occurring north of 29N and east of 37W, along the front and extending to 90 nm east of the front to 34.5W. Winds in this area are forecast to diminish below gale force later this afternoon. However, winds will remain around 30 kt in the area during the next couple of days. Scattered moderate convection is along and within 90 nm ahead of the front for the portion of the front that's east of 39W. Meanwhile, Post-Tropical Cyclone Leslie, centered several hundred nm west-southwest of the Azores, is producing gale force winds. Scattered moderate convection is from 34N-38N between 37W-42W. Leslie is expected to reacquire subtropical or tropical characteristics on Thu or Fri while the cyclone meanders over the north-central Atlantic. There is a medium chance of this system becoming a tropical or subtropical cyclone during the next 48 hours. For more information on this system, see High Seas Forecasts issued by the National Weather Service. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 24/25W from 03N to 17N, moving westward at 10 to 15 kt. Model guidance depicts a broad 700 mb trough a few degrees ahead of this wave. Total precipitable water (TPW) imagery clearly indicates a maximum in TPW associated with this tropical wave. Scattered showers and thunderstorms are located north of 13N between the wave axis and 19W. A tropical wave has been added to the analysis along 35W between 03N-13N moving west around 10-15 kt. Model guidance shows the wave corresponds nicely with a 700 mb trough. Scattered showers and thunderstorms are located from 03N-09N between 30W-38W. A tropical wave has its axis along 70W south of 19N, moving westward at 15 kt. The Total Precipitable Water (TPW) satellite animation shows a broad pool of moisture between 65W-71W. Scattered showers and thunderstorms extend from 12N-15N east of the wave axis to 64W. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends off the coast of Africa over Senegal at 14N17W and continues to 09N25W to 07N32W, where the ITCZ begins and continues to 06N46W. Outside of the convection mentioned with the two tropical waves, scattered moderate convection is noted within 120 nm north and 90 nm south of the ITCZ between 38W-44W. ...DISCUSSION... GULF OF MEXICO... Upper-level diffluence over the north-central Gulf Coast is enhancing showers and thunderstorms over southern Louisiana and the Gulf waters north of 27.5N between 90W-94W. This enhanced activity has generally been moving slowly westward. A thermal trough is analyzed over the central Bay of Campeche. Scattered showers and thunderstorms are near the coast of Mexico between Veracruz and Tuxpan and over the Gulf south of 21N and west of 95W. High pressure NE of the region will support gentle to moderate E to SE winds and seas less than 4 ft across most of the region through Sun. The only exception is locally fresh winds each night associated with a trough moving over the eastern Bay of Campeche. CARIBBEAN SEA... Convection associated with Tropical Storm Kirk and the tropical wave in the east-central Caribbean is described above in the Special Features and Tropical Waves Sections. The forecast for the eastern half of the Caribbean is also described above. Elsewhere, instability generated by the eastern Pacific monsoon trough that protrudes into the far southwestern Caribbean, along with upper-level divergence in the area is generating an area containing numerous moderate and isolated strong convection from Panama northward to 12N between 77W-84W. In the northwest Caribbean, upper-level anticyclonic turning is helping to generate scattered moderate convection from 16N-19N between 83W and the coast of Belize. Expect fresh to strong trade winds to continue over the south- central Caribbean through Thursday. ATLANTIC OCEAN... Tropical Storm Kirk and two tropical waves between Africa and the Lesser Antilles are described above in the Special Features and Tropical Waves sections. A cold front and associated gale force winds extending southward from Post-Tropical Cyclone Leslie has also been described above in the Special Features section. Elsewhere, an upper-level anticyclone is enhancing isolated showers and thunderstorms over the southeast and central Bahamas, northern Cuba and the Florida Straits. A high pressure ridge extends over the northwest Bahamas and the waters east of Florida, creating fair weather north of 25N west of 75W. For additional information please visit http://www.hurricanes.gov/marine $$ Hagen