864 AXNT20 KNHC 270005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 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 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...Special Features... Tropical Storm Kirk is centered near 12.5N 55.0W at 2100 UTC, or about 230 nm E of Barbados or 300 nm ESE of Martinique, moving westward 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 cyclone's cloud pattern has become comma shape during the afternoon, with convection of the scattered moderate to strong type within 180 nm of the center in the SE quadrant. Scattered moderate convection is within 240 nm of the center in the NE quadrant. Scattered moderate isolated strong convection is elsewhere within 240 nm in the SE quadrant, and also within 30 nm of line from 11N55W to 11N57W. 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 within the Tropical Storm Warning area Thu afternoon. Kirk is expected to produce very heavy rain across the northern Windward and southern Leeward Islands Thu through much of Fri. 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. Post-Tropical Cyclone Leslie, located over the central Atlantic Ocean several hundred miles west-southwest of the Azores, has intensified into a potent non-tropical low with hurricane-force winds. The associated shower activity is becoming more organized, and the low is showing signs of taking on more subtropical characteristics. Latest satellite imagery shows a large shield rain with embedded scattered to numerous showers between 90 and 480 nm of the low in the NW quadrant. Post-Tropical Cyclone Leslie is expected to again become a subtropical storm, or possibly a tropical storm, on Thursday or Friday while it moves west- southwestward at about 10 mph over the north-central Atlantic. There is a high 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 25W from 03N to 18N, 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. The wave is void of deep convection, except for scattered showers and thunderstorms from 15N to 18N between 23W and 26W. A tropical wave has been added to the analysis along 35W between 03N to 15N moving westward at 10 to 15 kt. Model guidance shows the wave corresponds nicely with a 700 mb trough. Scattered showers and thunderstorms are within 60 nm either side of the wave from 08N to 12N. A tropical wave has its axis along 71W 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 are within 120 nm of the wave from 15N to 18N. ...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 scattered showers and thunderstorms over the northwestern Gulf north of about 26N and west of 89W. Scattered showers and thunderstorms are elsewhere west of 90W, and just inland and along the coast of Florida from Naples to 29N. 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 to the northeast of the region will support gentle to moderate east to southeast 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... Instability generated by the eastern Pacific monsoon trough that protrudes into the far southwestern Caribbean, along pretty decent upper-level ventilation continues to allow for scattered moderate convection in clusters to remain active over much of the southwestern Caribbean south of 13N and west of 77W. Scattered showers and isolated thunderstorms are over much of the northwestern Caribbean, and also south of 16N east of 70W. Stronger activity, in the form of scattered moderate isolated strong convection, is over the far southeastern Caribbean, including the vicinity of Trinidad and Tobago. Expect fresh to strong trade winds to continue over the south- central Caribbean through Thu. 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 strong cold front and an associated area of gale force winds extend southward from Post-Tropical Cyclone Leslie low, which is currently a gale center, over the central Atlantic well north of the area near 36N39W with a pressure of 978 mb. The cold front enters the forecast area near 31N34W and extends southwestward to 25N41W to 24N50W to 26N60W and to 28N65W. Scatterometer data from Wed afternoon showed and area of strong to near gale force south to southwest winds north of 27N east of the front. Satellite imagery shows scattered moderate convection along and within 30 nm east of the front from 26N to 28N. The front is forecast to become stationary from near 29N35W to 23N44W and to near 21N51W by Thu afternoon and dissipate by early Fri afternoon. The strong to near gale force winds are forecast to diminish to strong winds on Thu and continue through Fri. The post-tropical cyclone low, gale center, is forecast to again become a subtropical or tropical storm during the next couple of days. More details are described above under the Special Features section. Elsewhere, an upper-level anticyclone, in combination with a very moist low-level easterly flow, is enhancing isolated showers and thunderstorms over the southeastern 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 $$ Aguirre