567 AXNT20 KNHC 281741 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 141 PM EDT Fri Sep 28 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... T.S. Kirk is weakening over the eastern Caribbean Sea. At 28/1500 UTC, Tropical Storm Kirk is centered near 13.8N 63.6W or about 160 nm (295 km) WSW of Martinique. It is moving toward the west- northwest or 285 degrees at 11 knots. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 40 knots with gusts to 50 knots. Kirk is forecast to weaken to a tropical depression tonight, and then degenerate into a trough of low pressure on Saturday. On the forecast track, the center of Kirk or its remnants will move across the eastern and central Caribbean Sea over the next day or two. Kirk is expected to produce total rainfall of 4 to 6 inches across the northern Windward and southern Leeward Islands with isolated maximum totals up to 10 inches across Martinique and Dominica. These rains may produce life-threatening flash floods and mudslides. Across Saint Croix and eastern Puerto Rico, Kirk is expected to bring 2 to 4 inches with isolated maximum totals of 6 inches today and Saturday. Scattered moderate and isolated strong convection is observed within 180 nm in the eastern semicircle. Please read the latest NHC Forecast/Advisory under AWIPS/WMO Headers MIATCMAT2/WTNT22 KNHC for more details. Post-Tropical Cyclone Leslie is located over the central Atlantic Ocean, several hundred miles west of the Azores. Shower activity has gradually increased near the center of the cyclone since last night and Leslie is expected to once again become a subtropical storm later today or tomorrow. Earlier satellite data indicated that the powerful low is producing storm-force winds that extend several hundred miles from the center, and Leslie will likely continue producing strong winds and high seas over a large portion of the central Atlantic for the next few days regardless of when it completes its transition to a subtropical storm. Scattered moderate convection is observed within 180 nm of the center. For more information on this system, see High Seas Forecasts issued by the National Weather Service under AWIPS header NFDHSFAT1, and WMO header FZNT01 KWBC. ...TROPICAL WAVES... A tropical wave is near 19W from 03N-19N. Scattered moderate convection is within 180 nm east of the wave axis south of 07N. This system shows up well in the Total Precipitable Water animation, and also has a sharp trough at the surface as seen by the ASCAT scatterometer pass. A second tropical wave near 45W extends from 02N-17N moving W at 10-15 kt. The TPW imagery shows a maximum E of the wave axis and there is a trough in the GFS 700 mb analyses, but little signature is seen at the surface. No significant convection is currently associated with the wave. A tropical wave is moving across the Caribbean Sea, near 81W from 21N southward. A pronounced 700 mb trough in the GFS analysis is noted with the wave, but little signature of the wave is seen at the surface. The wave, along with the monsoon trough, is helping to induce scattered moderate and isolated strong convection within 180 nm of the wave axis south of 14N. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean near 14N17W and continues SW to near 05N30W. The ITCZ extends from 05N30W to 07N52W and becomes indistinct farther west. Scattered moderate and isolated strong convection is observed from 04N to 07N between 18W and 28W. ...DISCUSSION... GULF OF MEXICO... A stationary front is located in the extreme NW Gulf waters from the just offshore the Texas-Mexico border to Louisiana. A trough extends southward from the end of the front near the Texas-Mexico border to 19N95W. Scattered moderate convection is occurring within 120 nm of these boundaries. Currents winds across the Gulf are moderate breeze or weaker out of the east, as a weak ridge is in place over the SE United States. The frontal boundary should dissipate by Saturday with little change to the winds during the next couple of days. Seas will remain below 8 ft through Sunday. CARIBBEAN SEA... Tropical Storm Kirk will bring strong winds and heavy rain over portions of the Lesser Antilles during the day. Please, see Special Features section for details. A tropical wave is moving across the western Caribbean Sea. See Tropical Wave section for details. Recent scatterometer data indicate generally easterly moderate breeze or weaker winds ahead of Kirk, except for an outflow boundary enhancement of winds to 25 kt in the southwestern Caribbean Sea. As tropical cyclone Kirk weakens over the Caribbean Sea, expect mainly moderate to fresh winds through early next week. Large northerly swell associated with Post-Tropical Cyclone Leslie will affect the tropical Atlantic waters today through Sunday, building seas to 10 or 11 ft. ATLANTIC OCEAN... Two tropical waves are currently between the coast of Africa and the Lesser Antilles. A stationary front enters the forecast region near 31N40W then continues SW to 22N59W. From there the feature is a dissipating stationary front to 25N72W. The front is associated with Post-Tropical Cyclone Leslie, which is centered N of area near 37N46W with a central pressure of 992 mb. This system is moving W at 9 kt. Please, see Special Features Section for more details. Large swell generated by Post-Tropical Cyclone Leslie, currently a very large non-tropical low pressure system with gale-force winds, is expected to propagate across the waters east of 75W by tonight, reaching the Bahamas, the waters N of Hispaniola and the Atlantic Passages E of la Mona Passage by early Saturday, and the north and central coast of Florida later on Saturday. A ridge extends from a 1023 mb high pressure located near 33N64W across the western Atlantic reaching Florida. Another ridge dominates the remainder of the Atlantic E of the aforementioned cold front. For additional information please visit http://www.hurricanes.gov/marine $$ CL