048 AXNT20 KNHC 280531 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 131 AM 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 0000 UTC surface analysis and satellite imagery through 0515 UTC. ...SPECIAL FEATURES... Satellite images, radar data, aircraft data, and surface observations all indicate that Kirk's center made landfall on St. Lucia around 0030 UTC. Now, the center of Kirk is moving into the eastern Caribbean Sea. Heavy rainfall and strong winds will continue to spread across portions of the Lesser Antilles overnight. Tropical Storm Kirk is centered near 13.8N 61.4W at 28/0300 UTC. It is moving toward the west or 260 degrees 10 knots. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 45 knots with gusts to 55 knots. This tropical cyclone 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 by Friday and Saturday. Currently, satellite imagery indicates a band of numerous moderate and isolated strong convection within 60 nm NW semicircle of center. Numerous moderate to isolated strong convection is also noted elsewhere from 11.5N- 15N between 56W- 61W. Gradual weakening is anticipated during the next couple of days while the system moves over the eastern Caribbean Sea. Kirk is forecast to become a tropical depression Friday night, and degenerate into a trough of low pressure by Saturday. 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. Satellite derived winds indicate that the powerful non-tropical low is producing storm-force winds that extend several hundred miles from the surface circulation center. Although, associated shower activity remains rather limited, Leslie, is still expected to again become a subtropical storm, or possibly a tropical storm, Friday or Saturday while it moves west-southwestward at about 10 mph over the north-central Atlantic. 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 approaching the W coast of Africa, and will likely be added to the 0600 UTC analysis/surface map. A cluster of moderate to isolated strong convection is related to the wave. A tropical wave extends from 17N30W to 05N31W moving W at 10 kt. The wave shows up well in the TPW product. A patch of moisture with embedded showers is noted near the northern end of the wave axis. A tropical wave extends from 17N41W to 05N42W moving W at 10 kt. The Total Precipitable Water (TPW) imagery shows a maximum E of the wave axis. Satellite imagery indicates scattered showers mainly behind the wave axis from 10N-13N between 35W and 40W. A tropical wave is in the Caribbean Sea along 79W from 20N southward. A pronounced 700 mb trough in the GFS analysis is noted with the wave, which also coincides with a north-south moisture maximum. The wave, along with the monsoon trough, is helping to induce some shower activity over the SW Caribbean. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Senegal near 13N16W to 07N20W to 06N29W. The ITCZ extends from 06N32W to 07N40W to 06N50W to near the coast of Guyana at 07N58W. Scattered moderate to isolated strong convection is from 03N to 08N between 15W and 24W. ...DISCUSSION... GULF OF MEXICO... A band of showers with embedded tstms is noted across the Gulf waters ahead of a stationary front extending from SE Louisiana to NE Mexico near 25N97W. Recent scatterometer data provide observations of mainly gentle easterly winds on either side of the front, forecast to weaken on Fri as high pressure builds across the Gulf. The high pressure located NE of the region will support gentle to moderate E to SE winds and seas less than 4 ft across most of the Gulf waters through Sun. A surface trough is analyzed over the Yucatan Peninsula. An area of showers and tstms is seen on the west side of the trough affecting mainly the W coast of the Yucatan Peninsula and the eastern part of the Bay of Campeche. A surface trough is forecast to develop each evening over the Yucatan Peninsula before pushing offshore into the SW Gulf each night. A surge of moderate to fresh winds will accompany the trough. CARIBBEAN SEA... Tropical Storm Kirk will bring strong winds and heavy rain over portions of the Lesser Antilles overnight. Please, see Special Features section for details. A tropical wave is moving across the Caribbean Sea. See Tropical Wave section for details. Recent scatterometer data indicate increasing winds of 20-30 kt over the eastern Caribbean ahead of Kirk, and mainly moderate to fresh winds across the remainder of the eastern and central Caribbean while gentle to moderate winds are noted over the NW Caribbean. 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 Fri through Sun, building seas to 10 or 11 ft. ATLANTIC OCEAN... A cold front enters the forecast region near 31N33W then continues SW to 25N40W to 22N57W where it becomes stationary to near 25N70W. The front is associated with Post-Tropical Cyclone Leslie, which is centered N of area near 37N45W with a central pressure of 983 mb. This system is moving W at 10 kt. Please, see Special Features Section for more details. Large swell generated by Leslie, currently a powerful non-tropical low pressure system with storm-force winds, is expected to spread east of 75W by tonight, reaching the Bahamas, the waters N of Hispaniola and the Atlantic Passages E of la Mona Passage by early Sat, and the north and central Florida later on Sat. A ridge extends from a 1022 mb high pressure located near 36N59W across the western Atlantic, reaching Florida and the Bahamas. Another ridge dominates the remainder of the Atlantic E of the aforementioned cold front. For additional information please visit http://www.hurricanes.gov/marine $$ GR