000 AXNT20 KNHC 181804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 204 PM EDT Fri Aug 18 2017 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 Harvey is located near 13.1N 61.3W at 18/1500 UTC, or about 13 nm SSW of St. Vincent, moving west at 18 kt. Reported minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Harvey will move through the Windward Islands and into the eastern Caribbean Sea today and move into the central Caribbean Sea on Saturday. Harvey is expected to produce additional rainfall totals of 1 to 2 inches with locally higher amounts across parts of the Leeward and Windward Islands from Guadeloupe southward to Grenada. These additional rains could cause life-threatening flash floods and mudslides. Presently, scattered moderate to strong convection is from 10N-16N between 60W-66W, to include all islands south of Guadeloupe. See the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC, and the full Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details. A tropical wave extends from 23N49W to a 1010 mb low near 17N50W to 10N50W. Scattered moderate to isolated strong convection is from 16N-20N between 48W-53W. The system continues to show signs of organization. However, upper-level winds are becoming less favorable, and the chances for a tropical cyclone to form are diminishing. The low is expected to move west-northwestward at about 20 kt during the next few days, and interests in the northern Leeward Islands should monitor the progress of this disturbance. This system has a medium chance of becoming a tropical cyclone within the next two days. ...TROPICAL WAVES... A tropical wave is in the E Atlantic with axis extending from 20N32W to a 1011 mb near 13N33W to 07N33W. Isolated moderate convection is from 09N-18N between 27W-37W. This wave is in a very moist area based on TPW imagery and has a well pronounced 700 mb trough. Gradual development of this system is possible through the middle of next week while the wave moves WNW at 20 kt. This system has a low change of becoming a tropical cyclone within the next 48 hours. A tropical wave is in the central Caribbean with axis extending from the S Bahamas near 23N74W to 16N75W to N Colombia near 10N75W, moving W at 15-20 kt. This wave in a moist area based on SSMI TPW imagery and has a well pronounced 700 mb trough. Isolated moderate convection is within 180 nm of the wave axis. A tropical wave extends from the Bay of Campeche near 20N95W to the Eastern Pacific near 06N97W. This wave in a moist area based on SSMI TPW imagery. Isolated moderate convection is within 120 nm of the wave axis, N of 16N. Scattered moderate to isolated strong convection is within 120 nm of the wave axis over the Eastern Pacific. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 12N16W to 10N20W to 13N30W to a 1011 mb low near 13N33W to 08N40W. Besides the convection mentioned in the tropical wave and special features sections, scattered moderate convection is off the coast of W Africa from 09N-14N between 14W-20W. ...DISCUSSION... GULF OF MEXICO... A tropical wave is over the Bay of Campeche. See above. A 1018 mb high is centered over the north central Gulf of Mexico near 28N90W with mostly fair weather. 5-10 kt anticyclonic winds are noted around the high. Radar imagery shows scattered moderate convection over the NE Gulf and N Florida from 27N-31N between 81W-87W. Scattered showers are over the remainder of the E Gulf. In the upper levels, an upper level low is centered over W Cuba near 23N81W enhancing showers. A small upper level high is centered over the NW Gulf near 29N92W. Expect the surface high to remain quasi-stationary over the Gulf for the next 24 hours. Expect more airmass thunderstorms Saturday during maximum heating over Florida, W Cuba, S Mexico, and the Bay of Campeche. CARIBBEAN SEA... Tropical Storm Harvey is over the Windward Islands, and a tropical wave is over the central Caribbean. See above. The eastern extent of the Pacific monsoon trough is producing scattered moderate convection over the SW Caribbean, Costa Rica and Panama. Expect Harvey to move W to the central Caribbean with convection over the next 48 hours. Expect the tropical wave to move W to the W Caribbean over the next 48 hours. Also expect continued convection over the SW Caribbean. ...HISPANIOLA... Presently fair weather is over Hispaniola. Expect Harvey to approach E Hispaniola in 24 hours. ATLANTIC OCEAN... The Atlantic basin N of 20N is under the influence of the mid- Atlantic subtropical high near 32N39W with mostly fair weather. For the tropical Atlantic S of 20N, see the special features and tropical waves sections above. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa