000 AXNT20 KNHC 191801 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 PM EDT WED OCT 19 2016 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... A non-tropical 1004 mb surface low is centered northeast of the Turks and Caicos near 25N69W with a surface trough extending from 28N63W through the low then across the Turks and Caicos through the Windward Passage to 19N76W. Clusters of scattered moderate to isolated strong convection are from 19N-28N between 54W-67W. Scattered showers and isolated thunderstorms are within 90/120 nm of a line from 26N70W to over the Bahama Islands near 23N75W. The heavy convection is to the east of the low/trough due to strong westerly winds aloft. The upper level winds are expected to become more conducive for development and there is a medium chance of sub-tropical or tropical formation in the next 48 hours as the low moves northwest through tonight, then north- northeast before merging with a cold front this weekend. Regardless of development, locally heavy rainfall is possible over Hispaniola, Puerto Rico, and portions of the northern Leeward Islands through tonight. Please see the Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... Tropical wave in the east Atlantic extends along 34W/35W from 7N- 14N moving west near 15 kt over the past 24 hours. Wave coincides with a 700 mb trough and is embedded within a high amplitude surge of moisture. Clusters of scattered moderate to isolated strong convection are from 7N-13N between 30W-37W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 14N17W then along 8N23W to 8N38W where the ITCZ begins and continues along 7N46W to South America near 5N53W. Scattered moderate to isolated strong convection is from 9N-10N between 27W-30W. Large clusters of scattered moderate convection are from 1N-8N between 18W-32W and from 7N-17N between 42W-46W. ...DISCUSSION... ...GULF OF MEXICO... A broad upper ridge dominates the Gulf this afternoon with an upper ridge axis extending from the east Bay of Campeche to an upper high along the coast of Florida near Apalachicola Bay continuing along the eastern seaboard to North Carolina. Strong subsidence and dry, stable air aloft dominates the Gulf east of 90W. A surface ridge extends over the north Gulf anchored by a series of 1021 mb highs over South Carolina, south Georgia, and north Alabama. The easterly surface flow through the Straits of Florida are generating scattered showers within 45 nm of 23N between 81W-87W. The southerly surface flow around the surface ridge is bringing isolated showers dotting the coastal waters of Louisiana and scattered showers within 45/60 nm of a line from 23N94W to 29N92W. A mid level trough is in the east Bay of Campeche supporting a surface trough that extends from 21N94W to the coast of south Mexico near 18N92W with scattered showers and possible isolated thunderstorms within 60 nm of the surface trough. The surface ridge will persist through tonight then will retreat east ahead of a cold front that will move into the northwest Gulf Thursday. The front will race east reaching from central Florida to the Yucatan peninsula by Friday night then pass through the Straits of Florida Saturday night. ...CARIBBEAN SEA... A broad upper ridge anchored over Honduras extends an upper ridge axis east along 15N69W then into the central Atlantic over the Leeward Islands. A deep layered trough over the west Atlantic extends a mid to low level trough over the northwest Caribbean. At the base of this low to mid level trough is a 1008 mb low centered off the coast of Nicaragua/Honduras near 16N83W. A surface trough extends at 19/1500 UTC from the low east along 15N80W to 17N76W with a second surface trough extending south from the low along 13N82W to Costa Rica near 10N83W. Scattered showers and isolated thunderstorms are north of 11N west of 76W to the above surface troughs. Scattered to numerous showers and scattered thunderstorms are north of 14N to over Hispaniola and Puerto Rico between 66W-75W. The low and surface troughs will persist through the end of the week. A cold front will move into the northwest Caribbean this weekend from the Gulf of Mexico. ...HISPANIOLA... The deep layered trough over the west Atlantic extends over the island generating isolated to scattered showers over the island of Hispaniola with possible isolated thunderstorms developing later this afternoon. This could give the island showers and possible thunderstorms through early Saturday. ...ATLANTIC OCEAN... A deep layered trough extends over the west Atlantic from 63W- 80W supporting the low and surface trough in the special features above. The upper ridge over the Caribbean extends into the central Atlantic from the Leeward Islands near 18N63W to 31N50W. This is providing difflunce aloft to enhance the activity associated with the special features low/trough. A deep layered trough over the north/central Atlantic is supporting a remnant stationary front that extends to 32N34W where a surface trough begins and continues along 29N41W to 23N48W. Isolated showers are possible within 120 nm west of the surface trough. A second weak surface trough is in the east Atlantic extending from 30N31W to 27N23W. The special features low in the west Atlantic will move northwest through late Thursday before exiting off the east-northeast this weekend. Fresh to near gale force winds will occur mainly on the northwest side of the low. A cold front will move into the west Atlantic this weekend. For additional information please visit http://www.hurricanes.gov/marine $$ PAW