420 AXNT20 KNHC 121205 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 AM EDT Sun Aug 12 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 0600 UTC surface analysis and satellite imagery through 1100 UTC. ...SPECIAL FEATURE... GALE-FORCE WINDS NEAR THE COAST OF COLOMBIA AND IN THE GULF OF VENEZUELA... NE-to-E GALE-FORCE WINDS are being experienced from 11N to 13N between 70W and 76W, including in the Gulf of Venezuela. Expect sea heights to range from 9 feet to 13 feet, in the Caribbean Sea but not in the Gulf of Venezuela. Expect the GALE-FORCE wind conditions to continue for the next 12 hours or so, before slowing down to less than gale-force. GALE-FORCE wind conditions will start again Monday morning in the same areas, and last for 12 hours or so, ending during the early afternoon hours. Please read the High Seas Forecast, that is listed under the WMO/AFOS headers, as FZNT02 KNHC/MIAHSFAT2, for more details. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 16W/17W from 19N southward. Widely scattered moderate to isolated strong rainshowers are from 04N to 11N between land and 20W. It is easily possible that some of this precipitation also is related to the monsoon trough. An Atlantic Ocean tropical wave is along 37W/38W from 21N southward. Isolated moderate rainshowers are from 02N to 17N between 34W and 42W. It is easily possible that some of this precipitation also is related to the monsoon trough. An Atlantic Ocean tropical wave is along 49W/50W from 21N southward. Scattered moderate to isolated strong rainshowers are from 08N to 10N between 48W and 56W. Isolated moderate to locally strong rainshowers are elsewhere from 06N to 10N between 44W and 60W. It is easily possible that some of this precipitation also is related to the monsoon trough. A Caribbean Sea tropical wave is along 67W/68W from 21N southward. Isolated moderate to locally strong rainshowers are from 14N in the Caribbean Sea to 24N in the Atlantic Ocean between 66W and 72W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Senegal near 15N17W, to 12N37W, and 08N46W. The ITCZ is along 10N40W 08N45W 08N48W. Precipitation: isolated moderate to locally strong rainshowers are from 04N to 10N between 20W and 34W. Other broken to overcast multilayered clouds and possible rainshowers are elsewhere, away from the precipitation that is attributed to the tropical waves, from 10N southward from 40W eastward. ...DISCUSSION... GULF OF MEXICO... A surface ridge prevails across the basin, anchored by a 1018 mb high centered near 27N87W. With this, a gentle to moderate anticyclonic flow prevails across the area. To the southwest, a surface trough extends over the Bay of Campeche from 22N94W to 19N94W. Abundant cloudiness and scattered showers prevail across the west Gulf mainly west of 93W. An area of upper level diffluence prevails across the southeast Gulf waters enhancing scattered showers currently affecting the Florida Straits and Keys. A nocturnal trough moving off the Yucatan peninsula will induce a surge of fresh to strong NE to E winds in the Bay of Campeche each night. Otherwise, high pressure ridging will prevail across the area, supporting moderate to locally fresh SE winds over the west-central and NW Gulf most of the forecast period. CARIBBEAN SEA... A Gale Warning is in effect for the south-central Caribbean. Refer to the section above for details. An upper-level low is centered near 18N75W. This feature is enhancing convection across the northwest Caribbean waters mainly north of 20W and west of 74W. A tropical wave extends its axis along 66W. For more information, refer to the section above. The monsoon trough extends along 10N between 76W-82W. Scattered showers are noted across Panama and Costa Rica due to this. High pressure, that is to the north of the area, will support fresh to strong winds in the south central Caribbean Sea through Tuesday. It is possible that sustained wind speeds may reach gale force along the coast of Colombia and in the Gulf of Venezuela from tonight into Monday morning. The winds and seas in the Caribbean Sea will subside during the middle of the week, as the surface ridge that is in the western Atlantic Ocean weakens slightly. ATLANTIC OCEAN... An upper level low is centered over the northwest Caribbean near 18N75W. This feature is also enhancing convection across the west Atlantic, mainly over the Bahamas. Two tropical waves are moving across the basin. Refer to the section above for details. The remainder of the basin is under the influence of a surface ridge, anchored by a 1026 mb high centered near 29N54W and a 1030 mb high near 35N35W. The current surface ridge will remain in place during the next several days. The ridge will help to maintain gentle to moderate anticyclonic wind flow N of 23N, and mainly moderate easterly wind flow will prevail S of 23N. This scenario will support fresh to locally strong winds along the N coast of Hispaniola and the approaches to the Windward Passage during the evening and nighttime hours. For additional information please visit http://www.hurricanes.gov/marine $$ MT