000 AXNT20 KNHC 121052 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 552 AM EST Sun Nov 12 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 0600 UTC surface analysis and satellite imagery through 1045 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 13N16W to 12N20W. The Intertropical Convergence Zone axis extends from 12N20W to 10N35W to 08N45W to 08N49W. Scattered moderate convection and tstms are from 03N-14N between 21W-46W. A surface trough is west of the ITCZ extending from 11N48W to 06N51W supporting isolated showers from 04N-13N between 46W-56W. ...DISCUSSION... GULF OF MEXICO... Strong high pressure anchored over Maine extends SSW across the SE CONUS and then across the Gulf waters. A weakness in the ridge is analyzed as a surface trough from the coast of Mississippi near 30N88W to 25N91W, which is generating isolated showers within 75 nm either side of its axis. A tight pressure gradient between the strong ridge and lower pressure over the SW N Atlc and the W Caribbean supports fresh to locally strong ENE winds E of the surface trough, the Yucatan Channel and the Florida Straits. Moderate NE to E winds are elsewhere. Otherwise, water vapor imagery indicate broad upper troughing over the basin along with relatively dry air aloft, which is maintaining generally fair weather conditions. The surface trough will continue to move across the NW Gulf through this afternoon and then dissipates. Fresh to locally strong winds will prevail across the eastern half of the basin through Tuesday. CARIBBEAN SEA... Broad low pressure prevails across the western Caribbean. A surface trough extends from 18N83W to Costa Rica coastal waters near 10N83W. Water vapor imagery indicate the trough is supported aloft by a mid-level low stretching from the Windward Passage to the SW Caribbean. In addition, a favorable diffluent environment remains over the western and central Caribbean, which is supporting scattered showers and tstms within 75 nm E of the trough axis and from 15N-21N W of 80W. A middle-level low NE of the Mona Passage supports scattered showers and tstms that extends to the Passage and across portions of Puerto Rico. A strong pressure gradient between high pressure N of the area and the broad area of low pressure in the western half of the Caribbean supports fresh to strong winds in the NW Caribbean N of 18N W of 80W. The synoptic pattern aloft will continue in place through Monday as the upper level troughing over the Gulf of Mexico and SW North Atlc will be slow to weaken into early next week. Otherwise, moderate to occasional fresh trades E of 75W will persist. ...HISPANIOLA... Scattered showers and isolated tstms continue across the island this morning as a favorable middle to upper level diffluent environment prevails. Upper level troughing is expected to persist to the NW over the SE Gulf of Mexico and SW North Atlc through tonight with persistent convection expected across the island, adjacent coastal waters and much of the north-central Caribbean Sea. Potential hazards of localized flooding and life-threatening mud slides are possible, especially if stronger convection develops during peak daytime heating and instability today and Monday. ATLANTIC OCEAN... A stationary front extends across the SW North Atlc from 30N64W SW to 27N73W then to the Florida coast near 27N80W. A middle- level low NE of the Mona Passage supports scattered showers and tstms S of 22N between 63W-73W. To the east, a surface trough extends from 30N56W to 25N57W with widely scattered showers and isolated tstms within 210 nm E of its axis. The surface trough remains within the southern periphery of a surface ridge anchored by a 1034 mb high centered NE of the Azores. Finally, a 1016 mb low near 30N35W and associated surface trough interacting with an upper-level low continues to produce an elongated area of disorganized showers and thunderstorms N of the area. Environmental conditions are expected to be conducive for a non- tropical low to form during the next day or so. The system could gradually acquire some subtropical characteristics by the middle of next week while it moves slowly northeastward. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos