000 AXNT20 KNHC 182345 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 645 PM EST FRI NOV 18 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 1800 UTC surface analysis and satellite imagery through 2330 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: A strong cold front will enter the northwest Gulf of Mexico tonight, move across the central Gulf on Saturday, then extend from the Straits of Florida to the SW Gulf near 21N95W to the central Bay of Campeche by early Sunday. Strong northwesterly winds are expected over the northern Gulf in the wake of the front with building seas to 8-9 ft. As a strong high pressure builds behind the front reaching eastern Mexico and the western Gulf, northerly gale force winds will begin by early Saturday just north of Tampico, and spread southward toward the area of Veracruz by late Saturday. Seas of 10-13 ft are expected within the area of gale force winds. Winds will diminish below gale force across the SW Gulf by Sunday. Please refer to the High Seas Forecast product under AWIPS/WMO headers HSFAT2/AXNT20 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 11N15W to 08N20W where it transitions into the ITCZ and continues through 09N36W to 07N58W. Scattered moderate convection is observed from 05N-11N between 18W-39W. ...DISCUSSION... ...GULF OF MEXICO... Gale-force winds will develop across the western Gulf on Saturday behind a cold front that will enter the northern Gulf tonight. Please refer to the Special Features section above for details. Dry and stable conditions prevail across the basin at this time as a surface ridge extends across the basin, anchored by a 1022 mb high centered over northern Florida near 29N82W. With this, a gentle to moderate anticyclonic flow prevails across the area. Expect through the next 24 hours for convection to develop across the northwest Gulf as the front approaches. This activity will move southeast with the front. ...CARIBBEAN SEA... A stationary front extends from the west Atlantic across Hispaniola into the central Caribbean from 18N72W to 14N83W. A diffluent flow aloft combines with the front to generate scattered moderate convection from 12N-19N between 77W-84W. A stationary 1006 mb surface low continues north of Costa Rica near 11N82W enhancing convection from 10N-12N and west of 80W. Upper-level winds have become less conducive for tropical cyclone formation in this area, and during the next couple of days any development should be slow to occur. After that time, environmental conditions are expected to be marginally conducive for gradual development, and a tropical depression could form early next week while the low moves slowly and erratically. To the east, a surface trough extends across the Mona Passage from 20N65W to 16N68W. Diffluence aloft is also enhancing convection in this area affecting Puerto Rico, the Virgin Islands and adjacent waters north of 15N between 64W-69W. Scatterometer data depicts fresh to strong northeasterly behind the front including the Windward Passage and the lee of Cuba. An area of fresh winds are also prevailing near the surface low in the southern Caribbean. Expect for the front to remain nearly stationary over Hispaniola over the weekend while gradually dissipating. The surface trough over the Mona Passage will drift westward and combined with the stationary front, will keep the north-central Caribbean very unstable mainly for the area of Puerto Rico and Hispaniola. A cold front will move into the west Caribbean on Sunday followed by fresh to strong northeast winds. ...HISPANIOLA... A stationary front extends across the island from 20N70W to 18N72W. Atmospheric conditions across the island are forecast to remain very moist and unstable during the weekend with the potential to produce scattered to numerous showers and thunderstorms as the front persists and combines with a diffluent flow aloft. ...ATLANTIC OCEAN... A broad area of high pressure prevails across the west Atlantic mainly west of 68W. To the east, a 996 mb surface low extends its frontal boundary south analyzed as a cold front from 31N59W to 21N64W then as a stationary front from that point into the Caribbean basin. No significant convection is related to the cold front at this time. Scattered moderate convection is observed east of the stationary front affecting the waters north of Puerto Rico south of 21N between 64W-67W. An upper-level low is reflected at the surface as a trough that extends from 26N34W to 23N35W. Another surface trough was analyzed from 16N29W to 13N32W. Isolated showers are observed along this feature. The remainder of the basin is under the influence of a surface ridge, anchored by a stationary 1028 mb high centered near 39N36W. During the next 24 hours, the frontal system between 60W-70W will become stationary begin to weaken. Expect for a strong cold front to move off the northeast Florida coast on Saturday night and extend from 31N68W to northern Bahamas on Sunday. Fresh to strong northwesterly winds will follow the front Saturday night and early Sunday. For additional information please visit http://www.hurricanes.gov/marine $$ ERA