000 AXNT20 KNHC 191737 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1237 PM EST SAT NOV 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... An area of low pressure of 1006 mb remains over the SW Caribbean located near 11N81.5W. Showers and thunderstorms have increased and become better organized this morning in association with this system. A cluster of moderate to strong convection is noted within 90 nm SE and 30 nm NW semicircles of low center. Scattered moderate isolated strong convection is observed elsewhere from 10N to 13N between 79W and 83W. In addition, scatterometer data and surface observations indicate that the circulation has become a little better defined, with fresh to strong winds, mainly in the northern semicircle of the low due to the pressure gradient between the low and high pressure to the N. Although environmental conditions are only marginally conducive for additional development, only a small increase in the organization of the low could result in the formation of a tropical depression. This system is expected to move slowly and erratically during the next few days. The latest Tropical Weather Outlook gives this system a medium change of tropical cyclone formation during the next 48 hours. Gulf of Mexico Gale Warning: A strong cold front is moving across the Gulf waters. At 1500 UTC, the front extends from the Florida Panhandle to 25N95W to near Poza Rica, Mexico. Frequent gusts to gale force are noted behind the front based on surface and buoy observations. Strong northerly winds are expected over the northern Gulf in the wake of the front today with building seas up to 9-10 ft. A sharp ridge is currently building across eastern Mexico and the western Gulf anchored by a 1039 mb high pressure over NE Mexico. This will support northerly gale force winds near Tampico early this afternoon, and spreading southward toward the area of Veracruz by this evening. Computer model indicates building seas of 11-12 ft within the area of gale force winds. The front is forecast to cross the basin today, reaching from the Straits of Florida to the SW Gulf by Sunday morning. Winds are expected to diminish below gale force across the SW Gulf on 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 7N12W to 6N15W where it transitions to the ITCZ and continues along 5N25W to 9N36W to 7N50W to the coast of Guyana near 7N59W. Scattered moderate convection is within 90 nm S of the ITCZ axis between 35W and 39W. No significant convection elsewhere. ...DISCUSSION... ...GULF OF MEXICO... A gale warning remains in effect for the west-central and SW Gulf in association with a strong cold front currently moving across the area. Please, see Special Features section for details. The remainder of the Gulf region is under the influence of a ridge. The pressure gradient between the ridge and a developing low pressure area over the SW Caribbean is producing an increase in winds over the SE Gulf, where scatterometer data indicate fresh NE winds. Doppler Radar shows isolated showers moving westward across the Straits of Florida. The cold front is forecast to move across South Florida on Sunday morning. The frontal passage will be mainly dry, followed by gusty northerly wind and chilly temperatures on Monday morning. ...CARIBBEAN SEA... A stationary front extends from the central Atlantic across Hispaniola into the Caribbean Sea to the coast of Nicaragua near 14N83W. Fresh to strong NE winds are noted per scatterometer data behind the front, including the Windward Passage and in the lee of Cuba, particularly N of 18N E of 85W. Winds have also increased S of Dominican Republic. Scattered showers and thunderstorms are noted along the frontal boundary, mainly from 15N-17N between 72W-75W, and within about 30 nm either side of the front between 77W-79W. Additional shower and thunderstorm activity is noted between the front and the developing low pressure over the SW Caribbean, especially W of 80W to the coast of Nicaragua. Please, see Special Features section for details on the evolution of the low pressure. The front is forecast to remain nearly stationary over Hispaniola on Sunday while gradually dissipate over the Caribbean Sea. A diffluent pattern aloft is also helping to induce some shower activity with isolated thunderstorm across the east and central Caribbean. A ridge from the Atlantic and low-topped trade wind showers are expected over the Lesser Antilles. A cold front will move into the NW Caribbean on Sunday followed by fresh to strong NE winds. ...HISPANIOLA... Atmospheric conditions across Hispaniola remain very moist and unstable due to the presence of a frontal boundary. This weather pattern will persist on Sunday with additional showers and thunderstorms and the potential for locally heavy rain and flash flooding. ...ATLANTIC OCEAN... A cold front, associated with an occluded low pressure system, enters the forecast region near 31N55W, then continues SW to near 23N61W where it becomes stationary, extending over Hispaniola and the Caribbean Sea. A recent Ascat pass indicates fresh to strong southerly winds just ahead of the front. Scattered showers are also ahead of the front, but mainly N of 24N. The front will remain nearly stationary through Monday while gradually weakening. At the same time, another cold front will move off the NE Florida coast tonight. This front will extend from 31N68W to the Northern Bahamas on Sunday, and from 27N65W to the Southern Bahamas on Monday. Fresh to strong NW winds will follow the second front tonight and early Sunday. A ridge dominates the remainder of the east and central Atlantic anchored by a 1029 mb high pressure located W of the Azores near 38N36W. A surface trough, reflection of an upper-level low, persists across the Atlantic and stretches from 26N36W to 22N38W. Some shower activity persists in association with this trough. Fresh to locally strong easterly winds are between the trough and high pressure to the N, particularly N of 27N. 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