000 AXNT20 KNHC 201736 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1236 PM EST Mon Feb 20 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the Atlantic Ocean through Liberia and extends to 04N14W. The ITCZ continues from this point to 02N22W 00N30W to 01S40W to 01N50W. Scattered moderate to isolated strong convection is noted from the Equator to 04N between 20W and 29W. Similar convection is along the Equator between 30W-40W. ...DISCUSSION... GULF OF MEXICO... The pressure gradient between a ridge across Florida and the eastern Gulf and a frontal trough across the NW Gulf and NE Mexico is supporting fresh to strong SE-S winds across the NW Gulf and moderate to fresh southerly winds elsewhere across the west and central Gulf. The most recent scatterometer data and buoys observations confirmed the presence of these winds. Mosaic Doppler radar from the SE U.S. along with lightning data reveals a band of showers and thunderstorms in association with this trough. Winds will continue to increase later today across the western Gulf as the pressure gradient tightens. The frontal trough and associated band of showers and thunderstorms will move eastward reaching from SE Louisiana to the central Bay of Campeche by early Tuesday morning, and from the Florida Panhandle to the Yucatan peninsula by Tue night. A weak low is forecast to form over the NE Gulf along the trough axis Tuesday night into Wednesday. This weather pattern is currently associated with an unusually sharp mid-upper level trough crossing central Texas and Mexico. Then, a cut-off low is forecast to develop at the mid- levels near the Texas/Louisiana border on Tuesday, with this low tracking slowly eastward into the NE part of the Gulf on Wednesday. This system is forecast to move across south Florida Wednesday night into Thursday producing unsettled weather conditions. CARIBBEAN SEA... High pressure centered over the SE CONUS extends a ridge across Florida into Cuba and the NW Caribbean. A weakening cold front is clipping the north-central coast of Cuba with the potential of few passing showers the rest of today. Moisture associated with this front will reach the northern coast of Hispaniola and eastern Cuba by this evening, producing some shower activity. Shallow moisture, embedded in the trade wind flow, will move across the remainder of the basin producing isolated to scattered passing showers. The high pressure centered north of area combined with Colombian/Panamaniam low will support fresh to strong winds near the coast of Colombia and in the Gulf of Honduras during the overnight and morning hours through Tuesday. The frontal trough forecast to move across the Gulf of Mexico will reach western Cuba and the NW Caribbean by Wedenesday morning with a band of showers and thunderstorms. This trough is forecast to extends from Matanzas Cuba to NE Honduras by Wednesday evening. Fresh to locally strong NW winds are expected behind the frontal trough. Gentle to moderate trades will persist elsewhere through Friday. In addition, the aforementioned cut-off low is forecast to also affect western Cuba on Wednesday, increasing the likelihood of showers and thunderstorms. In the upper levels, an anticyclone centered south of Costa Rica in the EPAC waters extens a ridge northward across Central America and the NW Caribbean into the eastern Gulf of Mexico. As a result, mainly a NW flow aloft dominates the western Caribbean while a westerly flow is noted over the eastern part of the basin. Strong subsidence is seen on water vapor imagery across much of the area. ...HISPANIOLA... A weakening frontal boundary is approaching from the north and will reach the coast this evening increasing the risk of showers. A drier air mass will follow the front on Tuesday. ATLANTIC OCEAN... Visible satellite imagery and recent scatterometer data indicate the presence of a 1011 mb low pressure located near 29N70W with the associated cold front extending SW across the Turks and Caicos Islands into the north-central coast of Cuba. A band of cloudiness with embedded showers is associated with the front. Lightning data indicate very active weather within this band north of 22N. Fresh to strong southerly winds are ahead of the front. Mainly fresh northerly winds will follow the front. The low pressure is forecast to move SE across the forecast area reaching a position near 24N61W by early Tuesday morning as a new cold front moves south of 30N. This new cold front will reach the SE Bahamas by late Tuesday. A stationary front extends from 31N72W to 21N56W where it begins to dissipate. The remainder of the Atlantic is under the influence of a ridge, anchored by a 1035 mb high pressure located NE of the Azores. The pressure gradient between this high and a low pressure system over Africa is resulting in fresh to strong northerly winds between the Madeira and Canary Islands and the coast of Africa. Looking ahead, the low with the associated frontal trough forecast to move across the Gulf of Mexico and Florida is expected to enter the Atlantic waters Wednesday night, supporting strong to near gale force winds across the northern Bahamas and the waters E of Florida to about 74W- 75W. For additional information please visit http://www.hurricanes.gov/marine $$ GR