000 AXNT20 KNHC 040536 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 136 AM EDT Fri May 4 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 0000 UTC surface analysis and satellite imagery through 0600 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 08N13W to 00N35W. The intertropical convergence zone continues from 00N35W to 00N50W. Scattered moderate convection is ongoing from 02S to 04N between 20W and 25W. ...DISCUSSION... GULF OF MEXICO... A ridge extends east to west from the western Atlantic along the northern Gulf coast to Texas. Strong peak winds reported by CMAN observations in the Florida Keys are evidence of fresh to strong easterly winds persisting across the Straits of Florida, between the ridge to the north, a weak trough over the far southeast Gulf, and a more developed trough to the east. Seas are likely reaching 8 ft in the Straits accordingly, reaching as far west as the approaches to the Yucatan Channel. Convergence of the fresh to strong easterly flow out of the Bahamas is supporting scattered showers across the Straits, as noted in regional radar. Fresh SE return flow and seas to 6 ft are noted over the far northwest Gulf, between the ridge and lower pressure over south Texas. A couple of platforms in the Texas coastal waters are report fog in the moist SE flow, but widespread fog or significant restriction to visibility are not anticipated overnight. Farther south, a thermal trough will develop over the northwest coast of Yucatan during the evening, and drift westward across the SW Gulf before dissipating later in the morning. A surge of fresh to occasionally strong NE to E winds will accompany this trough. This pattern will repeat each evening through the period. For the forecast, winds over the southeast Gulf will diminish and back more to the NE through early Sat ahead of the trough moving from the western Atlc across Florida. Scattered showers and thunderstorms will accompany the trough as it moves into the eastern Gulf early Sun before stalling and weakening. The ridge will weaken as well and high pressure will shift west through the lower Mississippi Valley, allowing moderate northerly flow and 2 to 4 ft seas through mid week. CARIBBEAN SEA... A surface trough is developing from north of Hispaniola into the north central Caribbean. E to SE winds will increase slightly from the Tropical North Atlantic through the central Caribbean as high pressure builds westward over the Atlantic in the wake of the trough. This is already starting to happen as winds off Colombia diminish slightly, as they increase through the Windward and Leeward Islands. Strong NE winds are also noted in the lee of Cuba on a recent scatterometer pass from 02 UTC. Scattered thunderstorms are popping up in the Windward Passage as well, on the southeast side of a prominent mid/upper low centered north of the area. Seas will build over tropical north Atlantic and the eastern Caribbean to 6 to 9 ft through Sun. This pattern will persist through Sun, then start to subside into early next week as the trough moves farther westward and the ridge weakens. Instability associated with the mid/upper level low will provide more thunderstorm potential to the north central Caribbean through late Sat. ATLANTIC OCEAN... The main weather maker remains a prominent cold-core, mid/upper level low centered over Cat Island in the central Bahamas. Divergence of the southeast side of this feature is supporting a broad area of scattered showers and thunderstorms over the southern Bahamas, Turks/Caicos Islands, and north of Hispaniola and Puerto Rico. This is also supporting the development of a amplifying surface trough extending from 27N68W through Haiti and into the north central Caribbean. Strong NE to E winds are ahead of the trough east and across the Bahamas, as noted in a 02 UTC scatterometer satellite pass, with seas in excess of 8 ft noted in a concurrent altimeter satellite pass. Moderate to fresh easterly winds are noted north of 27N, closer to the subtropical ridge axis. Buoy and scatterometer data also show strong SE winds off the Leeward Islands in the Atlantic, with buoys showing seas to 9 ft. This is related to ridging building in the wake of the trough. The trough will sharpen and elongate as it moves westward, eventually moving into Florida Sat. Strong to near gale force winds will accompany the trough, as well numerous showers and scattered thunderstorms across the Bahamas through Sat. Scattered thunderstorms are possible across the Bahamas and adjacent waters into Sun as the upper low slowly drifts south-southwestward. Winds and seas will start to diminish Sun through early next week as through lifts northward to off the northeast coast of Florida through Mon, and the ridge weakens, but hold in place along roughly 28N/29N. Farther east, the remainder of the Atlantic is under the influence of a 1029 mb high pressure located near the Azores. This system is producing moderate to fresh trade winds across the deep tropics, where seas are reaching 6 to 8 ft in NE to E swell. For additional information please visit http://www.hurricanes.gov/marine $$ Christensen