000 AXNT20 KNHC 041730 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 130 PM EDT Thu Jul 4 2019 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. ...TROPICAL WAVES... A tropical wave has an axis along 34W from 03N-18N, moving W around 15 kt. A cluster of moderate convection is observed behind the wave axis, and where the wave meets the monsoon trough. This convective activity covers from 05N-10N between 30W-34W. The wave shows up well in model diagnostics and the TPW product. Some of the usual summertime African dust surrounds the wave based on GOES-R RGB Geocolor imagery and the Saharan Air Layer product from CIMSS. A well defined tropical wave is just E of the Lesser Antilles. Its axis is along 58W south of 18N to near the Guyana/Suriname border, moving W at 15-20 kt. The TPW product shows a large area of moisture related to this wave. Scattered moderate convection is noted on either side of the wave axis from 11N-15N between 54W- 61W. The Windward Islands are already reporting some shower activity with gusty winds in association with the wave, forecast to impact the Lesser Antilles the rest of today, and Puerto Rico and the UK/US Virgin Islands on Fri, bringing enhanced showers and thunderstorms with gusty winds. Moisture associated with this wave will likely reach Hispaniola late Fri into Sat. In addition, this wave is forecast to strengthen the trades across most of the basin through Sat as it passes across the forecast area, then reach Central America Sun. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Guinea-Bissau near 12N16W to 08N25W to 06N37W. The ITCZ continues from 06N37W to 04N51W. Aside from the convection associated with the tropical waves, scattered moderate convection is seen within about 120 nm S of the monsoon trough between 18W-30W. GULF OF MEXICO... Deep-layered ridge prevails across the entire Gulf of Mexico. As of 1500 UTC, a surface high of 1018 mb is analyzed near the mouth of the Mississippi River. Under the influence of this system, mainly light to gentle winds prevail, with seas generally under 4 ft, with the exception of gentle to moderate southerly winds and seas on the 3 to 5 ft range over the NW and west-central Gulf. A surface trough extends from near Tampa Bay, FL across the SE Gulf into western Cuba. Scattered showers and tstms are associated with this trough, forecast to drift westward across the eastern half of the Gulf on Fri. No significant convective activity is noted elsewhere across the Gulf waters. Weak high pressure will continue to dominate the region through the upcoming weekend, resulting in gentle to moderate winds across the Gulf. A trough will develop over the Yucatan Peninsula during the afternoon and move westward into the Bay of Campeche each evening, bringing a brief period of fresh to locally strong winds to the S central Gulf. CARIBBEAN SEA... A tropical wave is just E of the Lesser Antilles. Please, sea Tropical Waves section for more details. The most recent scatterometer pass indicates fresh to strong trade winds across the south-central Caribbean, with seas to near 9 ft based on altimeter data. Moderate to fresh winds are noted elsewhere across the E and central Caribbean as well as over the waters E of the Lesser Antilles, with gentle to moderate winds across the NW Caribbean. The pressure gradient between the Bermuda high and the Colombian/Panamanian low will continue to support fresh to strong trade winds across the south-central Caribbean through the weekend. These winds are also forecast to be enhanced by the passage of the above mentioned tropical wave. Scattered showers and thunderstorms are developing S of Cuba. A diffluent pattern aloft between a ridge over the Gulf of Mexico and an upper-level low spinning over the central Caribbean is helping to induce this convective activity. Shallow moisture embedded in the trade wind flow is noted elsewhere due to the presence of Saharan dust. ATLANTIC OCEAN... A surface trough extends from 30N72W to 27N73W based on a recent ASCAT pass. Isolated showers prevail near the trough. The remainder of the Atlantic Ocean is under the influence of the Bermuda-Azores high, anchored by a 1028 mb high near 34N38W. This system extends a ridge westward towards the Bahamas and Florida. Moderate to fresh easterly winds are noted across the southern periphery of the ridge. Little change in this weather pattern is expected over the next several days. Fresh to strong winds are expected N of Hispaniola Fri and Sat as the aforementioned tropical wave moves through the central Caribbean. For additional information please visit http://www.hurricanes.gov/marine $$ GR