000 AXNT20 KNHC 301754 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Wed Jun 30 2021 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1710 UTC. ...SPECIAL FEATURES... Broad low pressure of 1008 mb located where a tropical wave intersects the monsoon trough near 09N42W, about midway between the African coast and the Lesser Antilles is producing scattered moderate to isolated strong convection from 06N to 10N between 40W and 48W. Peak winds are near 30 kt and highest seas around 10 ft. Environmental conditions appear generally favorable for development, and a tropical depression is likely to form during the next few days while the system moves WNW at 15 to 20 kt. Interests in the Windward and Leeward Islands should closely monitor this system as it will likely be moving through that region on Friday. Please read the latest Tropical Weather Outlook at www.hurricanes.gov, for more information. ...TROPICAL WAVES... An Atlantic tropical wave is along 27W from 12N southward and moving W near 15 kt. Scattered moderate convection is seen from the Equator to 08N between 21W and 33W. The wave has a weak trough noted at the surface. Another Atlantic tropical wave is near 41W from 17N southward and moving W at 15 to 20 kt. Please see Special Features section above for more information on convection and the potential for this wave to develop into a tropical cyclone. A third Atlantic tropical wave is along 58W from 18N southward and moving W at 20 to 25 kt. Scattered moderate to isolated strong convection is found from 10N to 18N between 58W and 65W over the Lesser Antilles. The tropical wave displays a sharp trough at the surface. Significant development of this system is unlikely while it moves quickly west. This wave will pass through the Lesser Antilles this evening and then across the eastern and central Caribbean Sea over the next few days. Regardless of development, this system could bring locally heavy rainfall to the Lesser Antilles, especially the Windward Islands during the next couple of days. A Caribbean tropical wave is over eastern Cuba and the central Caribbean and moving W near 10 kt. Scattered showers and isolated thunderstorms are present near the Windward Passage. The tropical wave is only identifiable from GFS- and ECMWF-based 700 mb trough diagnositics. Another Caribbean tropical wave is near the western end of Cuba and the western Caribbean, moving W at 5 to 10 kt. Scattered moderate to isolated strong convection is noted near the Yucatan Channel and basin. The tropical wave is only identifiable from GFS- and ECMWF-based 700 mb trough diagnositics. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 17N16W to 08N29W to a low pressure near 08N41W to 06N44W. The ITCZ then continues from 06N47W to near the Suriname/Brazil border. All convection in the vicinity of these features is related to tropical waves described in the sections above. GULF OF MEXICO... An upper-level trough curves S from the Florida panhandle to near the Yucatan Peninsula. Scattered showers and isolated thunderstorms are occurring over the eastern Gulf. A 1011 mb low pressure system is located at the Bay of Campeche near 19N94W. Aided by divergent flow W of the upper low, Numerous moderate to strong convection is flaring up over the Bay of Campeche within 80 nm of 20N94W. Scattered moderate to isolated strong convection is evident farther N from 21N to 25N between 94W and the Mexican coast. Gentle to moderate E to SE winds and seas of 2 to 4 ft are found across the Gulf. Locally fresh winds and seas up to 5 ft are expected in areas of strong convection. For the forecast, a ridge will dominate the Gulf waters over the next several days producing mainly moderate E to SE winds. Fresh east to southeast winds are expected at night near the western Yucatan Peninsula through Fri due to local effects induced by a thermal trough. Another trough will persist over the SW Gulf over the next several days producing showers and thunderstorms. Winds and seas may be higher near thunderstorms. CARIBBEAN SEA... See Tropical Wave section above for details on convection near the Lesser Antilles. Strong to near gale E trades are present over the S central and SW Caribbean this morning. Seas are from 8-13 ft. Gentle to moderate trade winds and seas of 3 to 5 ft prevail across the eastern basin. While moderate to fresh trades and seas of 6 to 9 ft are seen across the northwestern basin. For the forecast, a tropical wave located just east of the Lesser Antilles is quickly moving west to west-northwestward. It will pass through the Lesser Antilles today, then across the eastern and central Caribbean Sea later this week. Locally heavy rain from disorganized showers and thunderstorms can be expected over portions of the Lesser Antilles during the next day or two. Farther east, a broad low pressure associated with a tropical wave midway between the west coast of Africa and the Windward Islands is producing a large area of showers and thunderstorms that continue to show some signs of organization. Conditions appear favorable for development and a tropical depression is likely to form during the next few days while the system moves WNW at 17 kt. The system will likely move through the Windward and Leeward islands on Fri. ATLANTIC OCEAN... See Tropical Wave section above for details on convection across the tropical Atlantic Basin. An upper-level trough reaches WSW from a low near Bermuda at 32N64W to near the Bahamas at 28N72W, then turns WNW to N Florida. Scattered showers are found north of 29N from 58W to 63W. Divergent flow south of these upper features is triggering scattered showers and thunderstorms from the Bahamas northwestward to Florida. Otherwise, a surface ridge extending WSW from a 1025 mb high near 28N48W dominates the mid Atlantic Basin. Gentle winds and seas of 3 to 5 ft are N of 23N, while moderate to fresh E winds and seas of 6 to 8 ft are present from 06N to 23N. Gentle to moderate E winds and seas of 4 to 6 ft are seen elsewhere. For the forecast W of 65W, the Atlantic ridge will build westward and dominate the forecast waters the remainder of the week. Fresh to strong winds are expected just north of Hispaniola Thu night through Sun night due to the pressure gradient between the Atlantic ridge and a couple of tropical wave passages over the Caribbean Sea. $$ Chan/Landsea