000 AXNT20 KNHC 210357 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Wed Jun 21 2023 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 0000 UTC surface analysis and satellite imagery through 0350 UTC. ...SPECIAL FEATURES... Tropical Storm Bret: Tropical Storm Bret is centered near 12.5N 50.2W at 21/0300 UTC or about 630 nm E of the Windward Islands moving W or 280 degrees at 15 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Seas 8 ft or greater reach as far north as 17N. Seas 12 ft or greater are observed within 60 nm N semicircle and 30 nm SE quadrant of center with maximum sea heights to 16 ft. Bret has become a little better organized this evening, with increased convection near and north of the center and some outer bands developing in the eastern semicircle. On the forecast track, the center of Bret is expected to move across the Lesser Antilles Thursday afternoon as a tropical storm bringing a risk of flooding from heavy rainfall, strong winds, and dangerous waves along the coast. Given the uncertainty in the track and intensity forecasts, it is too early to specify the location and magnitude of where Bret's associated hazards could occur. A Tropical Storm Watch has been issued for Barbados, Dominica, Martinique, and St. Lucia Please read the latest HIGH SEAS FORECAST issued by National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest T.S. Bret Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Invest Area (AL93): A tropical wave extends along 35W from 03N to 15N, moving west at about 15 kt. A 1011 mb low is analyzed along the wave near 10N35W. Showers and thunderstorms have started to redevelop after an earlier lull in activity. Strong winds are noted in the northern semicircle of the low, where seas are in the 6-8 ft range. Environmental conditions appear conducive for further development of this system, and a tropical depression will likely form during the next couple of days while the system moves westward at 10 to 15 kts across the central Atlantic. The latest Tropical Weather Outlook assigns a high (70%) chance of tropical cyclone formation in the next 48 hours, and a high (80%) chance over the next seven days. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave extends along 60W from 05N to 17N, moving west at around 15 kt. Scattered convection is observed from 11N to 17N between 58W and 62W. A tropical wave extends along 81W from 04N to 15N, moving west at around 10 kt. Isolated moderate convection is observed from 11N to 15N between 80W and 82W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 12N17W, through Invest Area AL93 near 10N35W, to 10N43W. No ITCZ is currently present in the Atlantic. A large cluster of numerous moderate with scattered strong convection is observed along the W coast of Africa from 05N to 11N east of 18W. This activity may be signaling the next tropical wave will soon emerge off the coast of Africa. ...GULF OF MEXICO... A stationary front extends across the southern U.S. Gulf Coast to northern Florida. Numerous showers and thunderstorms are observed north of 26N between 84W and 94W. Similar convection is noted over much of the state of Florida and surrounding coastal waters. Otherwise, a high-pressure ridge continues to dominate the basin. Anticyclonic winds are mostly gentle to moderate outside of thunderstorms. Another exception is near the Yucatan Peninsula, where a surface trough is supporting fresh to strong winds. Seas are generally 3-5 ft across the basin, with buoys reporting up to 7 ft within thunderstorms in the NE Gulf. For the forecast, high pressure extending from the Straits of Florida to the upper Texas coast will generally persist through the week and into the upcoming weekend. Fresh winds will pulse north of the Yucatan peninsula each night through the forecast period as a diurnal trough develops and moves offshore. Elsewhere, gentle to moderate winds will prevail, locally fresh at times. Smoke from agricultural fires in Mexico will produce hazy skies over the central and western Gulf for at least the next day or two. ...CARIBBEAN SEA... Please refer to the Special Features section for information on Tropical Storm Bret, which is forecast to move across portions of the Lesser Antilles Thursday afternoon and Thursday night. The gradient between subtropical high pressure and lower pressure over northern Colombia is supporting fresh to strong trade winds in the central Caribbean, where seas are in the 7-10 ft range. Strong winds are also noted in the Gulf of Honduras. Winds are gentle to moderate elsewhere, with 3-6 ft seas. For the forecast, Tropical Storm Bret near 12.2N 48.6W 1006 mb at 5 PM EDT moving W at 16 kt. Maximum sustained winds 40 kt gusts 50 kt. Bret will begin to gradually strengthen as it moves to near 12.6N 50.8W late tonight, to near 13.1N 53.4W Wed afternoon with maximum sustained winds 50 kt gusts 60 kt, to near 13.5N 55.9W late Wed night, to near 13.9N 58.8W Thu afternoon with maximum sustained winds 55 kt gusts 65 kt, then move across the Lesser Antilles Thu night and into the far eastern Caribbean Sea near 14.2N 62.0W by late Thu night. Bret is forecast to weaken as it moves west-northwest across the eastern and central Caribbean Fri through Sat, eventually dissipating on Sun. Otherwise, the pressure gradient between the Bermuda High and the Colombian Low will support fresh to strong E trades across the central Caribbean through early Thu. Moderate to fresh E to SE winds are expected in the Gulf of Honduras through late Wed night, then increase to fresh to strong through Thu, to near gale Thu night and diminish back to fresh to strong Fri and Fri night. ...ATLANTIC OCEAN... Please refer to the Special Features section for information on Tropical Storm Bret and Invest Area AL93. Scattered showers and thunderstorms are observed in the far western subtropical Atlantic near Florida and the Bahamas. SW winds are moderate to fresh in this area. Otherwise a 1025 mb high pressure centered near 30N44W dominates the weather pattern. Winds are generally gentle to moderate north of 25N and moderate to fresh south of 25N. Seas are 3-6 ft outside of impacts from Tropical Storm Bret. For the forecast W of 55W, broad high-pressure ridging extending southwest across the area will continue to control the weather regime throughout during the rest of the forecast period. Moderate to fresh south to southwest winds N of 27N and W of 70W will change little through the end of the week. Otherwise, mainly gentle to moderate anticyclonic winds will prevail the next several days, locally fresh offshore N Hispaniola and offshore N Florida. $$ Flynn