000 AXNT20 KNHC 192318 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Tue Jun 20 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Tropical Storm Bret has formed in the central Atlantic. Interest in the Lesser Antilles should monitor this system. At 19/2100 UTC, Bret is centered near 11.3N 42.2W or about 1125 nm E of the Southern Windward Islands moving W at 18 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Satellite imagery continues to show that the system is becoming better organized, with convective banding and a dense central overcast. On the forecast track, the system should be approaching the Lesser Antilles late this week. Bret is forecast to strengthen and move across the Lesser Antilles as a hurricane on Thursday and Friday, bringing a risk of flooding from heavy rainfall, hurricane-force winds, and dangerous storm surge and waves. Given the larger than usual uncertainty in the track forecast, it is too early to specify the location and magnitude of where these hazards could occur. However, everyone in the Lesser Antilles, Puerto Rico, and the Virgin Islands should closely monitor updates to the forecast for Bret and have their hurricane plan in place. Please read the latest HIGH SEAS FORECAST issued by National Hurricane Center at wed-site 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. A tropical wave (AL93) located several hundred miles south- southwest of the Cabo Verde Islands continues to produce a large area of disorganized showers and thunderstorms. Its axis is along 29W S of 15N moving W at 10 to 15 kt. A 1012 mb low pressure is analyzed along the wave axis near 08.5N29W. A cluster of moderate convection is within about 150 nm NW quadrant of low center. Another cluster of moderate to strong convection is to the W covering the area from 08N to 11N between 32W-34W. Environmental conditions appear favorable for further development of this system, and a tropical depression could form in a couple of days while the system moves westward across the eastern and central tropical Atlantic. The latest Tropical Weather Outlook gives this system a medium chance of tropical cyclone formation in the next 48 hours, as well as 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 is along 51W S of 16N moving W at 10-15 kt. A small area of moderate convection is near the northern end of the wave axis. A tropical wave is along 74W/75W S of 15N, extending inland across western Colombia and moving W at 10-15 kt. Currently, no significant convection is occurring near this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 16N16W to 1012 mb low pressure located near 08.5N29W to 10N36W. No ITCZ is currently present. Aside from the convection associated with the tropical waves and Tropical Storm Bret, no significant convection is noted. GULF OF MEXICO... The Atlantic ridge extends across Florida into the Gulf waters. The pressure gradient between the ridge and lower pressure inland Mexico supports moderate to fresh southerly winds across the western half of the Gulf, and a gentle to moderate anticyclonic flow across the eastern half of the Gulf. Seas are generally 3-5 ft W of 85W and 1-3 ft elsewhere. A short-wave trough is helping to induce showers and thunderstorms over South Florida. A diffluent pattern aloft is also enhancing convection along the coastal waters between Alabama and the Florida Big Bend. Smoke due to agriculture fires over Mexico may be reducing visibilities along the coast of Mexico and the western Bay of Campeche where the latest SAB analysis indicates a medium concentration. For the forecast, high pressure extending from the Straits of Florida to the upper Texas coast will generally persist through the week. 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 approach the Lesser Antilles late this week. The most recent satellite derived wind data provide observations of fresh to strong trade winds across the south-central Caribbean. Seas are 8-9 ft within these winds. Seas of 6-8 ft dominate the waters from 10N-17N between 70W-82W. Moderate to fresh winds are noted in the Gulf of Honduras with seas of 3-5 ft. Gentle to moderate winds prevail elsewhere except in the lee of Cuba where light to gentle winds are seen. Showers and thunderstorms have flared-up over northern Nicaragua and NE Honduras and regional waters. A surface trough is noted across this area along 84W. Similar convective activity is also noted over parts of the Greater Antilles. For the forecast, 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 winds are expected in the Gulf of Honduras. Recently upgraded Tropical Storm Bret will move to 11.7N 44.8W Tue morning, 12.2N 47.7W Tue afternoon, 12.7N 50.3W Wed morning, strengthen to a hurricane near 13.2N 52.9W Wed afternoon, 13.7N 55.5W Thu morning, and 14.3N 58.3W Thu afternoon. Bret will change little in intensity as it moves to 15.5N 63.6W Fri afternoon. ATLANTIC OCEAN... Please refer to the Special Features section for information on Tropical Storm Bret. A surface trough is an analyzed E of Florida and runs from 31N75W to South Florida near 25N81W. gentle to moderate winds are on either side of the trough. Showers and thunderstorms have developed over South Florida under a southwesterly flow ahead of a mid-upper level trough extending across the eastern CONUS. This convective activity is also affecting the NW Bahamas. The Bermuda-Azores high dominates the remainder of the Atlantic forecast waters with a 1027 mb high center near 32N48W. The pressure gradient between the high pressure and T.S. Bret is resulting in an area of fresh NE winds roughly from 14N-23N between 40W and 50W. Gentle to moderate anticyclonic flow is noted elsewhere with light to gentle winds near the high pressure center. Outside of Bret, and E of 70W, seas are generally 4-6 ft, and 2-4 ft W of 70W and E of the Bahamas. For the forecast W of 55W, the Bermuda high will continue to dominate the forecast are through mid-week. A weak cold front off the SE US coast will linger and gradually dissipate through the early part of the week with locally fresh winds E of it tonight. Mainly gentle to moderate anticyclonic winds will prevail the next several days, locally fresh offshore N Hispaniola and offshore N Florida. Recently upgraded Tropical Storm Bret will move to 11.7N 44.8W Tue morning, 12.2N 47.7W Tue afternoon, 12.7N 50.3W Wed morning, strengthen to a hurricane near 13.2N 52.9W Wed afternoon, 13.7N 55.5W Thu morning, and 14.3N 58.3W Thu afternoon. Bret will change little in intensity as it moves to 15.5N 63.6W Fri afternoon. $$ GR