000 AXNT20 KNHC 181751 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Wed Oct 18 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 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... Central Tropical Atlantic (AL94) Storm Warning: A 1008 mb low pressure system is located about 600 nm east of the Windward Islands, near 12.4N48.6W. Numerous moderate to scattered strong convection is evident on satellite imagery from 05N to 14N and between 43.5W and 52W. Satellite-derived wind data indicated that the system is already producing winds to tropical storm force. Seas of 8-14 ft are found from 10N to 21N and between 44.5W and 54W. Continued development is anticipated, and a tropical storm is expected to form later today or tonight while moving westward or west-northwestward toward the Lesser Antilles. Regardless of development, this system has the potential to bring gusty winds, heavy rainfall, and flash flooding to portions of the Lesser Antilles beginning on Friday. The chance of tropical cyclone formation within the next 48 hours is high. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. A gale warning is already in effect in association with AL94. Additional information regarding the Gale and Storm Warnings can be found in the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the Atlantic through the coast of Guinea-Bissau near 11.5N16W and continues southwestward to 04N27W to 03N38W. The ITCZ extends from 03N38W to 01N50W. Scattered moderate to isolated strong convection is observed within 150 nm N and within 390 nm S of both axes. ...GULF OF MEXICO... A 1019 mb high pressure is centered along the southeast coast of Louisiana. This high pressure is dominating the sensible weather in the Gulf of Mexico. As dry continental airmass enveloping the basin is suppressing the development of deep convection. However, a weak surface trough in the Bay of Campeche allows for shallow showers in the area. Light to gentle anticyclonic winds prevail over the northern Gulf with 1 to 3 ft seas. Moderate NE winds are over the southern Gulf with seas of 3 to 6 ft. For the forecast, the aforementioned high pressure will continue to dominate the Gulf waters through Thu night. Gentle to moderate anticyclonic winds will prevail through Thu night. A frontal system will bring fresh winds to the NE Gulf Fri and Fri night. Benign conditions will then return over the weekend as high pressure builds back in. ...CARIBBEAN SEA... A stationary front extends from eastern Cuba to NE Honduras. Scattered moderate to strong convection is along the front to the east of 86.5W. Similar activity is noted within 150 nm of the coast of Nicaragua, Costa Rica, and Panama. Fresh to strong NE winds and seas of 5 to 8 ft are occurring over the western Caribbean. Gentle to moderate winds prevail over most of the basin, east of the stationary front, except for fresh trades in the south- central Caribbean. Seas are 4 to 5 ft in the south- central Caribbean, and 2 to 4 ft elsewhere east of the stationary front. For the forecast, the aforementioned stationary front should remain in place through today before dissipating tonight. Fresh to locally strong NE winds and seas of 6 to 8 ft will persist over the northwest Caribbean through today as high pressure builds over the area. Looking ahead, a broad area of low pressure located about 850 miles east of the Windward Islands continue to show signs of organization. It has a high chance of tropical cyclone formation through 48 hours. Interests in the Lesser Antilles should monitor the progress of this system, and watches may be required for some of the islands later today. ...ATLANTIC OCEAN... Please see the Special Features section above for more details on Invest 94L located well east of the Lesser Antilles. A stationary front remains draped across the western Atlantic from 31N62W to eastern Cuba. Scattered moderate to isolated strong convection is noted along the front. The strongest convection is depicted from 26N to 31N between 66W and 71.5W. It is in this area where recent scatterometer data revealed that winds are out of the north and near-gale. A surface trough extends from 31N68W to 29N74W. Another surface trough extends northeastward from the Virgin Islands to 25N62W. Scattered moderate thunderstorms are within 70 nm of the trough axis. Outside of convection, west of 65W, winds are gentle to moderate and seas are 3 to 6 ft. An upper-level low east of the Lesser Antilles is producing scattered to isolated strong convection from 17N to 22N between 52W and 58W. Recent scatterometer data revealed that winds are strong to near-gale in association with the convection. Farther east, broad ridging is leading to gentle winds from 25N to 31N between 29W and 60W, anchored by a 1022 mb high pressure centered near 27.5N46W. Seas are 5 to 7 ft across the area. To the south of 25N and east of 62W, moderate to fresh winds and seas of 6 to 8 ft cover much of the area, but these winds and seas increase closer to AL94. For the forecast W of 55W, the aforementioned stationary front will remain in place before dissipating Thu. High pressure will build over the area in the wake of the front. The next frontal system will move offshore the southeastern United States Fri night. Fresh to strong winds and rough seas are forecast north of 27N Fri night through Sat night with this system. Looking ahead, a broad area of low pressure located about 850 miles east of the Windward Islands continue to show signs of organization. It has a high chance of tropical cyclone formation through 48 hours. Interests in the Lesser Antilles should monitor the progress of this system, and watches may be required for some of the islands later today. $$ KRV