000 AXNT20 KNHC 271803 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Wed Sep 27 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... Tropical Storm Philippe is centered near 17.5N 53.7W at 27/1500 UTC or 540 nm E of the Northern Leeward Islands, moving W at 8 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Peak seas are around 19 ft near and just northwest of the center. The radius of 12 ft or greater seas extends outward to 330 nm from the center in the NW semicircle. Scattered to numerous moderate with scattered strong convection is occurring within 300 nm of the center in the E semicircle. A westward to west- northwestward motion is expected over the next few days, with little change in strength over the next day or two. A slow weakening is forecast this weekend. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center, at the website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Gale Warning Associated with Invest Area (AL91): A central Atlantic tropical wave is near 43.5W from 17N southward through a 1007 mb low (AL91) at 11.6N43.5W, and moving west at around 15 kt. Scattered moderate to isolated strong convection is seen within 300 nm of the center in the northwest semicircle. A large area of fresh to near-gale force E to SE winds with 8 to 12 ft seas are present from 09N to 20N between 37W and 46W. Environmental conditions are forecast to be conducive for development, and a tropical depression or storm is expected to form in the next day or so while the system moves west- northwestward across the central tropical Atlantic. The chance of development within the next 48 hours is high. Gale force winds are forecast to develop with this low pressure near 13N44.5W this evening. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Tropical Weather Outlook at hurricanes.gov for more information. ...TROPICAL WAVES... Please refer to the SPECIAL FEATURES above for information on the tropical wave associated with AL91. A western Caribbean tropical wave is near 86W from 19N southward across Central America and into the East Pacific. It is moving west at around 10 kt. Aided by mid-level diffluent flow, scattered showers and thunderstorms are occurring from 15.5N to 21N between 81.5W and 87W. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic along the Mauritania coast near 18N16W to 07N23W to 07N31W. Scattered moderate convection is noted from 08N to 12N between 23W and 32W. ...GULF OF MEXICO... A broad surface trough extends from the north-central Gulf to the western Bay of Campeche. Isolated convection is depicted in the central Gulf in association with this trough. Scattered moderate convection is depicted in the north-central Gulf ahead of a frontal boundary. Another surface trough runs southwestward from northeastern Florida to Sarasota, Florida to 25N81.5W. Scattered moderate convection is noted from the Yucatan Channel northeastward to the Ft. Myers, FL area. Moderate SE winds and seas of 2-4 ft are noted in the southeastern Gulf, including the Yucatan Channel. Gentle winds and 1-3 ft seas prevail for the rest of the Gulf. For the forecast, a surface trough over the central Gulf will drift slowly W through tonight before dissipating. Scattered showers and isolated thunderstorms are expected to the east of the trough, over the eastern half of the Gulf, through tonight. Meanwhile, gentle to moderate NE to E winds and slight seas will prevail across the basin through early Thu. Winds are forecast to increase over the northern Gulf the end of the week into the weekend as high pressure ridging strengthens over the southeastern United States. ...CARIBBEAN SEA... An upper-level low over the eastern Caribbean Sea is producing scattered to numerous thunderstorms from 12N to 17N between 59W and 66W, including over the Lesser Antilles. Moderate to locally fresh trades and 4-6 ft seas prevail over the central Caribbean. Gentle to moderate trades and 3-5 ft seas prevail elsewhere. For the forecast, Tropical Storm Philippe is near 17.5N 53.7W at 11 AM EDT, and is moving west at 8 kt. Maximum sustained winds are 45 kt with gusts to 55 kt, and the minimum central pressure is 998 mb. Philippe will move to 18.0N 54.7W this evening, 18.6N 56.1W Thu morning, 19.0N 57.8W Thu evening, 19.0N 59.5W Fri morning, 18.9N 60.8W Fri evening, and 18.7N 62.2W Sat morning. Philippe will weaken to a remnant low near 18.4N 64.7W early Sun. Rough seas across the forecast zones east of the Leeward Islands generated by Tropical Storm Philippe will start to subside toward the end of the week. High pressure north of the area will support moderate to fresh trade winds across most of the eastern and central Caribbean through tonight. Winds across the Caribbean Sea will then diminish late this week into this weekend. ...ATLANTIC OCEAN... Refer to the SPECIAL FEATURES section above for details on Tropical Storm Philippe and a Gale Warning related to Invest AL91. Convergent southeasterly winds to the east of a surface trough over Florida are triggering scattered showers and isolated thunderstorms from the south of the western Bahamas northward to beyond 31N, mainly west of 73.5W. The Atlantic ridge associated with the Bermuda and Azores Highs is supporting light to gentle winds north of 26N between 28W and the Florida coast. Seas are 3- 5 ft west of 65W and north of 25N. South of 25N and west of 65W, moderate trades and 4-6 ft seas prevail. From 26N to 31N and between 30W and 65W, seas are 5-7 ft in mixed swell. Fresh to locally strong NE trades and 6-10 ft seas prevail in between the Canary Islands and Cabo Verde Islands. Strong winds and rough seas associated with Tropical Storm Philippe and Invest AL91 are occurring from 10N to 24N between 38W and 58W. For the forecast west of 55W, Tropical Storm Philippe is near 17.5N 53.7W at 11 AM EDT, and is moving west at 8 kt. Maximum sustained winds are 45 kt with gusts to 55 kt, and the minimum central pressure is 998 mb. Philippe will move to 18.0N 54.7W this evening, 18.6N 56.1W Thu morning, 19.0N 57.8W Thu evening, 19.0N 59.5W Fri morning, 18.9N 60.8W Fri evening, and 18.7N 62.2W Sat morning. Philippe will weaken to a remnant low near 18.4N 64.7W early Sun. Rough seas ahead of the storm are east of 60W, and will continue to spread east of 65W through the end of the week. Elsewhere, seas will build tonight and Thu north of the Bahamas and east of Florida in NE swell. $$ KRV