000 AXNT20 KNHC 141056 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sat Aug 14 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 0600 UTC surface analysis and satellite imagery through 1045 UTC. ...SPECIAL FEATURES... Tropical Depression Fred is just inland the coast of north-central Cuba near 23.3N 81.7W at 0900 UTC, or about 78 nm S of Key West, Florida. It is moving WNW at 9 kt with an estimated minimum central pressure at 1013 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Wave heights with Fred are in the 8-10 ft range. Latest satellite imagery shows scattered moderate to isolated strong convection just south of Cuba from 20N to 22N and between 78W-82W. Scattered moderate convection is over the Straits of Florida between the Florida Keys and central Cuba. Fred is expected to continue moving WNW near the N coast of central Cuba through this morning, then turn to the NW tonight, followed by a a northward motion by Sunday night. On the forecast track, Fred is expected to pass west of the lower Florida Keys this afternoon, move across the eastern Gulf of Mexico tonight through Mon, and move inland over the northern Gulf coast Mon night. Rainfall amounts of 3 to 5 inches with locally amounts up to 8 inches are possible over the Keys and southern Florida. Across the Florida Big Bend and Panhandle, 3 to 7 inches with isolated maximum totals of 10 inches are expected. 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 NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Recently upgraded Tropical Storm Grace is located near 15.8N 55.6W at 0900 UTC or about 365 nm east of the Leeward Islands. It is moving W at 19 kt, with an estimated minimum central pressure of 1007 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Wave heights with this system are in the 8-10 ft range. Satellite imagery shows that Grace is a small tropical storm. Just over the past few hours large bursts of numerous moderate to strong convection have become evident within 210 nm of the center in the W quadrant. Grace is forecast to decrease its forward motion during the next few days. On the forecast track, the center of the storm is forecast to move over the Leeward Islands tonight, over the Virgin Islands and Puerto Rico on Sun, and then over the Dominican Republic on Mon. Some strengthening is forecast during the next couple of days. Weakening is expected early next week as the system interacts with the Greater Antilles. 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 NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A new tropical wave is analyzed just off the coast of Africa along 18N from 04N to 20N. It is moving westward at about 15 kt. Scattered moderate convection is east of the wave to the coast of Africa from 06N to 14N. A far eastern Atlantic tropical wave has its axis along 31W from 04N to 21N, moving westward near 20 kt. No significant convection is associated to this wave. The central Atlantic tropical wave that earlier was along 53W is no longer identifiable. An eastern Caribbean Sea tropical wave has its axis along 66W south of 24N to inland South America. It is moving westward at about 10 kt. Enhanced by an upper-level low to the north near 29N61W, scattered to numerous moderate convection is noted from 20N to 25N between 58W-66W. Scattered moderate to isolated strong convection is north of Venezuela, and across central Venezuela. This wave has a good track history. A western Caribbean Sea tropical wave is along 84W from 19N southward along the east coast of Honduras and Nicaragua to Costa Rica, and is moving westward at 10-15 kt. No deep convection is associated with this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough extends across the coast of Mauritania near 18N16W to 08N25W and to 06N35W. The ITCZ then continues from 06N35W to near 07N43W to 05N51W. Scattered moderate to isolated strong convection is within 180 nm south of the monsoon trough between 20W-28W. Scattered moderate convection is within 60 nm north of the ITCZ between 41W-46W. ...GULF OF MEXICO... An elongated upper-level low across the eastern Gulf near 26N84W is triggering scattered showers and isolated thunderstorms over the SE Gulf and W coast of Florida. Otherwise a modest ridge of high pressure across the northern Gulf coast states is supporting gentle winds and low seas of 1 to 3 ft over most of the Gulf. The exception will be the southeastern Gulf and Straits of Florida, increasing pressure gradient between the ridge and Tropical Depression Fred is creating moderate to locally fresh winds and seas in the range of 4 to 6 ft. For the forecast, expect deteriorating marine conditions across most of the water east of 90W through the weekend and into early Mon due to Fred. Tropical Depression Fred was near 23.3N 81.7W 1013 mb at 5 AM EDT moving WNW at 11 kt. Maximum sustained winds 30 kt gusts 40 kt. Fred will move to near 24.0N 83.1W this afternoon, then strengthen to a tropical storm near 25.4N 84.6W late tonight with maximum sustained winds 35 kt gusts 45 kt and slowly strengthen as it moves to near 27.0N 85.8W Sun afternoon, to near 28.4N 86.7W late Sun night with maximum sustained winds 45 kt gusts 55 kt, to near 29.8N 87.3W Mon afternoon with maximum sustained winds 50 kt gusts to 60 kt and inland to near 30.9N 87.4W late Mon night. Fred will weaken to a tropical depression while moving inland late Tue night. High pressure will then build over the area for the rest of the week. ...CARIBBEAN SEA... Refer to the Special Features section for information on Tropical Depression Fred, recently upgraded Tropical Storm Grace and the Tropical Waves section for convection in the Caribbean Basin. Gentle to moderate trade winds and seas at 4 to 6 ft are evident over the central and eastern basin. Light to gentle trades and seas of 1 to 3 ft are elsewhere over the basin. For the forecast, recently upgraded Tropical Storm Grace near 15.8N 55.6W 1007 mb at 5 AM EDT is moving W at 19 kt. Maximum sustained winds 35 kt gusts 45 kt. Grace will move to near 16.2N 58.5W this afternoon, to near 16.9N 61.8W late tonight, to near 17.7N 64.8W Sun afternoon with maximum sustained winds 45 kt gusts 55 kt, to near 18.3N 67.3W late Sun night, over the eastern Dominican Republic near 18.9N 69.4W Mon afternoon and remain over land near 19.8N 71.5W late Mon night with maximum sustained winds 40 kt gusts 50 kt. Grace will change little in intensity as it moves to near 21.9N 75.6W late Tue night and to near 24.5N 79.7W late Wed night. ...ATLANTIC OCEAN... Aided by divergent winds associated with an upper-level low over the eastern Gulf, a surface trough that is east of Florida along a position from 30N79W to West Palm Beach. Florida is producing scattered showers and isolated thunderstorms near the E Florida coast and NW Bahamas. For additional convection across the Atlantic Basin, refer to the Tropical Waves and Monsoon Trough/ITCZ sections above. For more information on Tropical Depression Fred and Tropical Storm Grace please read the Special Features section. The Atlantic ridge extends west-southwestward from the 1026 mb Azores high across Bermuda to northern Florida. Light to gentle winds and seas at 2 to 4 ft related to this ridge are found N of 25N between 27W and 72W. Moderate to locally fresh trades and seas of 4 to 6 ft are found from 10N to 25N between the African coast and Lesser Antilles, and between 72W and the Florida-Georgia coast. South of 10N, gentle to moderate winds and seas at 4 to 6 ft are present. For the forecast west of 65W, Tropical Depression Fred just inland north-central Cuba is forecast to move into the eastern Gulf of Mexico tonight as a possible tropical storm. Numerous showers and scattered thunderstorms over the far southwest part will gradually shift westward through tonight. Recently upgraded Tropical Storm Grace near 15.8N 55.6W 1007 mb at 5 AM EDT is moving W at 19 kt. Maximum sustained winds 35 kt gusts 45 kt. Grace will move to near 16.2N 58.5W this afternoon, to near 16.9N 61.8W late tonight, to near 17.7N 64.8W Sun afternoon with maximum sustained winds 45 kt gusts 55 kt, to near 18.3N 67.3W late Sun night, over the eastern Dominican Republic near 18.9N 69.4W Mon afternoon and remain over land near 19.8N 71.5W late Mon night with maximum sustained winds 40 kt gusts 50 kt. Grace will change little in intensity as it moves to near 21.9N 75.6W late Tue night and to near 24.5N 79.7W late Wed night. $$ Aguirre