000 AXNT20 KNHC 151107 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sun Aug 15 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 1100 UTC. ...SPECIAL FEATURES... The remnants of Fred are over the southeastern Gulf of Mexico near 24.4N 84.6W at 0900 UTC, or about 100 nm west of Dry Tortugas. It is moving NNW at 7 kt with an estimated minimum central pressure at 1012 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt presently within 100 nm NE of the its center. Wave heights with the remnants of Fred are in the 8-10 ft range. Latest satellite imagery shows scattered showers and thunderstorms from W Cuba northward to the Florida Keys. Fred will continue on its current motion through tonight, then turn toward the north expected on Mon. On the forecast track, the system will cross the southeastern Gulf of Mexico today, cross the east-central and northern Gulf of Mexico tonight and Monday, and move inland along the northern Gulf coast Mon night or early on Tue morning. Fred is expected to redevelop into a tropical storm later today, with gradual strengthening expected while it moves over the Gulf of Mexico until it makes landfall. 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 Storm Grace is over the eastern Caribbean Sea near 16.9N 64.4W at 0900 UTC or about 50 nm SSE of St. Croix. It is moving WNW at 14 kt, with an estimated minimum central pressure of 1010 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Wave heights with this system are in the 9-13 ft range. Satellite imagery shows that Grace is not a well organized tropical cyclone. Scattered moderate to strong convection is noted from 16N to 20N between 62W-67W and from 12N to 16N between 63W- 66W. Grace is forecast to move toward the west-northwest with a gradual decrease in forward speed during the next several days. Some strengthening is expected before Grace reaches Hispaniola on Monday. Weakening is forecast as the system crosses Hispaniola Mon and Mon night. Little change in strength is expected on Tue. 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... An Atlantic tropical wave has its axis along 25W from 04N to 19N, moving westward t 10 to 15 kt. Scattered moderate to isolated strong convection is within 180 nm east of the wave from 06N to 09N and within 120 nm west of the wave from A central Caribbean tropical wave has its axis along 73W from 25N southward across Haiti into NW Venezuela. It is moving westward at 15 to 20 kt Overnight ASCAT data showed a broad surface trough, especially on the northern portion of the wave. Aided by an upper-level trough southwest of Bermuda near 28N67W, scattered showers and isolated thunderstorms are present from 22N to 26N between 67W and 73W. A tropical wave has moved inland Central Americas near 89W south of 19N to across the southern Yucatan Peninsula and Guatemala and to the eastern Pacific. It is moving westward near 15 kt. Numerous moderate to strong convection that earlier developed along the southern coast of Guatemala and El Salvador has moved into the eastern Pacific Ocean. ...MONSOON TROUGH/ITCZ... A monsoon trough exits along the coast of Mauritania near 20N16W through a low pressure centered near 12N22W to 06N40W. The ITCZ then continues from 06N40W to 05N56W over N French Guiana. Numerous moderate to isolated strong convection is noted near and S of the monsoon trough from 10N to 17N between the African coast and 20W. Scattered moderate convection is near the monsoon trough from 01N to 07N between 27W and 36W. Scattered moderate to isolated strong convection is within 180 north of the ITCZ between 48W and 56W. ...GULF OF MEXICO... Refer to the Special Features section for information on the remnants of Fred. An upper level low over the NE Gulf near 29N85W is triggering scattered showers and isolated thunderstorms over the NE Gulf including the Big Band area and central W coast of Florida. Moderate to locally fresh S to SE winds and seas of 3 to 6 ft are expected near these thunderstorms. Gentle to moderate NE to E winds and seas at 2 to 4 ft prevail for the rest of the Gulf. For the forecast, the remnants of Fred near r24.4N 84.6W 1011 mb at 5 AM EDT moving NNW at 7 kt. Maximum sustained winds 35 kt gusts 45 kt. Fred will move to near 25.5N 85.6W this afternoon, to near 27.0N 86.6W Mon morning, to 28.5N 87.1W Mon afternoon, to 30.3N 87.1W Tue morning, inland to 32.5N 86.8W Tue afternoon, and inland to 35.0N 85.8W Wed morning. Fred will dissipate early Thu. Tropical Storm Grace over the eastern Caribbean Sea is forecast to move near the northern coast of Cuba and Straits of Florida Wed and Wed night and into the southeastern Gulf of Mexico Thu and Thu night. ...CARIBBEAN SEA... Refer to the Special Features section for information on Tropical Storm Grace and the Tropical Waves section for convection in the Caribbean Basin. Convergent trade winds are producing scattered showers and a few thunderstorms north f Colombia and Panama. Moderate with locally fresh trades and seas of 4 to 6 ft are present S central and SE Caribbean, while gentle to moderate trades and seas of 3 to 4 ft prevail across the rest of the basin. For the forecast, Tropical Storm Grace near 16.9N 64.4W 1010 mb at 5 AM EDT moving WNW at 18 kt. Maximum sustained winds 35 kt gusts 45 kt. Grace will move to near 17.5N 66.6W this afternoon, inland the eastern Dominican Republic near 18.3N 68.9W late tonight with maximum sustained winds 45 gusts 55 kt, continue inland near 18.9N 70.6W Mon afternoon with maximum sustained winds 35 gusts 45 kt, inland near 19.8N 72.6W late Mon night, to near 20.9N 75.3W Tue afternoon, and to near 22.0N 78.0W late Tue night. Grace will change little in intensity as it moves into the eastern Gulf of Mexico near 23.9N 82.5W late Wed night. ...ATLANTIC OCEAN... Refer to the Special Features section for information on Tropical Storm Grace. An upper-level low near 30N54W is producing scattered showers and thunderstorms north of 28N between 54W and 64W. Divergent flow east and southeast f an upper-level low of the NE Gulf is coupling with convergent SE winds to trigger scattered showers and isolated thunderstorms over SE Florida and off the Florida- Georgia coast. For additional convection across the Atlantic Basin, please read the Tropical Waves and Monsoon Trough/ITCZ sections above. The persistent Atlantic ridge over the N Atlantic continues to support light to gentle winds and seas at 2 to 4 ft N of 24N between 31W and 73W. Moderate with locally fresh NE to SE winds and seas of 5 to 7 ft are found N of 19N between the NW African coast and 31W, and also north of 20N between 73W and the Florida- Georgia coast. Gentle to moderate trades and seas of 4 to 6 ft are evident from 10N to 20N between the African coast and the Lesser Antilles. Mainly gentle southeast to southwest winds and seas of 4 to 5 ft prevail across the remainder of the basin. For the forecast west of 65W, Tropical Storm Grace near 16.9N 64.4W 1010 mb at 5 AM EDT moving WNW at 18 kt. Maximum sustained winds 35 kt gusts 45 kt. Grace will move to near 17.5N 66.6W this afternoon, inland the eastern Dominican Republic near 18.3N 68.9W late tonight with maximum sustained winds 45 gusts 55 kt, continue inland near 18.9N 70.6W Mon afternoon with maximum sustained winds 35 gusts 45 kt, inland near 19.8N 72.6W late Mon night, to near 20.9N 75.3W Tue afternoon, and to near 22.0N 78.0W late Tue night. Grace will change little in intensity as it moves into the eastern Gulf of Mexico near 23.9N 82.5W late Wed night. Otherwise, high pressure will persist across the area through the period. $$ Aguirre