000 AXNT20 KNHC 171752 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Tue Aug 17 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 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... Tropical Storm Grace near 18.3N 76.8W 1005 mb at 11 AM EDT moving W at 13 kt. Maximum sustained winds 45 kt gusts 55 kt. Estimated Minimum central pressure is 1005 mb. Satellite imagery shows numerous moderate to strong impacting Jamaica, the Windward Passage and adjacent coastal waters this afternoon. Peak seas are currently at 9 ft near the center of Grace, and are expected to build to near at 18 ft by Thursday. A general westward to west-northwestward motion is expected for the next several days. On the forecast track, the center of Grace will continue to move near the northern coast of Jamaica this afternoon. Grace is forecast to move near or over the Cayman Islands late tonight and early Wednesday, and then approach the Yucatan peninsula late Wednesday or early Thursday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT2.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more details. Tropical Storm Henri near 30.4N 64.3W 1004 mb at 11 AM EDT moving WSW at 5 kt. Maximum sustained winds 45 kt gusts 55 kt. Satellite imagery shows increasing numerous moderate convection within 160 nm NE and SE quadrant. Seas are currently 8-10 ft near Henri, and are expected to build to 16 ft by tonight. A faster motion toward the west is forecast by tonight, followed by a motion to the west-northwest or northwest by late Thursday. On the forecast track, the center of Henri should pass well to the south of Bermuda through tonight. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for more details. Tropical Depression Fred is centered inland near 33.4N 84.7W. The depression is moving toward the north-northeast near 14 kt and this motion is expected to continue through today with a gradual acceleration to the northeast through Wednesday. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. Convection is no longer impacting the Gulf of Mexico. Future information on this system can be found in Public Advisories issued by the Weather Prediction Center, under AWIPS header TCPAT1, WMO header WTNT31 KWNH, and on the web at http://www.wpc.ncep.noaa.gov. ...TROPICAL WAVES... A far eastern Atlantic tropical wave was introduced along 21N from 06N to 21N, moving westward at 10-15 kt. Increasing numerous moderate convection is from 05N-16N between and east of 24W to the coast of Africa. An eastern Atlantic tropical wave has its axis along 21W from 02N to 22N. It is moving westward near 15 kt. Scattered showers and thunderstorms are from 02N-09N between 34W-42W. A central Atlantic tropical wave has its axis along 56W from 20N southward to inland Suriname. It is moving westward at 10-15 kt. Scattered showers and thunderstorms are noted from 07N to 10N Between 53W to 60W to inland the coast Venezuela. A western Caribbean tropical wave has its axis along 86W from 21N southward to northern Costa Rica, moving westward at 10-15 kt. Scattered showers and thunderstorms are noted on the southern end Of the wave axis over the eastern Pacific from 05N to 11N between 82W to 89W. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from Senegal near 13N16W to 08N44W, then transitions to ITCZ from 08N44W to 08N53W. Aside from the convection associated with the tropical waves, scattered moderate convection is seen south of the monsoon trough from 02N to 10N between 41W-36W. ...GULF OF MEXICO... With Tropical Depression Fred continuing to move farther inland, the gradient is relaxed over the Gulf of Mexico. Light and gentle winds are observed across the Gulf with seas 2 to 3 ft. Tropical Storm Grace near 18.3N 76.8W 1005 mb at 11 AM EDT moving W at 13 kt. Maximum sustained winds 45 kt gusts 55 kt. Grace will move to 18.8N 79.0W this evening, strengthen to a hurricane near 19.2N 82.2W Wed morning, 19.7N 85.3W Wed evening, inland to 20.4N 88.3W Thu morning, weaken to a tropical storm near 20.9N 91.3W Thu evening, and strengthen to a hurricane near 21.1N 94.0W Fri morning. Grace will move inland near 21.5N 98.5W early Sat. Grace is forecast to approach the Yucatan Peninsula late Wednesday or early Thursday. Fresh to strong easterly winds on the northern periphery of Grace are expected over the southeastern Gulf waters from Tue night through Wed night. ...CARIBBEAN SEA... Refer to the Special Features section above for details on Tropical Storm Grace. Outside of the wind field of Grace, overnight ASCAT data passes showed moderate to fresh winds in the eastern and central Caribbean and light to gentle trades in the western Caribbean, pulsing to moderate in the Gulf of Honduras. Seas are 5-7 ft in the east-central Caribbean, 4-6 ft near the Windward Islands, 3-5 ft near the Leeward Islands and in the west-central Caribbean, and 3 ft or less in the western Caribbean. For the forecast, Tropical Storm Grace near 18.3N 76.8W 1005 mb at 11 AM EDT moving W at 13 kt. Maximum sustained winds 45 kt gusts 55kt. Grace will move to 18.8N 79.0W this evening, strengthen to a hurricane near 19.2N 82.2W Wed morning, 19.7N 85.3W Wed evening, inland to 20.4N 88.3W Thu morning, weaken to a tropical storm near 20.9N 91.3W Thu evening, and strengthen to a hurricane near 21.1N94.0W Fri morning. Grace will move inland over near 21.5N 98.5W early Sat. Grace is forecast to move near the Cayman Islands tonight, and then approach the Yucatan peninsula late Wednesday or early Thursday. Elsewhere, fresh to strong northeast to east trades will be over the central Caribbean Tue through Wed night. ...ATLANTIC OCEAN... Please refer to the Special Features section above for details on Tropical Storm Henri. The tight pressure gradient in the eastern Atlantic near the Canary Islands continues to support near gale force NE winds, which were detected by the latest scatterometer pass this morning. Seas 6-9 ft are noted in the areas of strongest wind. Elsewhere, surface ridging and a weak pressure gradient prevails. Fresh trades are noted from the Turks and Caicos south to the coast of Hispaniola, and in the Windward Passage with seas of 3-6 ft. Gentle to moderate E to SE winds are over the western Atlantic, including the Bahamas and areas north of the Turks and Caicos. Light winds are north of 22N between 40W and 67W excluding the area near the Tropical Storm Henri. Gentle to moderate trades are south of 24N in the remainder of the basin, except moderate to fresh NE winds north of 25N east of 20W. Seas are generally 3-6 ft across the basin, with the highest seas near Hispaniola and southeastern Bahamas. For the forecast west of 65W, Tropical Storm Henri near 30.4N 64.3W 1004 mb at 11 AM EDT moving WSW at 5 kt. Maximum sustained winds 45kt gusts 55kt. Henri will move to 30.4N 65.1W this evening, 30.3N 66.5W Wed morning, 30.3N 68.2W Wed evening, 30.4N 69.7W Thu morning, 30.7N 70.6W Thu evening, and 31.6N 71.3W Fri morning. Henri will change little in intensity as it moves to near 34.1N 69.6W early Sat. On the forecast track, the center of Henri should pass well to the south of Bermuda through tonight. Otherwise, high pressure will persist across the forecast waters through the period. $$ MMT