000 AXNT20 KNHC 190005 TWDAT Tropical Weather Discussion...UPDATED NWS National Hurricane Center Miami FL 0005 UTC Wed Aug 18 2021 Updated to include the information from the Intermediate Advisory of Hurricane Grace 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Hurricane Grace is centered near 19.8N 84.9W at 19/0000 UTC or 148 nm E of Tulum Mexico moving WNW at 14 kt. Estimated minimum central pressure is 989 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Numerous moderate and scattered strong convection is noted from 16N-22N between 80W-85W. Peak seas are 25 ft. A general west-northwestward to westward motion is expected for the next several days. On the forecast track, Grace is expected to make landfall in the eastern Yucatan Peninsula Thursday morning, move over the Yucatan Peninsula on Thursday, and move over the southwest Gulf of Mexico Thursday night or early Friday. Seas may reach 30 ft in the NW Caribbean before landfall in Yucatan and then redevelop to 25 ft in the SW Gulf of Mexico. 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 is centered near 29.9N 67.6W at 18/2100 UTC or 200 nm SW of Bermuda moving W at 8 kt. Estimated minimum central pressure is 995 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Peak seas are near 20 ft. Numerous moderate and scattered strong convection is noted from 28N-32N between 65W-69W. A turn to the north is expected on Friday with that motion continuing into the weekend. Little change in strength is forecast during the next day or so, but Henri is expected to become a hurricane on Friday. Peak seas should continue near 20 ft through Friday morning, before diminishing in our waters as Henri moves northward. 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 WAVES... A new Atlantic tropical wave was identified near 23W from 19N southward. Scattered moderate convection is seen from 03N-13N between 22W-28W. A far eastern Atlantic tropical wave has its axis along 34W from 19N southward, moving westward at around 10 kt. Scattered moderate convection is seen from 07N-13N between 30W-38W. A central Atlantic wave has its axis along 51W south of 20N, moving westward at 15 kt. No significant deep convection is currently associated with this wave. A tropical wave over the eastern Caribbean has its axis along 66W from 20N southward, moving westward at 15 kt. No significant deep convection is currently associated with this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from Senegal near 12N18W to 09N50W. The ITCZ then extends from 08N51W to 09N61W. Aside from the convection associated with the tropical waves along 26W, no significant deep convection is occurring. ...GULF OF MEXICO... Fairly tranquil weather conditions prevail across most of the Gulf of Mexico. However, moderate to fresh NE to E winds are over the SE Gulf waters including the Yucatan Channel. Elsewhere, light and gentle winds prevail in the basin north of 24N with seas 3-5 ft in the SE Gulf and 1-3 ft elsewhere. No significant deep convection is currently occurring over the Gulf. For the forecast, Hurricane Grace near 19.7N 83.7W 992 mb at 5 PM EDT moving WNW at 14 kt. Maximum sustained winds 70 kt gusts 85 kt. Grace will move to 20.2N 86.1W Thu morning, move inland and weaken to a tropical storm near 20.7N 89.3W Thu afternoon, 20.9N 92.2W Fri morning, strengthen to a hurricane near 20.8N 94.6W Fri afternoon, inland to 20.4N 97.3W Sat morning, and move inland and weaken to a tropical depression near 20.0N 99.9W Sat afternoon. Winds and seas will begin to increase across the southeastern Gulf ahead of Grace tonight. These conditions will shift to west of 90W Thu through late Fri night. ...CARIBBEAN SEA... Refer to the Special Features section above for details on Hurricane Grace. Outside of the wind field of Tropical Storm Grace, strong to near gale-force NE to E trades in the south-central Caribbean Sea, especially within 90 nm of the NW coast of Colombia. Fresh to strong trades are noted in the rest of the central and E Caribbean. Gentle to moderate trades are found in the rest of the basin. Latest observations indicate seas are 5-7 ft in the central and E Caribbean, and 1-3 ft SW Caribbean. For the forecast, Hurricane Grace near 19.7N 83.7W 992 mb at 5 PM EDT moving WNW at 14 kt. Maximum sustained winds 70 kt gusts 85 kt. Grace will move to 20.2N 86.1W Thu morning, move inland and weaken to a tropical storm near 20.7N 89.3W Thu afternoon, 20.9N 92.2W Fri morning, strengthen to a hurricane near 20.8N 94.6W Fri afternoon, inland to 20.4N 97.3W Sat morning, and move inland and weaken to a tropical depression near 20.0N 99.9W Sat afternoon. Elsewhere, fresh to strong trades will be over the central Caribbean through early Thu. ...ATLANTIC OCEAN... Please refer to the sections above for details on Tropical Storm Henri and on the tropical waves moving across the basin. An expansive 1026 mb Azores ridge dominates the tropical Atlantic, resulting in fairly tranquil weather conditions. The strong high pressure system and lower pressures over NW Africa result in a tight pressure gradient over the NE Atlantic. Fresh to strong NE winds are occurring surrounding the Canary Islands and off the coasts of Morocco and Western Sahara. Seas in this area are in the 5-7 ft range. Elsewhere the NE to E trades are moderate to fresh. Seas are generally 5-7 ft. For the forecast west of 65W, Tropical Storm Henri near 29.9N 67.6W 995 mb at 5 PM EDT moving W at 8 kt. Maximum sustained winds 60 kt gusts 75 kt. Henri will move to 29.8N 69.0W Thu morning, 29.8N 70.7W Thu afternoon, strengthen to a hurricane near 30.1N 72.3W Fri morning, 31.0N 73.2W Fri afternoon, 32.7N 72.7W Sat morning, and 35.2N 71.7W Sat afternoon. Elsewhere, high pressure will persist across the forecast waters through the period. Fresh east to southeast winds over the far southwest part of the area will shift W to the Straits of Florida tonight. $$ NATIONAL HURRICANE CENTER