000 AXNT20 KNHC 192331 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Fri Aug 20 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Tropical Storm Grace is centered near 20.6N 90.2W at 19/2100 UTC or 40 nm NNE of Campeche Mexico moving W at 13 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Peak seas are currently 15 ft just N of the Yucatan peninsula. An area of 12-14 ft seas is noted between Cozumel and Cancun. Scattered moderate isolated strong convection is from 19N to 21N between 86W and 91W, including portions of the NW Caribbean and the E Bay of Campeche. Convection associated with an outer band of Grace is also affecting parts of Belize. Gusty winds and heavy rain will continue over the Yucatan peninsula through tonight. On the forecast track, Grace is expected to emerge off the coast of the Yucatan Peninsula this evening, and continue moving into southern Gulf of Mexico on Friday. Grace is expected to make a second landfall on the mainland coast of Mexico late Friday or early Saturday. Re-intensification is likely after the center emerges offshore into the Gulf of Mexico. Grace is forecast to be a hurricane when it makes its second landfall on the mainland coast of Mexico late Friday or early Saturday. Rapid weakening is expected after Grace moves inland over central Mexico. Yesterday, gusty winds of 35 to 42 kt (65 km/h-77 km/h) were reported in western Cuba in association with Grace. 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 29.7N 71.4W at 19/2100 UTC or 390 nm SSE of Cape Hatteras North Carolina moving W at 9 kt. Estimated minimum central pressure is 997 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Peak seas are currently 25 ft. Numerous moderate isolated strong convection is within 90 nm SW and 30 nm NE semicircles of center. On the forecast track, the center of Henri will remain well offshore of the east coast of the United States over the next couple of days, but it is forecast to be near southern New England on Sunday and Monday. Little change in strength is expected during the next 12 to 24 hours, but Henri is forecast to intensify into a hurricane by Friday night with additional strengthening expected this weekend. Swells generated by Henri should continue to affect Bermuda during the next day or so. Swells are expected to increase across much of the east coast of the U.S. and Atlantic Canada later this week and this weekend. These swells could cause life-threatening surf and rip current conditions. 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 tropical wave is along 29W from 21N southward, moving W at 10-15 kt. Scattered moderate convection is noted mainly ahead of the wave axis from 09N to 15N between 29W and 35W. A tropical wave is along 39W/40W from 21N southward, moving W at 10-15 kt. Scattered moderate convection is on either side of the wave axis from 06N to 12N between 35W and 45W. A tropical wave is along 59W/60W from 21N southward, moving W at around 15 kt. The wave is generating scattered showers and thunderstorms mainly over the Windward Islands and the eastern Caribbean E of 65W. Moisture associated with this wave will continue to impact the eastern Caribbean and parts of the Lesser Antilles tonight and Fri. A tropical wave is along 72W extending from Hispaniola to western Venezuela. It is moving W at around 10-15 kt. The wave is likely enhancing some convective activity over western Venezuela, including lake Maracaibo. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Mauritania near 17N16W to 13N29W to 09N46W. The ITCZ then extends from 09N46W to 09N57W. In addition to the convection associated with the tropical waves, scattered moderate convection is from 11N to 16N east of 20W. ...GULF OF MEXICO... Refer to the Special Features section above for details on Tropical Storm Grace. The most recent scatterometer data show storm force winds just N of the Yucatan peninsula to about 23N, with fresh to strong winds associated with the cyclonic circulation of Grace roughly covering the waters from 20N-25N between 88W-92W. Seas are 10-15 ft in this area of high winds. Gentle to moderate return flow is noted over the NW Gulf, with similar wind speeds elsewhere across the remainder of the Gulf region under the influence of 1020 mb high pressure located over the NE Gulf. Outside of the influence of Grace, seas are in the 3-5 ft range, except 1-3 ft over the NE Gulf. For the forecast, conditions associated with Grace will affect the Yucatan channel through tonight, and the region N of the Yucatan Peninsula and the SW Gulf, including the Bay of Campeche, through Sat. Winds and seas will gradually diminish across the western Gulf late Sat into Sun. High pressure will build in the wake of Grace and prevail through early next week. ...CARIBBEAN SEA... Refer to the Special Features section above for details on continuing impacts from Tropical Storm Grace over the NW Caribbean. Fresh to strong SE winds are still affecting the Caribbean waters W of 84W, with an area of 12-14 ft seas between Cozumel and Cancun, and 8-12 ft N of 10N W of 84W, including the Yucatan Channel. In the E and Central Caribbean, moderate to fresh trades prevail with 4-7 ft seas, except in the SW Caribbean where seas are 2-4 ft. Scattered to numerous showers and thunderstorms are noted over Central America, particularly over Nicaragua. Similar convective activity is seen over norther Colombia. For the forecast, Grace will continue to move west of the area this evening, with marine conditions gradually improving. Otherwise, moderate to fresh trade winds will dominate elsewhere, except for locally fresh to strong winds in the Gulf of Honduras tonight. ...ATLANTIC OCEAN... Refer to the Special Features section above for details on Tropical Storm Henri. Three tropical waves are moving westward between the W coast of Africa and the Lesser Antilles. Please, see Tropical Waves section for details. E of Henri, the Atlantic forecast waters are dominated by a 1023 mb high pressure centered near new. Under the influence of this system, mainly gentle to moderate ne-E winds are noted S of 30N and E of 60W. Winds increase to moderate to fresh near the northern end of the tropical wave located along 59W/60W, and N of 23N E of 18W to the W coast of Africa, including the Canary Islands. Seas of 6-7 ft are related to these winds. For the forecast, Henri will move N of area on Fri, and strengthen to a hurricane near 31.9N 72.9W by Fri evening. Otherwise, moderate to fresh E to SE winds will prevail E and across the Bahamas Fri through Mon, except for fresh to locally strong winds at night N of Hispaniola and the approaches to the Windward Passage. $$ GR