586 AXNT20 KNHC 081142 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu Jul 8 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 1130 UTC. ...SPECIAL FEATURES... Tropical Storm Elsa is located over southern South Carolina near 32.4N 81.3W at 08/0900 UTC or about 90 mi WNW of Charleston, South Carolina and about 210 mi WSW of Wilmington, North Carolina, moving NNE at 14 kt. Maximum sustained wind speed is 35 kt with gusts to 45 kt. The estimated minimum central pressure is 1007 mb. Satellite imagery shows that the cyclone is sheared, with a large area of scattered moderate to strong convection displaced far to the northeast of its center. This convection is noted from 31N to 36N between 76W-82W, which includes the northern portion of South Carolina and most of the eastern half of North Carolina. On the current forecast track, Elsa will move over South Carolina and North Carolina today, pass near the eastern Mid- Atlantic states by tonight, and move near or over the northeastern United States on Fri and Fri night. The system should move over Atlantic Canada by Fri night and Sat. Elsa is forecast to become a post-tropical cyclone Fri night or Sat. Elsa is expected to produce storm totals of 3 to 5 inches with isolated maximum amounts up to 8 inches are likely today across portions of South Carolina, which may result in limited flash and urban flooding. Elsa is also expected to produce 2 to 4 inches of rain with isolated totals up to 6 inches possible across central and eastern North Carolina into southeastern Virginia and from the Mid-Atlantic into New England through Fri. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml, Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml, and the High Seas Forecast issued by the NWS Ocean Prediction Center at https://ocean.weather.gov/shtml/NFDHSFAT1.php for more details. For marine information within 60 nm of the coast, please see products from your local NWS Weather Forecast Office at www.weather.gov. Gale warning E of 35W: The pressure gradient between high pressure of 1029 mb located about 400 nm east-northeast of the Azores and lower pressures over Africa is resulting in strong to gale-force north to northeast winds north of 20N and east of 25W, including the Canary Islands. Meteo-France has issued a Gale Warning for Agadir from 08/12 UTC to 09/00 UTC. The forecast calls for north winds Force 8 in the Beaufort Wind scale with gusts. For more details, refer to the Meteo-France High Seas Forecast listed in their website: www.meteofrance.com /previsions- meteo- marine/ bulletin/grandlarge/metarea2. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 23W south of 11N southward, moving westward at 10-15 kt. This wave is surrounded by a moist atmospheric environment. Scattered moderate convection is within 300 nm W of the wave axis from 04N-11N. Another eastern Atlantic tropical wave, with a larger amplitude, has its axis extending from 23N34W to 15N35W and to 04N36W. It is moving westward near 15 kt. A small area of scattered moderate convective is ahead of the wave primarily associated to the ITCZ within 30 nm of line from 06N36W to 05N39W. A central Atlantic tropical wave has its axis along 56W south of 14N, moving westward at 15-20 kt. Scattered moderate convection is increasing within 180 nm W of the wave from 08N-10N and within 120 nm E of the wave from 09N to 10N. The leading edge of this convection is reach the coast of Brazil near the French Guiana border. A tropical wave over the Caribbean has its axis along 70W south of 13N. It is moving westward near 15 kt. Isolated showers are possible near this wave over the Caribbean. Scattered moderate convection is over sections of central Venezuela. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of Guinea-Bissau near 11N15W to 09N21W and to 08N32W. A segment of the ITCZ is analyzed from 06N39W to 34N51W. Scattered moderate convection is within 60 nm south of the trough between 15W-20W and within 60 nm S of the ITCZ between 39W-45W. Similar convection is well S of the monsoon trough from 02N to 06N E of 16W to just inland the coast of Africa. GULF OF MEXICO... An upper-level low is over southern Texas. A trough extends from the low to over northern Mexico. At the surface, a 1008 mb low is analyzed over southern Texas. A trough is just inland the Texas coast. The combination of divergence east of the upper-level trough along with the aforementioned surface features is leading to large clusters of scattered moderate to convection over the NW Gulf from 23N to 30N and W of 92W. Some of this activity may produce gusty winds. It will continue throughout and into the evening. Latest surface observations and overnight ASCAT data indicate moderate to fresh southeast winds in this area of convection. A diurnal surface trough moved off the Yucatan Peninsula during the overnight hours and into the eastern part of the SW Gulf to a position from 24N90W to 19N92W. Scattered moderate convection is west of the trough to 96W and from 19N to 21N. Gentle to moderate southeast winds continue across most of the Gulf, except in the northeast section of the basin where gentle southwest to west winds remain in the wake of Tropical Storm Elsa. Seas are generally 3-6 ft throughout the Gulf. For the forecast: High pressure from the Atlantic will build westward across the area through the next few days, with relatively quiet conditions expected. The Yucatan Peninsula trough will shift westward to the SW Gulf during the mornings through the weekend followed by fresh to strong southeast winds. Scattered to numerous showers and thunderstorms over the NW Gulf are expected to continue through this evening. CARIBBEAN SEA... Near-gale force east winds were detected by an overnight ASCAT pass over the Gulf of Venezuela. Strong trades continue in the south central Caribbean within 120 nm of the coast of Colombia, with resulting wave heights of 8-11 ft as was suggest by overnight altimeter data over that area of the Caribbean and by NOAA buoy 42058 at 15N75W. Strong trades are also occurring in the Gulf of Honduras with wave heights of 6-8 ft. Moderate to fresh trades prevail over the remainder of the Caribbean. Wave heights range from 5-8 ft in the eastern Caribbean, 6-9 ft in the north central Caribbean, 7-10 ft in a northeast swell in SW Caribbean, and 4-6 ft in the NW Caribbean and Windward Passage. For the forecast: Widespread strong trades will continue in the south-central Caribbean into Fri night. These winds may reach near gale force Thu through Fri night. Fresh to strong winds will pulse at night in the Gulf of Honduras through Sun. ATLANTIC OCEAN... The Bermuda-Azores high dominates the Atlantic forecast waters. Of note, during the summer, the Gulf of Mexico and the Caribbean Sea are dominated by the Bermuda-Azores high, when it is at its westernmost position. Circulation around the high results in southerly winds over the Gulf of Mexico and easterly winds over the Caribbean Sea. These winds bring warm, moist air from the ocean over land. For us in South Florida, this pattern brings with it the rainy season and high dewpoints. The latest surface analysis valid at 0600 UTC depicts a 1029 mb Azores high near 36N35W, with its associated ridge stretching westward to near 75W, then west-southwest to South Florida. An upper trough extends from 31N66W to 28N70W. Scattered moderate convection is within 60 nm of the trough. Isolated showers and thunderstorms are north of 26N W of 70W. An overnight ASCAT pass picked up on fresh strong east winds between the southeastern Bahamas and Hispaniola, where wave heights are 5-7 ft. These winds will continue to pulse through early next week. An area of fresh trades due to a tight pressure gradient between the high pressure ridge over the northern part of the are and relatively lower pressure in the tropics is over the area defined from 10N to 22N east of 52W. Gentle to moderate trades are present elsewhere, except for light winds near and along the high pressure ridge between 55W-67W. Wave heights are in the range of 4-6 ft W of 70W, and 5-7 ft over the remainder of the basin except for higher wave heights of 6-8 ft due to a northeast swell east of the Lesser Antilles from 11N to 20N between 57W-61W. This swell will subside by early this evening. For the forecast W of 65W: Fresh to strong south to southwest winds over the far northwest part of the area will lift north of the area this morning as Tropical Storm Elsa, currently over South Carolina, continues to pull away from the region. High pressure will then build westward across the area through Sun night. East winds will pulse to fresh to strong speeds at night between the southeastern Bahamas and Hispaniola through the period. $$ Aguirre