000 AXNT20 KNHC 211630 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Aug 21 2022 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 1610 UTC. ...TROPICAL WAVES... An eastern Atlantic tropical wave extends its axis along 25/26W from 09N-22N, moving west at 15 kt. Scattered moderate convection is noted within 180 nm W and 60 nm E of the wave axis from 14N-18N. Scattered showers are within 300 nm W of the wave axis from 08N-12N. Recent altimeter data near this wave show seas of 7-8 ft from 06N-15N between 22W-28W. This system has a low chance of tropical cyclone development within the next five days as it continues moving westward to west-northwestward at a similar forward speed. A central Atlantic tropical wave extends its axis along 45/46W from 07N-21N, moving west at 15 to 20 kt. Scattered moderate convection is noted within 60 nm of the wave axis from 07.5N to 09.5N, near where the wave axis intersects the monsoon trough. A central Caribbean tropical wave extends its axis along 75W from eastern Cuba to central Colombia, moving west at 10 to 15 kt. Scattered showers and tstorms between Jamaica and the Windward Passage are being enhanced by an upper-level low located N of the southeast Bahamas. Numerous moderate scattered strong convection located west of the wave axis, in the southwest Caribbean S of 12N between 75.5W-82W, is mainly due to the east Pacific monsoon trough. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic through the coast of Mauritania near 19.5N16.5W to the Cabo Verde Islands near 15N24.5W to 08.5N40W to 08N47W. The ITCZ continues from 08N47W to 07N55W to 11N61W. Scattered moderate and isolated strong convection is noted along and south of the monsoon trough from 04N-10N between 33.5W-44W. Similar convection is noted within 60 nm either side of the ITCZ between 57.5W-62W from 08N-12N. GULF OF MEXICO... The remnants of PTC Four have dissipated more than 120 nm inland from the coastline, along the Texas/Mexico border. However, some scattered showers and isolated tstorms are noted offshore the Texas and Louisiana coasts, due to the high amount of water vapor in the low to mid levels, as seen in CIRA LPW imagery. Abundant cloud cover with isolated showers are noted elsewhere over the northern Gulf, north of 28N between SE Louisiana and Destin, Florida. Deep-layered ridging extends from west to east across the northern Gulf of Mexico. At the surface, this ridge runs along 30N. A 1020 mb high pressure is analyzed near Apalachicola, Florida. Upper- level troughing prevails over the Yucatan and south-central Gulf. This, combined with a weak surface trough to the W of South Florida, is triggering isolated showers and tstorms from 23N-26.5N between 83W-87.5W. A recent ASCAT satellite wind data pass shows moderate E winds in the Straits of Florida, where seas are likely 3-4 ft. Moderate to locally fresh SE-SSE winds and seas of 5-6 ft are occurring off the coasts of Texas and northeastern Mexico. NOAA buoy 42020 near 27.0N 96.7W, which had been reporting seas of 7-8 ft earlier this morning, is now reporting seas of 6 ft. Light to gentle anticyclonic winds prevail over the NE Gulf near the high pressure center, with seas 1-2 ft. For the forecast, winds and seas continue to diminish over the northwest Gulf as high pressure builds across the northern Gulf. The weak ridging will prevail over the Gulf through the forecast period, leading to gentle to moderate winds and slight seas. CARIBBEAN SEA... Refer to the tropical waves section above for details on the tropical wave moving across the basin and on the convection in the SW Caribbean associated with the east Pacific monsoon trough. Upper-level troughing is present over the Yucatan Peninsula and far NW Caribbean, enhancing isolated thunderstorms between the Cayman Islands and the Yucatan Peninsula. Another cluster of scattered thunderstorms is located from 14N-16N between 77W-82W. An upper-level low located N of the southeast Bahamas extends an upper-level trough southward to near Hispaniola. Upper-level diffluence to the south of Hispaniola is enhancing a cluster of scattered moderate convection from 15N-18N between 66W-72W. Scattered showers and isolated tstorms in the far SW Caribbean, south of 13N and east of 64.5W, are related to the ITCZ. A recent ASCAT pass shows fresh to locally strong E winds just S of Hispaniola from 16.5N-18N between 71W-73W. Moderate or weaker winds prevail across much of the remainder of the basin, except for locally fresh NE winds in the lee of Cuba between 78W-81W. Buoy and altimeter data from the past few hours indicate that seas are 4-6 ft across the central Caribbean. Seas of 3-4 ft prevail elsewhere, except likely 2-3 ft in the Gulf of Honduras. For the forecast, surface ridging north of the area will continue to support moderate to fresh trade winds in the eastern and central Caribbean through the forecast period, while gentle to moderate winds will prevail across the western Caribbean. Fresh to locally strong NE winds are expected across the Windward Passage tonight. ATLANTIC OCEAN... An upper-level low centered N of the southeast Bahamas near 25N72W is inducing scattered thunderstorms from 25N-30N between 64W-74W. Another upper-level low is centered farther east, near 24N57W. A surface trough is in the same area, extending along 57W from 23N-31N. Scattered showers and isolated tstorms are noted from 22N-28N between 53W-59W. A surface ridge extends WSW from a 1023 mb high pressure centered near 32N68W to northern Florida. Over the western Atlantic, ASCAT shows gentle winds north of 27N with moderate trade winds to the south of 27N. An altimeter pass from this morning at 21/1030 UTC along 75/76W observed seas 2-3 ft north of 28N, and 4-5 ft to the south, with up to 6 ft in the Windward Passage. Seas are also likely 5-6 ft to the east of the southeast Bahamas. In the eastern half of the Atlantic, broad ridging prevails to the north of the tropical waves, with mostly moderate trade winds and 4-7 ft seas. The exception is the far NE part of the area, between the Canary Islands and the coast of Morocco, where fresh to locally strong N to NE winds are occurring along with seas of 6 to 9 ft. For the forecast west of 55W, the subtropical surface ridge extending from Bermuda to northern Florida will support moderate to fresh easterly winds south of 22N through the early part of this week. A weak surface trough will move westward from 65W to 75W on Mon. The trough will weaken the ridge, allowing winds to diminish by mid week. $$ Hagen