000 AXNT20 KNHC 121100 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu Oct 12 2023 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 1000 UTC. ...SPECIAL FEATURES... Tropical Depression Sean is near 12.5N 36.7W at 0900 UTC, or about 885 nm WSW of the Cabo Verde Islands, moving WNW at 10 kt. Maximum sustained winds are 30 kt with gusts to 40 kt. Minimum central pressure is 1007 mb. Scattered moderate to strong convection extends from 10.5N to 14N between 32.5W and 36W, and remains sheared to the east of southeast of the center by 60 to 90 nm, Scattered moderate isolated strong convection is also noted west of Sean from 11N to 14N between 39.5W and 44W. Peak seas are estimated near 11 ft. A west- northwestward or northwestward track at a slightly slower forward speed is expected during the next few days. Little change in strength is forecast during the next few days and Sean is expected to remain under strong vertical wind shear. Northern Gulf of Mexico and Western Atlantic Ocean Gale Warning: Low pressure of 997 mb is centered over the north-central Gulf of Mexico near 29.5N88W, as of 0600 UTC. A cold front extends from the low southwestward to 26N91W, and a surface trough continues to offshore of Veracruz, Mexico. A warm front extends from the low eastward along 29.5N and across northern Florida. NE to E winds across the coastal waters NW through NE of the low center and warm front have diminished below gale force in the past few hours. However, frequent gusts to gale force continue across the nearshore coastal waters from the Florida Panhandle to central Louisiana, and a gale warning remains in effect through sunrise. Numerous moderate to scattered strong convection occurring overnight across the NE Gulf of Mexico has shifted inland across NE Florida and extends into the adjacent Atlantic. Narrow lines of moderate to strong thunderstorms persist over the Gulf waters, from the Florida Panhandle and Big Bend region southwestward to 89W. Strong SW winds of 20 to 30 kt are occurring E of the cold front, and north of 26N to the warm front. These strong winds have generated very large seas overnight, with recent altimeter data measuring seas as high as 14 ft off of the mouth of the Mississippi River, while a large area of 8 to 10 ft and higher cover most of the waters N of 27N between 86W and 92W. The low pressure system is expected to move inland over northern Florida by this morning, with the winds in the Gulf gradually diminishing through the afternoon. The low pressure along the frontal system will move into the western Atlantic today, and gale force winds should develop north of 30N and east of 75W by late afternoon today, then continue to shift eastward tonight, and across the northeast offshore waters Fri through early Sat. Gale-force winds are forecast to affect the northern offshore waters N of 30N this evening and tonight and N of 27N Fri through Fri night. Strong thunderstorms and large and confused seas are expected with this frontal system. As the system moves E, gale force winds may occur as far south of 27N between 55W and 65W on Fri. Seas will build to 12 to 18 ft Fri east of 65W and north of 26N. Please read the latest High Seas Forecast issued by the National Hurricane Center at the website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for details on Sean and the gales in the Gulf of Mexico and Atlantic. ...TROPICAL WAVES... An eastern Atlantic tropical wave has its axis along 22W from 03N to 17N, moving westward 10 kt. A broad 1010 mb low (Invest AL94) is located on the wave near 09N. Scattered moderate isolated strong convection is within 150 nm NE of the low from 09N to 13N between 17W and 22W. This activity remains disorganized. Environmental conditions appear conducive for some slow development over the next few days. This system should move westward across the eastern and central tropical Atlantic through early next week. The system has a low chance of tropical cyclone formation within the next 48 hours. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through the coast of Senegal near 14N17W to Invest AL94 near 09N23W to 10N30W. The ITCZ extends from 08N45W to 07.5N47W to 11N58W. Aside from the convection mentioned in the sections above associated with Sean and AL94, widely scattered moderate convection is noted from 02.5N to 07N between 09W and 31W. GULF OF MEXICO... Please read the Special Features section for details about the ongoing gale event over the north-central and northeastern Gulf of Mexico. Outside of the gale area, strong S to SW winds prevail over the eastern Gulf, to the east of the cold front, north of 26N, where seas are 7 to 11 ft. Fresh to locally strong S winds are over the SE Gulf, south of 26N to the Yucatan Channel and Straits of Florida, with seas 6 to 7 ft. To the west of the cold front, south of the Louisiana coast, northerly winds are still strong with seas slowly subsiding from a peak of 10-15 ft overnight, now at 6 t0 10 ft. Gentle to moderate winds and 3 to 5 ft seas are found over the southwestern Gulf of Mexico. Isolated thunderstorms are over the SW Gulf of Mexico offshore of Veracruz. For the forecast, NE gales have ended N of the low and front early this morning. The low and frontal system will move eastward and inland across N Florida this morning, accompanied by scattered to numerous strong thunderstorms and strong winds. Winds and seas will gradually diminish this afternoon through evening. High pressure across the Atlantic will build modestly westward into the eastern Gulf Fri through early Sat, before the next cold front moves into the NW Gulf Sat morning and across the entire basin by Sun evening. CARIBBEAN SEA... Mid- to upper-level anti-cyclonic flow prevails across most of the basin, which is leading to subsidence and relatively dry conditions. The exception is the far SW Caribbean, where scattered showers and isolated thunderstorms are found south of 13N. Fresh trades prevail across the central Caribbean between 67W and 76W, locally strong near the coasts of NW Venezuela and NE Colombia. A large area of fresh to strong SE winds currently covers the NW Caribbean. Seas are 5-7 ft across the central Caribbean and 5-8 ft in the NW Caribbean. Moderate winds with 4-5 ft seas are in the far eastern Caribbean. For the forecast, a weak ridge persists just N of the basin to the NW Bahamas. Moderate to fresh trade winds across the eastern and central Caribbean will diminish to gentle to moderate early Fri and prevail through Mon night as the high pressure shifts eastward. Fresh to strong SE to S winds in the Gulf of Honduras and NW Caribbean will continue through Fri night. A cold front will sink S-SE across the western Atlantic over the weekend and act to maintain the weak trade wind flow across the basin. ATLANTIC OCEAN... Please read the Special Features section for details about Tropical Depression Sean and on an upcoming western Atlantic gale event. Please read the Tropical Waves section for details about Invest-AL94 and the associated tropical wave. A cold front extends from near 31N46W to 26N53W to 29N64W, where it transitions to a warm front continuing westward to NE Florida along 29.5N. To the south, a weak ridge extends from 1014 mb high pressure near 23N62W to the NW Bahamas. Convection is increasing across the NW waters near the warm front, where satellite imagery shows scattered to locally numerous moderate to strong convection moving off the coast of northern Florida, and across the waters from 28N to 31N eastward to 75W. Fresh to strong southerly winds are expanding from offshore of NE Florida, southward to near Cape Canaveral, while fresh S winds now extends across the SE Florida coastal waters N of Miami. Seas are 5 offshore of Cage Canaveral to 9 ft off of Jacksonville, and will build quickly later this morning as winds increase ahead of the approaching low pressure system in the Gulf. Gentle to moderate SE to S winds prevail across much of the Atlantic north of 22N W of 70W, where seas are 4 to 5 ft. Farther east, a warm front extends from 31N40W northeastward to low pressure across the central Atlantic. Upper-level diffluence is supporting scattered moderate to strong convection from 24N to 31N between 37W and 50W. Similar convection is seen within 60 nm either side of a line extending from 31N25W to 26.5N38W. Moderate to fresh SW winds and 6 to 7 ft seas are likely occurring from 26N to 31N between 44W and 56W. A 1015 mb high pressure is centered near 23N33W, to the north of T.D. Sean. For the forecast W of 55W, the 997 mb low pressure along the front in the N Gulf of Mexico is expected to move eastward across N Florida this morning, then continue eastward and emerge across the W Atlc, bringing strong to near gale force winds east of northern and central Florida today, then move E of 75W tonight, and move eastward across the NE waters Fri through early Sat. Gale force winds are forecast to affect the northern offshore waters N of 30N this evening and tonight and N of 27N Fri through Fri night. Scattered showers and thunderstorms and high seas are expected with this frontal system. Weak high pressure will prevail S of 24N through the weekend. $$ Stripling