000 AXNT20 KNHC 290540 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Sun Oct 29 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 0000 UTC surface analysis and satellite imagery through 0515 UTC. ...SPECIAL FEATURES... Tropical Storm Tammy is near 32.6N 55.2W at 11 PM EDT, and is moving east-southeast at 15 kt. Maximum sustained winds are 35 kt with gusts to 45 kt, and the minimum central pressure is 1000 mb. Peak seas are 18 ft. Strong westerly shear is displacing the convection well east of the center. The cyclone is expected to gradually turn southward before dissipating by the middle part of next week. Additional weakening is expected, and Tammy is forecast to become a post- tropical remnant low as soon as tomorrow. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Tammy NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Invest 96L: A 1007 mb low pressure is near 22N67W, or a couple hundred miles north of the Dominican Republic. Scattered moderate to isolated strong convection is noted from 18N to 26N and between 63W and 68W. The system is producing strong to near gale- force winds, especially over the northern semicircle. Seas in the area are 8-12 ft. The disturbance is showing signs of organization and a short-lived tropical depression or storm could form later today while the system moves west-northwestward. By Monday, however, strong upper-level winds and dry air should end the chances of further development. An Air Force reconnaissance aircraft is scheduled to investigate the system later today, if necessary. The chance of development over the next 48 hours is medium. Please read the latest Tropical Weather Outlook at hurricanes.gov for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the tropical Atlantic through the coast of Guinea-Bissau near 12N16W and continues southwestward to 06N23W. The ITCZ stretches from 06N23W to 06N40W to 08N59W. Scattered moderate convection is observed from 03N to 09N and between 20W and 25W. Scattered moderate to isolated strong convection is present north of the ITCZ to 16N between 35W and 60W, enhanced by an upper level trough and a surface trough along 45W. GULF OF MEXICO... The subtropical ridge off the SE United States continues to dominate the weather conditions across the Gulf of Mexico, suppressing the development of deep convection. A modest pressure gradient between the aforementioned high pressure system and lower pressures in the deep tropics support fresh to strong easterly winds, mainly south of 27N and east of 93W. Seas are 5-9 ft in these waters. The strongest winds and highest seas are occurring in the Florida Straits. Moderate or weaker winds and seas of 2-5 ft are present elsewhere. For the forecast, high pressure centered across the middle Atlantic coastal states will continue to support fresh to locally strong winds in the southeast and south central Gulf through Sun. Gentle NE winds are expected by Mon as the pressure gradient weakens and high pressure settles over the region. A strong cold front will enter the NW Gulf Mon morning, and move SE across the entire basin by Wed evening. This front will bring gale force winds and quickly building seas over the western Gulf beginning Mon thru Wed night. CARIBBEAN SEA... The eastern Pacific monsoon trough extends from the coast of Nicaragua to the central Caribbean Sea, followed by a surface trough to eastern Hispaniola. The cyclonic flow brings plenty of moisture northward, and along with divergence aloft, result in unsettled weather conditions to the east of the surface features described. Latest satellite imagery show scattered showers and isolated thunderstorms affecting the waters offshore Colombia, Puerto Rico and the Leeward Islands. These storms are also impacting the islands in the NE Caribbean, causing localized flooding. The weather pattern will continue to favor scattered showers and isolated thunderstorms through early next week. Dry air encompasses the NW Caribbean and Gulf of Honduras, resulting in only fast-moving, isolated light showers. The pressure gradient between the ridge off the SE United States and lower pressures in the deep tropics sustain fresh to strong NE-E winds in the NW Caribbean, Gulf of Honduras and Windward Passage. Seas are 4-7 ft in the areas described. The strongest winds are occurring in the lee of Cuba. Moderate to locally fresh southerly winds and seas of 4-7 ft are found in the eastern Caribbean. Elsewhere, light to gentle winds and slight to moderate seas prevail. For the forecast, a strong high pressure centered over the middle Atlantic U.S. coast is combining with surface trough across the Caribbean along 68W-69W and into the adjacent Atlantic to support fresh to locally strong NE to E winds in the NW Caribbean. This trough will shift W-NW through early next week, with winds diminishing across the NW Caribbean on Sun. Scattered to numerous strong thunderstorms occurring along and E of the trough will shift westward with the trough through Mon. Large N-NE swell across the W Atlantic will continue to move through the NE Caribbean Passages through Sun. A strong cold front will enter the NW Caribbean by mid week. ATLANTIC OCEAN... Please see the SPECIAL FEATURES section above for information on Tropical Storm Tammy located well east of Bermuda and on Invest 96L positioned north of the Dominican Republic. A 1021 mb high pressure system off the SE United States dominates the SW tropical Atlantic. The pressure gradient between the ridge and lower pressures in the deep tropics and Invest 96L sustain fresh to strong NE winds west of 70W. Seas in these waters are 8-12 ft, with the highest seas occurring off the central Bahamas. The central and eastern Atlantic are under the influence of a 1019 mb high pressure system near 28N40W. A cold front enters the tropical Atlantic near 31N30W to 29N35W to 31N40W. No deep convection is seen near the frontal boundary. Moderate to locally fresh westerly winds and seas of 6-8 ft are evident north of 28N and between 20W to 35W. The pressure gradient between the ridge and lower pressures in the deep tropics support moderate to locally strong easterly winds south of 22N and west of 35W. Wave heights in the area described are 7-9 ft. Farther east, moderate to locally fresh northerly winds and seas of 6-8 ft are found off the coast of Africa, mainly east of 22W. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast W of 55W, Tropical Storm Tammy is near 32.6N 55.2W at 11 PM EDT, and is moving east-southeast at 15 kt. Maximum sustained winds are 35 kt with gusts to 45 kt, and the minimum central pressure is 1000 mb. Tammy will weaken to a remnant low near 32.0N 52.0W Sun morning, move to 30.5N 48.3W Sun evening, 29.0N 46.0W Mon morning, 27.5N 45.5W Mon evening, 26.5N 46.0W Tue morning, and dissipate on Tue evening. High pressure across the middle Atlantic coastal states is combining with a low level trough than extends from S of Tammy to 1007 mb low pressure located just N of the Mona Passage to produce a large area of fresh to locally strong winds, with high seas between Tammy and the Bahamas. This system could become a short-lived tropical depression or storm over the next day or so. By Monday, upper- level winds are forecast to become too strong for further development as the system turns northward to the east of the northwestern Bahamas. These high seas will slowly subside through Mon. The low pressure is expected to move NW and parallel to the Bahamas Sun through Mon, accompanied by strong winds and very active weather. A strong cold front will enter the NW waters Wed morning. $$ DELGADO