000 AXNT20 KNHC 280453 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Sat Oct 28 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 0435 UTC. ...SPECIAL FEATURES... Tropical Storm Tammy is near 32.7N 61.3W at 11 PM EDT, and is moving north-northwest at 4 kt. Maximum sustained winds are 50 kt with gusts to 60 kt, and the minimum central pressure is 991 mb. Peak seas are 24 ft. Sheared Tammy is producing scattered moderate convection over the northern quadrant. A turn toward the north and northeast is expected through early Saturday, followed by a faster eastward to east-southeastward motion on Sunday and Monday. On the forecast track, Tammy will move away from Bermuda on Saturday. Weakening is expected during the next few days, and Tammy is forecast to become a post-tropical remnant low early next week. 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. Western Atlantic Rough Seas: A subtropical ridge over the Carolinas combines with a low level trough than extends from S of Tammy to the NE Caribbean to produce a large area of fresh to locally strong winds and very high seas between Tammy and the Bahamas. A large area of 12-13 ft seas is just northeast of the Bahamas and the Turks and Caicos Islands. These associated high seas between Tammy and the Bahamas will subside through Sun, decreasing below 8 ft late Mon. Mariners should either avoid this region or use extreme caution in this area, depending on your vessel type and cargo. Hazardous surf and rip currents are also anticipated along the coast of central Florida, the Bahamas, Greater Antilles and the northern Leeward Islands. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at the website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the Offshore Waters Forecast at https://www.nhc.noaa.gov/marine/offshores.php for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic through the coast of Senegal near 15N17W and continues southwestward to 09N19W. The ITCZ extends from 09N19W to 04N33W to 05N47W. Scattered moderate to isolated strong convection is seen on satellite imagery from 04N to 14N and between 27W and 55W. The eastern North Pacific monsoon trough extends from Central America along the southern coast of Nicaragua at 11N84W to a 1008 mb low pressure near 11N78W to the coast of Colombia at 11N75W. Scattered moderate and isolated strong convection is noted south of 13N and between 75W and 80W. ...GULF OF MEXICO... An expansive 1023 mb high pressure over the Carolinas extends southwestward into the Gulf of Mexico. A dry airmass only supports a few patches of isolated, light showers dotting the Gulf waters. A recent scatterometer satellite pass captured fresh to strong easterly winds south of 25N and east of 95W. Seas in these waters are 6-8 ft, with the highest seas occurring in the eastern Bay of Campeche. Moderate or weaker winds and 4-6 ft seas prevail elsewhere. For the forecast, high pressure centered across the middle Atlantic coastal states will continue to support fresh to strong winds in the southeast and south central Gulf through early Sun. Mainly gentle NE winds are expected by Mon as the pressure gradient weakens and high pressure settles over the region. The next cold front is forecast to reach the NW Gulf on Mon. This front will bring gale force winds and quickly building seas over the western Gulf beginning Mon evening. The front will move SE through the entire basin by Wed afternoon. ...CARIBBEAN SEA... A surface trough is analyzed from Puerto Rico to northern Venezuela. Meanwhile, an active upper level trough stretches from the Windward Passage to Central America. These features combined with plenty of tropical moisture result in numerous showers and isolated thunderstorms east of the surface trough, affecting Puerto Rico and the Virgin Islands with very heavy rainfall. Flash flooding is already occurring in Puerto Rico. The weather pattern will remain very conducive for the development of showers and thunderstorms across the region during the weekend and into early next week. The remainder of the Caribbean is under the influence of the 1023 mb high pressure system over the Carolinas. No deep convection is noted in the NW Caribbean Sea and most of the central portion of the basin. The pressure gradient between the aforementioned ridge and lower pressures in the deep tropics support fresh to locally strong NE winds north of 16N and west of 75W. The strongest winds are found in the lee of Cuba. Seas in these waters are 5-8 ft. Fresh to strong southerly winds and seas of 6-9 ft are evident in the eastern Caribbean due to the strong storms in the area and the large region of northerly swell associated with Tammy. Moderate or weaker winds and wave heights in the 3-5 ft range are present in the rest of the Caribbean. For the forecast, strong high pressure centered over the middle Atlantic U.S. coast is combining with elongated low pressure extending from the W central Atlantic across the NE Caribbean will support fresh to strong NE to E winds in the NW and north-central Caribbean, including the Windward Passage through the weekend. Gentle winds prevail elsewhere. Large N-NE swell across the W Atlantic will continue to move through the NE Caribbean Passages through Sun. Broad low pressure is expected to develop over the W central Caribbean by Sun and move slowly northward and into the Bahamas through Tue. ...ATLANTIC OCEAN... Please read the Special Features section above for more information on Tropical Storm Tammy east of Bermuda, and rough seas across the SW North Atlantic. The central and eastern tropical Atlantic are under the influence of a 1022 mb subtropical ridge positioned near 30N35W. The pressure gradient between the aforementioned ridge and lower pressures in the deep tropics result in fresh to locally strong easterly winds south of 22N, along with seas of 6-9 ft. Farther east, a broad storm system west of Ireland is producing a large region of swell that is entering the northeast waters of the tropical Atlantic, resulting in seas of 8-11 ft north of the Canary Islands and east of 25W. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast W of 55W, Tropical Storm Tammy is near 32.7N 61.3W at 11 PM EDT, and is moving north-northwest at 4 kt. Maximum sustained winds are 50 kt with gusts to 60 kt, and the minimum central pressure is 991 mb. Tammy will move to 32.9N 60.3W Sat morning, 32.6N 57.9W Sat evening, 31.9N 55.0W Sun morning, 30.5N 52.7W Sun evening, weaken to a tropical depression near 29.1N 51.6W Mon morning, and become a remnant low and move to 28.2N 51.6W Mon evening. Tammy will change little in intensity as it moves to 28.1N 52.2W by late Tue. High pressure across the middle Atlantic coastal states is combining with a low level trough than extends from S of Tammy to the NE Caribbean to produce a large area of fresh to locally strong winds, with very high seas between Tammy and the Bahamas. These high seas will slowly subside Sat through Sun. Elongated low pressure will develop across the SE Bahamas Sun and gradually drift NW through Tue. $$ Delgado