613 AXNT20 KNHC 281008 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Tropical Storm Tammy is centered near 33.0N 60.1W at 28/0900 UTC or 240 nm E of Bermuda, moving NE at 6 kt. Estimated minimum central pressure is 994 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Peak seas are 21 ft. Scattered moderate convection prevails over the NE quadrant. On the forecast track, Tammy will continue to move away from Bermuda today. Weakening is expected during the next few days, and Tammy is forecast to become a post-tropical remnant low early next week. Swells generated by Tammy will continue to affect Bermuda through tonight. These swells are likely to cause life- threatening surf and rip current conditions. Please consult products from your local weather office for details. 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 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 by 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 14N17W and continues southwestward to 13N19W. The ITCZ extends from 13N19W to 08N53W. Scattered moderate to isolated strong convection prevails from 04N to 12N and between 30W and 47W. The eastern North Pacific monsoon trough extends from Central America along the southern coast of Nicaragua at 11N84W to a 1007 mb low pressure near 11N81W to the coast of Colombia at 12N72W. Scattered moderate convection is noted south of 13N and between 73W and 84W. ...GULF OF MEXICO... A 1023 mb high pressure over the Carolinas extends southwestward into the Gulf of Mexico. A dry airmass prevails across the Gulf waters. Fresh to strong easterly winds are noted in latest scatterometer data 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. 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 late Wed. ...CARIBBEAN SEA... A surface trough is analyzed from the Mona Passage 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 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 to 7 ft are evident in the eastern Caribbean near convection. A large region of northerly swell associated with Tammy reaches the NE Caribbean waters including the Passages. 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 Caribbean, through this morning. 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 subtropical ridge anchored by a 1020 mb high near 29N42W. The pressure gradient between this ridge and lower pressures in the deep tropics result in fresh to strong easterly winds south of 22N, along with seas of 6-8 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 22W. Elsewhere, moderate or weaker winds and moderate seas are prevalent. For the forecast W of 55W, Tropical Storm Tammy will move to 33.0N 58.7W this afternoon, 32.6N 56.0W Sun morning, 31.7N 53.1W Sun afternoon, weaken to a remnant low near 30.4N 50.6W Mon morning, 28.9N 49.5W Mon afternoon, and 27.5N 50.8W Tue morning. Tammy will change little in intensity as it moves to 27.9N 53.1W by early Wed. 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 strong winds, with very high seas between Tammy and the Bahamas. These high seas will slowly subside through Sun. Elongated low pressure will develop across the SE Bahamas Sun and gradually drift NW through Tue. $$ ERA