000 AXNT20 KNHC 251000 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Wed Oct 25 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 0900 UTC. ...SPECIAL FEATURES... Hurricane Tammy is centered near 25.6N 60.2W at 25/0900 UTC or 460 nm SSE of Bermuda, moving NE at 9 kt. Estimated minimum central pressure is 969 mb. Maximum sustained wind speed is 85 kt with gusts to 105 kt. Peak seas near the center are estimated at 27 ft. Numerous strong convection is noted within 150 nm of the center in the east semicircle and 120 nm in the west. Scattered moderate convection also extends out well to the NE of the center, just southeast of a stationary front, which is situated to the north of Tammy. A northward turn is expected later today, followed by a slower northwestward motion on Thursday and Friday. Some additional strengthening is likely this morning, followed by weakening through late this week. Tammy is forecast to become a powerful post-tropical cyclone tonight. Swells generated by Tammy will continue to affect portions of the Leeward Islands, the British and U.S. Virgin Islands, and Puerto Rico during the next couple of days. These swells are likely to cause life- threatening surf and rip current conditions. 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 latest Tammy NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Western Atlantic Very Rough Seas: The tightening pressure gradient between strong high pressure of 1030 mb over the east coast of United States and Hurricane Tammy will support a large area of strong to near-gale force NE winds and very rough seas of 12 to 17 ft across much of the area from 22N to 31N, between the east coast of Florida and 60W, through Friday. Mariners should either seek to avoid this region, or use extreme caution in this area, depending on your vessel type and cargo. 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 more details. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic through the coast of Guinea near 10N13W, then continues westward to near 07N30W. The ITCZ extends from 07N30W to 10N40W, then continues west of a surface trough from 09N46W to 11N57W. The surface trough extends from 14N42W to 07N43W. Scattered moderate to isolated strong convection is noted within 310 nm of these features. ...GULF OF MEXICO... High pressure of 1030 mb over the east coast of United States extends ridging into the Gulf of Mexico bringing dry conditions. Under the influence of this high pressure, fresh E to SE winds and seas of 4 to 7 ft prevail across the Gulf of Mexico, except for the eastern Gulf and the Straits of Florida where strong winds are found. For the forecast, high pressure north of the area will support moderate to fresh winds, locally strong in the E Gulf, through the remainder of the week. ...CARIBBEAN SEA... Divergence aloft is leading to scattered moderate convection in portions of the NW Caribbean from 15N to 19N, W of 80W. Scattered moderate convection is along noted within 90 nm of the Colombian coast, due to the eastern extension of the east Pacific monsoon trough. Continental high pressure over the United States is building southward toward the northwest Caribbean, and this is leading to increasing NE winds in the passages and lees of the Greater Antilles. Fresh to locally strong winds and seas of 5 to 7 ft, aided in some areas by long period swell from Hurricane Tammy to the north, are present in these areas. Elsewhere, gentle or lighter winds and seas of 2 to 3 ft are present. For the forecast, fresh to occasionally strong winds will prevail in the NW and north-central Caribbean through the week. Gentle winds will prevail elsewhere. ...ATLANTIC OCEAN... Please read the Special Features section at the beginning about Hurricane Tammy as well as rough seas that are developing over much of the western basin to the W of Hurricane Tammy. Aside from the impacts from these two features, to the E of 55W, high pressure of 1024 mb centered near 31N28W is dominant. Gentle to moderate winds prevail across the basin east of 55W with seas 5 to 7 ft. Locally fresh NE winds are occurring offshore Africa between the Cabo Verde and Canary Islands. For the forecast W of 55W, Hurricane Tammy is near 25.6N 60.2W at 5 AM EDT, and is moving northeast at 9 kt. Maximum sustained winds are 85 kt with gusts to 105 kt, and the minimum central pressure is 969 mb. Tammy will move to 27.0N 59.4W this afternoon, then become extratropical and move to 28.9N 59.3W Thu morning. Tammy will reach 30.0N 60.4W Thu afternoon, then weaken near 30.6N 61.6W Fri morning. Tammy will start to move N of the area, to the SE of Bermuda, Fri afternoon. A stationary front from 31N55W to the central Bahamas will dissipate today, but the gradient between Tammy and the decaying front combined with high pressure building in from the N and W will lead to an increasingly broad area of strong NE winds and rough seas across much of the area this week, mainly W of where the frontal boundary currently resides. $$ KONARIK