000 AXNT20 KNHC 210539 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Thu Sep 21 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 0545 UTC. ...SPECIAL FEATURES... Hurricane Nigel is centered near 39.0N 50.4W at 21/0300 UTC or 480 nm SSE of Cape Race Newfoundland, moving NE at 22 kt. Estimated minimum central pressure is 973 mb. Maximum sustained wind speed is 80 kt with gusts to 100 kt. Peak seas N of our area are currently around 39 ft. Numerous moderate to strong convection is evident within 150 nm in the NE semicircle of Nigel. Hurricane Nigel is expected to accelerate northeastward over the next day or two. Weakening is forecast during the next couple of days, and Nigel is forecast to become a post-tropical cyclone by Friday. Swells generated by Nigel currently affecting Bermuda will gradually subside through Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. 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 Nigel NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Atlantic Gale Warning: The pressure gradient between low pressure that is expected to develop along a stationary front N of the Bahamas and high pressure over the southeastern U.S. will result in frequent wind gusts to gale force N of 30N and W of 75W starting Thu afternoon, then N of 29N and W of 76W by late Thu night. Seas with these winds are forecast to be 9 to 12 ft and could be locally higher. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2 for further details. ...TROPICAL WAVES... A tropical wave is in the far eastern Atlantic Ocean near 22W, moving W through the Cabo Verde Islands at 5 to 10 kt. Scattered moderate to strong convection is evident from 12N to 16N between 23W and 26W. A tropical wave in the central Atlantic is centered near 37W, from 18.5N southward, moving W at around 15 kt. Scattered moderate to isolated strong convection is evident from 03N to 17N between 32W and 40W. A western Atlantic tropical wave is near 51W, from 15N southward, moving W at 5 to 10 kt. No significant convection is depicted in association with this tropical wave. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends off the coast of Senegal near 16N17W to 9.5N31W to 10N50W. The ITCZ axis extends from 10N52W to 10N60W. Nearby significant convection is discussed in the TROPICAL WAVES section above. ...GULF OF MEXICO... A slowly dissipating stationary front extends from near Sarasota, Florida, to 28N87W. Scattered moderate convection is noted north and south of this boundary. Moderate to fresh SE winds are present N of the front, with seas up to 4 ft. A weak surface trough is noted in the eastern Bay of Campeche, with locally fresh NE winds. No significant convection is noted in association with the trough. Elsewhere, mainly gentle winds, with seas 1-3 ft prevail. For the forecast, high pressure will be in control of the weather pattern across the Gulf waters allowing for generally gentle to moderate east to southeast winds and slight seas, except pulsing to moderate to fresh offshore the western Yucatan Peninsula in the evenings. Developing low pressure east of Florida will tighten the pressure gradient over the NE Gulf bringing moderate to locally fresh NE winds across the NE Gulf Thu night into Fri. A frontal trough associated with the aforementioned low pressure will move across the southeastern Gulf and the Straits of Florida Thu night into Fri. ...CARIBBEAN SEA... A deep layer trough E of the Yucatan Peninsula is inducing scattered moderate convection in the NW Caribbean Sea. A weak pressure gradient sustains mainly moderate to fresh easterly trade winds in the central Caribbean. However, strong winds are occurring just off the N Colombia and NW Venezuelan coasts. Seas in the central Caribbean are in the range of 4-7 ft. Elsewhere, gentle to moderate winds and seas of 2-5 ft prevail. For the forecast, long period north to northeast swell moving through the Tropical N Atlantic waters and Caribbean passages will subside Thu. Moderate to fresh trade winds in the central Caribbean will change little through the next few days. Northeast to east trade winds will pulse to fresh to strong speeds offshore northern Colombia and northwest Venezuela during the afternoons and at night into early next week. ...ATLANTIC OCEAN... Please read the SPECIAL FEATURES section for details on Hurricane Nigel and on an Atlantic Gale Warning. In addition, please read the TROPICAL WAVES and MONSOON TROUGH/ITCZ sections for details on convection in the Atlantic Ocean. A stationary front extending from just south of Bermuda to 29N73W and to inland Florida near Daytona Beach, Florida. The combination of this front and a very sharp upper- level trough over its vicinity is leading to numerous moderate to strong convection from 24N to 31N between 71.5W and 74W and west of 79W. A surface trough extends from around 28N73W through the NW Bahamas, locally enhancing convection further. Moderate to fresh NE to E winds are N of the front. Another surface trough extends from 31N50W to 24N58W, but is not producing any convection. Otherwise, weak ridging dominates W of 50W. To the E, an upper level trough is producing a cluster of showers and thunderstorms near 19N48W. Moderate to fresh trades are evident from 17N to 27N between the coast of Africa and 55W between a ridge N of that area and three tropical waves along the monsoon trough/ITCZ. Locally strong winds are occurring off the coast of Western Sahara. Seas in the broad zone of tradewinds are 7-9 ft. Across the remainder of the basin, gentle to moderate winds and 4-7 ft seas prevail, except 6-9 ft seas in northerly swell related to Nigel N of 28N between 48W and 65W. For the forecast W of 55W, the aforementioned stationary front will lift northward on Fri as low pressure develops along it to the east of northern Florida, and where frequent gusts to gale force are possible Thu night into Fri. This non-tropical low pressure system could acquire some subtropical characteristics on Fri while it moves generally northward. In its wake, high pressure ridging will build from E to W just north of the forecast waters into early next week. $$ KRV