000 AXNT20 KNHC 021040 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sat Sep 2 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... Gale Warning/Tropical Storm Warning: Post-Tropical Cyclone Idalia is centered near 31.7N 64.6W at 02/0900 UTC or 40 nm SSE of Bermuda, moving E at 5 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Numerous moderate to strong convection is noted north of the low from 32N to 35N between 60W and 65W. The 12 ft seas extend as far south as 26N between 61W and 73W. Moderate swell from Idalia is reaching Florida and the Bahamas. A gale warning is in effect for the Atlc offshore waters N of 29N between 62W and 68W. The post- tropical cyclone will move east today. A faster northeastward motion is forecast to begin on Sunday, and this motion should continue into Monday. On the forecast track, Idalia will remain near Bermuda today, and then begin to move away from the island tonight and Sunday. Little change in strength is forecast during the next few days. Idalia could transition to a subtropical storm later today. Swells generated by Idalia will affect the southeastern U.S. coast and Bermuda during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. Tropical Storm Gert is centered near 27.7N 54.3W at 02/0900 UTC or 610 nm ESE of Bermuda, moving NE at 2 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Numerous moderate to strong convection is noted south of the low center from 24N to 27N between 52W and 58W. Seas are peaking at 12 ft and extend 75 nm E of the center. Gert has moved little during the past several hours. A northward motion is expected to commence today and continue into Sunday. Little change in strength is forecast before Gert becomes absorbed by larger Post-tropical Idalia on Monday. Strong winds and moderate seas from Gert will move away from the Atlc offshore waters by tonight as Gert moves farther away. Newly upgraded Tropical Storm Katia is centered near 22.7N 29.4W at 02/0900 UTC or 500 nm NW of the Cabo Verde Islands, moving NNW at 11 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous moderate to scattered strong convection is noted from 22N to 27N between 26W and 31W. Katia is expected to turn to the northwest today and this general motion with a decrease in forward speed is expected through Monday. Weakening is expected to begin by early Sunday, and the system could degenerate into a remnant low by Sunday evening. Moderate to rough seas from Katia may impact the eastern Atlantic high seas Sun night into Mon. See hurricanes.gov for public advisories on the active systems and for the latest NHC Tropical Weather Outlook. See https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for the latest High Seas Forecast. ...TROPICAL WAVES... A strong tropical wave is along 18W from 18N southward, moving W at 10 to 15 kt. Numerous moderate to scattered strong convection is noted from 04N to 17N between 17W and 25W. Environmental conditions appear conducive for some gradual development of this system by the middle part of next week, and a tropical depression is likely to form while it moves westward to west-northwestward at 15 to 20 kt over the eastern and central portions of the tropical Atlantic. There is a low chance of tropical cyclone formation within the next 48 hours and high chance within the next 7 days. A central Caribbean Sea tropical wave is along 73W from 20N southward, moving W at 10 kt. Scattered moderate convection is noted near the northern tip of the wave across Haiti and eastern Jamaica. ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the Atlantic through the coast of Guinea near 10N14W to 14N23W, and then from 14N35W to 08N45W. See the Tropical Waves section for information on convection along the monsoon trough. ...GULF OF MEXICO... A surface trough extends across the Gulf from 30N86W to 22N96W. Scattered moderate to strong convection is noted from the north- central Gulf to the southern Bay of Campeche from 18N to 29N between 89W and 90W. Isolated thunderstorms are also noted along the Florida Panhandle. Winds are moderate or weaker across the Gulf. Seas are 4 ft or less across the basin. For the forecast, a weak surface trough with moderate winds over the central Gulf will drift westward through Sun as high pressure continues to build over the Gulf waters. Winds and seas could be higher near thunderstorms associated with the trough. Moderate to locally fresh winds will pulse at night off the NW Yucatan Peninsula through Tue night. Otherwise, gentle to moderate winds and slight seas will persist through Wed across the basin. ...CARIBBEAN SEA... Please read the TROPICAL WAVES section above for details on the convection affecting parts of the Caribbean Sea. Numerous strong convection is noted in the southwest Caribbean along the Eastern Pacific Monsoon Trough, S of 12N between 75W and 84W. Meanwhile, thunderstorms persist in the Cuba offshore waters and west of Jamaica. Scattered thunderstorms are also noted in the Gulf of Honduras. Fresh easterly trade winds cover the central Caribbean, except for strong within 120 nm of the coasts of NW Venezuela and NE Colombia. Seas in these waters are 6-9 ft. Mainly moderate easterly breezes and seas of 3-5 ft are evident in the eastern Caribbean and most of the NW Caribbean. For the forecast, fresh to strong trades in the central Caribbean will diminish today with the relaxing pressure gradient. Gentle to moderate winds with slight to moderate seas will prevail through the weekend. Fresh winds will return in the central and eastern Caribbean by early next week and continue through Wed. ...ATLANTIC OCEAN... Please read the SPECIAL FEATURES section for details about Post- Tropical Cyclone Idalia, Tropical Storm Gert and Tropical Storm Katia. A cold front extends from 30N63W to 24N73W to 28N81W, near the NE Florida coast. A pre-frontal trough is noted across the Bahamas from 23N72W to 24N79W. Scattered moderate to isolated strong convection is within 75 nm S of the trough. Moderate to strong NE winds are north of the front with gale force winds N of 29N. Meanwhile, in the central and eastern Atlantic, high pressure extends across the region. A trough extends from 30N38W to 20N47W. Scattered thunderstorms are noted along the trough from 24N to 29N between 38W and 42W. Gentle to moderate winds prevail outside of the systems described above with slight to moderate seas. For the forecast W of 55W, Post-Tropical Cyclone Idalia will move to 31.5N 63.9W this afternoon, 32.1N 62.2W Sun morning, become extratropical and move to 33.6N 60.2W Sun afternoon, and 35.7N 58.6W Mon morning. Gale force winds and rough to very rough seas associated with Idalia will impact the north waters through the weekend. Conditions will improve by Mon night. Meanwhile, Tropical Storm Gert will move to 28.0N 53.8W this afternoon, 29.2N 53.1W Sun morning, 30.8N 52.3W Sun afternoon, become post-tropical and move to 33.4N 51.7W Mon morning, and dissipate Mon afternoon. Gert will slowly move away from the eastern offshore waters today. Strong winds and moderate seas will begin to dissipate later today and improve by tonight. $$ AReinhart