000 AXNT20 KNHC 172359 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sat Sep 17 2022 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Tropical Storm Fiona is centered near 16.6N 64.9W at 17/0000 UTC or 70 nm S of St. Croix moving WNW at 7 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Peak wave heights are reaching 18 ft. Seas 12 ft or greater are within 120 nm of center, expect 90 nm SW quadrant. Numerous moderate to strong convection is noted within 270 nm SE semicircle. On the forecast track, the center of Fiona will move south of the U.S. Virgin Islands this evening, approach Puerto Rico tonight, and move across Puerto Rico by Sunday afternoon. Then, Fiona will be offshore of the Dominican Republic on Monday and near or to the east of the Turks and Caicos Islands on Tuesday. Strengthening is forecast, and Fiona is expected to become a hurricane before reaching the southern coast of Puerto Rico on Sunday. Additional strengthening is expected on Monday and Tuesday while Fiona moves over the southwestern Atlantic. NOAA buoy 42060 east-southeast of Fiona's center recently reported a sustained wind of 45 mph (72 km/h) and a gust to 51 mph (83 km/h). A station at Teagues Bay, St. Croix, recently reported a sustained wind of 36 mph (57 km/h) and a gust to 44 mph (70 km/h). Heavy rain associated with Fiona are likely to produce life-threatening flash flooding and urban flooding, along with mudslides in areas of higher terrain, particularly in portions of Puerto Rico and the eastern Dominican Republic. Very heavy rains and flooding have occurred over portions of the Leeward Islands since Friday. A station at St. Claude Matouba Irfa, in the mountains in southwestern Guadeloupe, recently measured a 24-hour rainfall total of 19.85 inches (504.2 mm). Swells generated by Fiona are affecting the Leeward Islands, the northern Windward Islands, the Virgin Islands, Puerto Rico, the northern coast of the Dominican Republic, the Turks and Caicos Islands, and the southeastern Bahamas. These conditions could 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 T.S. Fiona NHC Forecast/Advisory and NHC Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave is along 34W from 04N-16N, moving westward at 10-15 kt. Scattered showers are noted near the wave axis. A second tropical wave is along 47W from 07N-21N, moving westward about 10-15 kt. An area of disorganized showers and thunderstorms is near the northern end of the wave axis. Some slow development of this system is possible during the early or middle part of next week while it moves generally northward at about 10 kt. The latest Tropical Weather Outlook gives this system a low chance of tropical cyclone formation through five days. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic through the coast of Mauritania near 17N16W and continues to 12N25W. The ITCZ extends from 12N25W to 11N32W. Aside from convection related to the tropical waves described above, scattered moderate convection is noted from 08N-12N E of 17W to the coast of Africa. GULF OF MEXICO... High pressure over the SE CONUS extends a ridge across the Gulf waters. Since yesterday, convection has diminished across the basin, and currently isolated showers and thunderstorms are noted. However, showers and thunderstorms continue to flare up over Florida. A shortwave trough over the eastern Gulf is enhancing this convective activity. Gentle to moderate winds prevail across the Gulf region with seas generally in the 1-3 ft range. Winds and seas may be locally higher in and near thunderstorms. For the forecast, high pressure over the southeastern U.S. will maintain gentle to moderate easterly breezes and slight seas the next few days. CARIBBEAN SEA... Please see the Special Features section for information on Tropical Storm Fiona currently located over the northeastern Caribbean. Outside of Fiona, an area of low level convergence is enhancing convection from Haiti to near Cabo Gracias a Dios, Nicaragua, particularly from 15N-19N between 70W-85W. Another area of scattered moderate convection is noted N of the monsoon trough from 09N-12N between 73W-83W. Fresh to locally strong NE winds ahead of Fiona are noted per scatterometer data across the Mona Passage and just S of Dominican Republic. Elsewhere gentle to moderate winds prevail. Seas are generally 3-5 ft, except 5-7 ft in the Mona Passage and just S of Dominican Republic to near Cabo Beata. For the forecast, Fiona will move to 17.3N 65.5W Sun morning, strengthen to a hurricane near 18.1N 66.7W Sun afternoon, 19.0N 68.0W Mon morning, 20.1N 69.0W Mon afternoon, 21.4N 69.8W Tue morning, and 22.7N 70.5W Tue afternoon. Fiona will change little in intensity as it moves to 25.4N 70.7W Wed afternoon. ATLANTIC OCEAN... Please see the Special Features section for information on Tropical Storm Fiona, forecast to reach the Turks and Caicos Islands on Tuesday. Abundant moisture prevails across the western Atlantic supporting scattered to numerous showers and thunderstorms mainly N of 24N and W of 75W, including the NW Bahamas. A frontal boundary enters the forecast waters near 31N60W and continues SW to near 28N65W. A few showers are along the front. The remainder of the Atlantic is under the influence of a ridge, with a 1021 mb high pressure located near 33N53W. Under the influence of the ridge, mainly light and variable winds are noted roughly N of 25N. Winds increase between Fiona and the ridge to the N, with an area of moderate to fresh NE-E winds S of 22N between 64W-70W based on scatterometer data. An area of fresh to strong NE winds, with seas of 7-9 ft, is near the coast of Mauritania from 18N to 21N E of 20W. For the forecast west of 55W, Tropical Storm Fiona will move to 17.3N 65.5W Sun morning, strengthen to a hurricane near 18.1N 66.7W Sun afternoon, 19.0N 68.0W Mon morning, 20.1N 69.0W Mon afternoon, 21.4N 69.8W Tue morning, and 22.7N 70.5W Tue afternoon. Fiona will change little in intensity as it moves to 25.4N 70.7W Wed afternoon. Scattered showers and thunderstorms are expected over the far western part of the area through early next week as the trough lingers offshore the Florida coast. $$ GR