000 AXNT20 KNHC 200434 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Tue Sep 20 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 0000 UTC surface analysis and satellite imagery through 0420 UTC. ...SPECIAL FEATURES... Hurricane Fiona is centered near 20.6N 70.3W at 20/0300 UTC or 70 nm SE of Grand Turk Island moving NNW at 9 kt. Estimated minimum central pressure is 971 mb. Maximum sustained wind speed is 95 kt with gusts to 115 kt. Maximum seas with this system can reach 26 ft at this time, but are forecast to build to 46 ft over the next 48 hours as Fiona moves to a position near 26N71W by 22/0000 UTC. Scattered to numerous moderate to strong convection is noted within 210 nm of the center in the E semicircle, 180 nm SW quadrant and 75 nm NW quadrant. Scattered moderate convection is elsewhere within 300 nm NE quadrant, 360 nm SE quadrant and 150 nm NW quadrant, including over Puerto Rico, the Virgin Islands, the Dominican Republic and the Turks and Caicos Islands. Satellite imagery shows a small eye of about 10 nm in diameter. Strengthening is expected during the next couple of days, and Fiona is forecast to become a major hurricane later today. On the forecast track, the center of Fiona will pass near easternmost Turks and Caicos early today. Swells generated by Fiona are affecting the Virgin Islands, Puerto Rico, the northern coast of Hispaniola, the Turks and Caicos Islands, and the southeastern Bahamas. These swells will spread W across the SW Atlantic toward the central and northwestern Bahamas and the east coast of the United States through midweek. The swells could cause life- threatening surf and rip current conditions. 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 NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Shower and thunderstorm activity has increased in association with a 1014 mb low pressure located over the central subtropical Atlantic near 30N46W. Scattered moderate convection is noted north of 29N between 46W-47W. Recent ASCAT satellite wind data show fresh winds associated with this low pressure. Some slow development is possible during the next couple of days, and a tropical depression could form during that time before environmental conditions become less conducive later this week. The system should generally move toward the N or NE. The system has a medium chance of tropical cyclone development within the next 48 hours. ...TROPICAL WAVES... An Atlantic Ocean tropical wave extends its axis along 49/50W from 15N southward, moving W at 15 kt. Scattered moderate and isolated strong convection is seen within 120 nm either side of the wave axis from 07N to 13N. An Atlantic Ocean tropical wave extends its axis along 59W from 20N southward to Guyana, moving W at 10-15 kt. A surface trough extends N of the wave from 20N58W to 26N55W. Scattered moderate convection is noted within 90 nm east and within 60 nm west of the wave axis from 11N to 14.5N. These showers and thunderstorms will affect the Windward Islands this morning during the next several hours. Isolated showers and tstorms are along and E of the surface trough, from 22N-28N between 50W-58W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal Senegal near 14N17W to 10N24W to 08N36W. The ITCZ continues from 08N36W to 11N48W, then resumes W of a tropical wave from 10N51W to 11N57W. Scattered moderate convection is noted from 06N to 12N between 28W and 38W, and from 07N-13N between 52W-57.5W. GULF OF MEXICO... High pressure over the southeastern United States extends weak surface ridging southwestward into the north-central and NW Gulf of Mexico, supporting moderate NE to E winds across the eastern and central Gulf. A surface trough is over the far eastern Gulf, off southwest Florida. Recent buoy observations indicate seas are 2-4 ft across the Gulf, highest in the central Gulf. Seas could be as high as 5 ft there. 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 above for information on Hurricane Fiona. Outside of convection associated with Fiona, scattered showers and thunderstorms are within 60 nm of the coast of Honduras. Scattered showers and tstorms are noted within 120 nm off the coast of Venezuela. Fresh N to NE winds are occurring in the Windward Passage, and in between Jamaica and Haiti currently, where seas are 4-5 ft. Moderate SE winds are occurring east of 70W, while moderate W winds are noted on the latest scatterometer data between 70W-78W. Seas are still 5-7 ft over the east Caribbean in large swell coming through the Mona Passage. Seas are still 8 ft or higher in the Mona passage, but will be subsiding later today. In the NW Caribbean, gentle to moderate NE to E winds prevail, where seas are 1-2 ft. Hurricane Fiona is north of the basin, located about 70 nm SE of Grand Turk Island, and will continue to move farther away from the Caribbean through Wed while strengthening. Residual swell over the eastern Caribbean from Fiona will subside through today. A tropical wave, currently east of the area near 50W, is expected to move across the Tropical N Atlantic tonight through Wed, across the eastern Caribbean Wed night through Fri night and across the central Caribbean Sat and Sat night. ATLANTIC OCEAN... Refer to the Special Features section above for details on Hurricane Fiona and the 1014 mb low near 30N46W. Refer to the Tropical Waves section for details on the tropical waves moving across the basin. A surface trough extends from 31N79W southwestward across the Florida Peninsula. Scattered showers and tstorms prevail across the western Atlantic waters mainly north of 28N and west of 76W. Fresh trade winds are noted in the tropical Atlantic from 11N-18N between 40W-56W. Seas are 5-6 ft in this area. Elsewhere outside of the circulation of Fiona, winds are moderate or weaker with seas 3-6 ft. The area of 20 kt or greater winds associated with the circulation of Fiona currently extend from the Greater Antilles to 25N between 65W-73W. Seas of 8 ft or greater extend from 18N-26N between 65W-73W For the forecast west of 55W, Hurricane Fiona will strengthen to a major hurricane later this morning near 22N71W, move to near 25N71W Wed morning, to near 28.5N70W Thu morning, and to near 31N68W Thu evening. Fiona will move well north of the forecast waters through Sat, transitioning to a post-tropical cyclone Sat night. Swells generated by Fiona will spread westward across the southwestern Atlantic toward the central and northwestern Bahamas through Wed night. A cold front will drop south over the northern and central waters Fri through Sat night followed by fresh northeast winds and building seas. High pressure will build in behind the cold front. $$ Hagen