000 AXNT20 KNHC 201201 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Hurricane Fiona is centered near 21.6N 71.2W at 20/1200 UTC or 10 nm NW of Grand Turk Island moving NNW at 9 kt. Estimated minimum central pressure is 960 mb. Maximum sustained wind speed is 100 kt with gusts to 120 kt. Fiona is the first major hurricane of the 2022 Atlantic hurricane season. Maximum wave heights are currently 29 ft, but are forecast to build quite significantly to around 45 ft over the next 48 hours as Fiona moves to a position near 27N71W by 22/0600 UTC. Satellite imagery depicts a small eye feature with Fiona. Numerous moderate to strong convection is noted within 210 nm of the center in the NE quadrant, 120 nm in the SE quadrant, 60 nm in the SW quadrant and within 90 nm of the center in the NW quadrant. Outer bands consisting of scattered moderate to isolated strong convection are seen 17N to 23N between 65W-69W and from 24N to 26N between 67W-71W. Scattered moderate convection is within 60 nm of 24N73W. Fiona is forecast to continue on its present motion through today, followed by a turn toward the north tonight or Wed. On the forecast track, the center of Fiona will pass near Grand Turk and the other eastern Turks and Caicos during the next few hours. Strengthening is expected during the next couple of days. On the forecast track, the center of Fiona will pass near Grand Turk and the other eastern Turks and Caicos during the next few hours. 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 continue to spread westward across the southwestern Atlantic toward the central and northwestern Bahamas and the east coast of the United States through Wed night. The swells 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 NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Scattered moderate to isolated strong convection continues to increase in association with a 1014 mb low pressure system located over the central subtropical Atlantic near 31N46W. This convection is observed within 180 nm north of the low between 44W-48W. Scattered showers and isolated thunderstorms are seen from 29N to 31N between 43W-47W. Overnight ASCAT data depicted fresh to strong winds associated with this low pressure, mainly within 120 nm in the E semicircle of the low. Environmental conditions appear marginally favorable for additional development, and a tropical depression is likely to form over the next couple of days before upper-level winds become less conducive later this week. The system should generally move toward north or northeast. This system has a medium chance of tropical cyclone development within the next 48 hours. ...TROPICAL WAVES... A central Atlantic tropical wave has its axis along 51W from 04N to 15N, moving westward at 15 kt. Satellite imagery shows increasing clusters of numerous moderate to strong convection ahead of the wave from 08N to 11N between the wave and 59W. An overnight ASCAT data pass revealed fresh to strong southeast to south winds 180 nm east of the wave from 07N to 11N. Gradual development of this system is forecast during the next several days as the system approaches the Windward Islands, and a tropical depression could form toward the latter part of this week or weekend as the system moves into the eastern and central Caribbean sea. The chance of tropical cyclone formation during the next 48 hours is low, but medium within the next 5 days. Another central Atlantic tropical wave has its axis along 60W from 08N to 20N. It is moving westward about 15 kt. A surface trough extends north-northeast of the wave from 20N60W to 26N56W. Isolated showers and thunderstorms are along and within 60-90 nm either side of the wave south of 15N. These showers and thunderstorms will affect the Windward Islands this morning during the next several hours. Scattered showers and isolated thunderstorms are east of the trough from 22N-29N between 49-56W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal Senegal near 14N17W and continues southwestward to low pressure of 1010 mb near 09N29W and to 09N36W, where the ITCZ begins and continues to 10N44W and to 11N50W. It resumes west of a tropical wave from 10N52W to 11N59W. Scattered moderate to isolated strong convection is within 240 nm northwest of the 1010 mb low. Scattered moderate convection is within 120 nm south of the trough between the coast of Africa and 18N. 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 and altimeter data passes indicate wave heights of 2-4 ft across the Gulf, highest in the central Gulf. 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. Scattered showers and thunderstorms trailing behind from Fiona are north of 16N between 64W-71W. Similar activity is south of 15N and west of 74W and south of 14N between 64W-67W. Isolated showers and thunderstorms are elsewhere across the basin. Fresh northeast winds are in the Windward Passage and in between Jamaica and Haiti per latest ASCAT data. Wave heights with these winds 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. Wave heights are still 8 ft or higher in the Mona passage, but will be subsiding later today. In the northwestern Caribbean, gentle to moderate northeast to east winds continue, where seas are 1-2 ft. Major Hurricane Fiona north of the area located about 20 nm southeast of Grand Turk Island will continue to move farther away from the Caribbean through Wed while strengthening. Residual swell over the eastern Caribbean from Fiona will subside through Tue. A tropical wave, currently east of the area near 52W, is expected to move across the Tropical N Atlantic from tonight through Wed, across the eastern Caribbean Wed night through Thu and across the central Caribbean Fri through Sat night. Gradual development of this system is forecast during the next several days as the system approaches the Windward Islands, and a tropical depression could form toward the latter part of this week or weekend as the system moves into the eastern and central Caribbean sea. ATLANTIC OCEAN... Refer to the Special Features section above for details on Hurricane Fiona and the 1014 mb low pressure system near 31N46W. Refer to the Tropical Waves section for details on the tropical waves moving across the basin. A surface trough extends from near 31N78W southwestward across the central Florida Peninsula. Scattered showers and thunderstorms remain 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. Wave heights are 5-6 ft in this area. Elsewhere outside of the circulation of Fiona, winds are moderate or weaker with wave heights of about 4-6 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, major Hurricane Fiona is near 21.3N 70.9W 967 mb at 5 AM EDT moving NNW at 9 kt. Maximum sustained winds 100 kt gusts 120 kt. Fiona will continue to strengthen as it moves to near 22.3N 71.4W this afternoon, to near 23.6N 71.7W late tonight with maximum sustained winds 115 kt gusts 140 kt, to near 25.1N 71.5W Wed afternoon with maximum sustained winds 120 kt gusts 145 kt, and maintain intensity as it moves to near 27.1N 70.7W late Wed night and to near 29.6N 69.4W Thu afternoon. Fiona will begin to weaken as it tracks northeastward to north of the area near 32.6N 66.8W late Thu night, and transition to a post- tropical cyclone well north of the area by late 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. $$ Aguirre