000 AXNT20 KNHC 171141 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 1130 UTC. ...SPECIAL FEATURES... Tropical Storm Fiona is over the northeastern Caribbean Sea near near 16.4N 63.3W at 17/0900 UTC or 110 nm W of Guadeloupe moving W at 11 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Peak wave heights of 21 ft are near and northeast of the center. Seas 12 ft or greater extend as far as 240 nm from the center of Fiona in the NE quadrant. Shear has decreased and the center is now tucked into the convection. A large, almost symmetrical, area of numerous moderate to scattered strong convection is observed on latest satellite imagery from 13N to 20N and between 58W and 65W. A westward to west-northwestward motion with a decrease in forward speed is expected through Sun night. A turn toward the northwest is forecast early next week. On the forecast track, the center of Fiona is expected to move near or just south of the Virgin Islands and Puerto Rico today through Sun, and approach the southern or eastern coast of the Dominican Republic Sun night and Mon. Fiona is forecast to move across the Dominican Republic Sunday night and Monday. Gradual strengthening is forecast, and Fiona could be near hurricane strength when it moves near moves near Puerto Rico and the Dominican Republic this weekend. 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... An eastern Atlantic tropical wave has its axis extending from 16N32W to 11N33W to 04N32W. It is moving westward at 15-20 kt. Clusters of scattered moderate convection are evident from 09N to 13N between the wave axis and 36W. The southern part of this convective activity appears to be weakening. A central Atlantic tropical wave has its axis along 45W from 08N to 25N, moving westward about 15 kt. An area of disorganized scattered moderate is north and northeast of the northern part of the wave from 19N to 26N between 40W-45W. Scattered showers and thunderstorms are along the wave axis within 60 nm of 18N45W. Overnight ASCAT data revealed fresh to strong easterly winds from 17N to 23N between 40W-47W. Wave heights with these winds are in the 5-7 ft range. Some slow development of this system is possible during the early or middle part of next week while it moves slowly northwestward to northward. 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 The Gambia near 13.5N16W and continues to 109N23W to 10N31W and to 08N39W. Aside from convection related to the tropical wave along 45W, scattered moderate to isolated strong convection is seen within 180 nm south of the trough between 16W-24W. GULF OF MEXICO... A surface trough extends from near Destin, Florida to 28N89W and to 25N90W, while an upper-level trough is moving through the eastern Gulf. These features are acting upon very deep tropical moisture that is present over the area, resulting in scattered and thunderstorms over some areas of the eastern Gulf. A surface trough is analyzed over the western Bay of Campeche. Scattered to numerous showers and thunderstorms are noted over the Bay of Campeche south of 21N between 93W-96W. Isolated showers and thunderstorms are elsewhere over the Gulf south of 26N. Weak high pressure over the area supports gentle to moderate easterly winds. Wave heights of 3-4 ft are over he northern Gulf, especially N of 27N. Lower wave heights of 1-3 ft are noted elsewhere in the basin. For the forecast, high pressure over the southeastern U.S. is maintaining gentle to moderate easterly breezes and slight seas. This will continue through the next few days. Abundant deep tropical moisture in place over the eastern Gulf along with an upper trough over the eastern Gulf. This should continue to support scattered showers and thunderstorms over the eastern Gulf through the rest of the weekend. CARIBBEAN SEA... Please see the SPECIAL FEATURES section for information on Tropical Storm Fiona currently over the northeastern Caribbean. Outside of Fiona, a weak surface trough along 73W from 15N to 20N is underneath an upper-level trough. Divergence east of the upper-level trough is supporting scattered showers and a few thunderstorms over the north-central Caribbean Sea from 15N to 18N between 70W-76W. Scattered showers and thunderstorms are noted from 13N to 16N west of 77W to the along the coasts of Honduras and Nicaragua. Similar activity is over the southwestern Caribbean, where the eastern extension of the eastern Pacific monsoon trough is analyzed. Isolated showers are elsewhere north of 16N and west of 82W. Moderate to fresh trade winds are occurring in the north-central Caribbean, Windward Passage and Gulf of Honduras per overnight ASCAT data passes. Wave heights with these winds are in the 4-6 ft range. Gentle to moderate trade winds along with lower wave heights of 2-4 ft are elsewhere. For the forecast, Tropical Storm Fiona near 16.4N 63.3W 1000 mb, or about 110 nm west of Guadeloupe at 5 AM EDT and moving W at 11 kt, with maximum sustained winds 50 kt gusts 60 kt will move to near 16.8N 64.8W this afternoon, to near 17.1N 66.3W late tonight with maximum sustained winds 60 kt gusts 75 kt, to near 17.7N 67.7W Sun afternoon, then strengthen to a hurricane as it approaches the northeast coast of the Dominican Republic late Sun night with maximum sustained winds 65 kt gusts 80 kt. Fiona is forecast to maintain intensity as it reaches near 19.7N 69.9W Mon afternoon, to near 20.8N 70.6W late Mon night, and continue to strengthen as it moves northward over the Atlantic and farther from the Caribbean Sea. Residual swell from Fiona will linger over the northeastern Caribbean. ATLANTIC OCEAN... Please see the SPECIAL FEATURES section for information on Tropical Storm Fiona. A surface trough is analyzed from near 29N76W to the eastern part of the Straits of Florida. Scattered showers and thunderstorms moving eastward are to the northwest of the trough, reaching to north of the area between 75W-80W. Isolated showers are elsewhere near the trough. Moderate to fresh west- northwest winds behind a frontal boundary are north of about 30N and between 65W-69W. Wave heights are in the range of 3-6 ft over the waters west of 67W. Farther south, moderate to fresh trade winds are south of 21N and between 71W-77W, with related wave heights of 4-7 ft. The remainder of the basin is dominated by a large ridge over the central Atlantic maintaining fairly tranquil weather conditions. In the eastern Atlantic, overnight partial ASCAT data depicts fresh to strong north to northeast winds from 17N to 23N and east of 30W, with the strongest winds occurring off northern Mauritania. Similar winds are evident off Morocco and Western Sahara and the waters surrounding the Canary Islands. Wave heights are 6-9 ft north of 16N and east of 25W. Elsewhere, moderate or lighter winds winds are present along with wave heights of 4-6 ft. For the forecast west of 55W, Tropical Storm Fiona over the northeastern Caribbean Sea near 16.4N 63.3W 1000 mb at 5 AM EDT moving W at 11 kt, with maximum sustained winds 50 kt gusts 60 kt is forecast to move near or just south of Puerto Rico through Sun, and strengthen to a hurricane as it nears the northeast coast of the Dominican Republic late Sun night with maximum sustained winds 65 kt gusts 80 kt. It is forecast to maintain intensity as it reaches near 19.7N 69.9W Mon afternoon, to near 20.8N 70.6W late Mon night, and strengthen as it reaches near 23.0N 71.5W late Tue night with maximum sustained winds 75 kt gusts 90 kt and to near 26.0N 71.5W late Wed night with maximum sustained winds 80 kt gusts 90 kt. Scattered showers and thunderstorms are expected over the far western part of the area through early next week as a trough lingers offshore the Florida coast. $$ Aguirre