000 AXNT20 KNHC 181054 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Mon Sep 18 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 1045 UTC. ...SPECIAL FEATURES... Recently upgraded Hurricane Nigel is centered near 26.5N 50.7W at 18/0900 UTC or about 810 nm ESE of Bermuda, moving NW at 10 kt. Estimated minimum central pressure is 984 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Satellite imagery shows a wide convective banding feature consisting numerous moderate to strong convection that extends from 27N to 29N between 47W-51W and from 15N to 26N between 51W-53W. The band coils around a CDO (Central Dense Overcast) type feature that consists of similar convection from 24N to 26.5N and between 49W-52W. Scattered moderate to isolated strong convection is from 26N to 27N between 47W-49W. Nigel is intensifying, and it is forecast to maintain its present motion over the next couple of days, then is forecast to turn northward late Tue, and accelerate northeastward through the rest of the week. Peak seas to 26 ft extend outward from the center for up to 210 nm in the NE quadrant. Rapid strengthening is forecast during the next 48 hours. Nigel will likely become a hurricane overnight, and is forecast to become a major hurricane on Tue. 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 Nigel NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... An central Atlantic tropical wave has its axis along 42W from 02N to 12N, moving westward 10-15 kt. Scattered moderate convection is within 60 nm west of the wave from 07N to 11N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through the coastal border of Senegal and Guinea-Bissau to 09N23W to 07N30W to 05N39W. The ITCZ extends from 05N43W to 05N50W. Scattered moderate to isolated strong is south of the trough from 06N to 09N between the coast of Africa and 20W, within 120 nm south of the trough between 30W-33W and within 30 nm north of the trough between 32W-34W. Scattered moderate convection is north of the trough from 10N to 12N between 28-39W. ...GULF OF MEXICO... A surface trough extends from the east-central Florida southwest to near Naples, Florida. Otherwise, relatively week high pressure is over the area. The associated gradient supports generally light to gentle northeast to east winds over the area, except for moderate north winds north of 28N and east of 89W. These winds are behind a frontal trough that is moving across the NE Gulf. Scattered showers and a few thunderstorms are over eastern Bay of Campeche. Isolated showers and thunderstorms are noted from 22N to 27N between 90W-97W and from 25N to 29N between 83W-90W. Wave heights are 1-2 ft over the area. For the forecast, a weak trough just inland the Texas coast will be replaced by another weak trough on Mon that will move off the Texas coast and over NW Gulf. The trough is expected to be accompanied by a wind shift along with a few showers and thunderstorms. Winds will be moderate or weaker with slight seas through Thu, pulsing to moderate to fresh offshore the western Yucatan in the evenings. Winds may freshen in the NE Gulf by the end of the week due to building high pressure north of the area with seas also building. ...CARIBBEAN SEA... An upper-level northeast to southeast oriented trough extends from NW Cuba toward the NE Caribbean Sea. Isolated showers and thunderstorms are noted north of 16N and west of 70W. The monsoon trough is along 09N/10N from 73W in Colombia, beyond Costa Rica. Scattered to numerous moderate to strong convection is confined to the southwestern Caribbean south of 12N between 76W-81W. Moderate and fresh northeast to east winds are between 63W and the Windward Passage, and reaching the coast of Central America, during the last 24 hours. Gentle to moderate northeast to east winds are west of 75W to the coast of Central America. Wave heights are 2 ft on the Atlantic side of the eastern Caribbean Sea islands, from 3-4 ft east of 80W, except for 4-5 ft to the north of Panama, 2 ft off the coast of southeastern Nicaragua and 1 ft over the rest of the Sea. For the forecast, long period north to northeast swell may impact the Caribbean passages and Tropical N Atlantic through the early part of the week. Moderate to fresh trades will prevail in the central Caribbean, locally strong at times offshore northern Colombia, with moderate or weaker winds elsewhere through the week. ...ATLANTIC OCEAN... Please read the Special Features Section for details about Hurricane Nigel. Fresh to strong NE winds are from 20N northward from 30W eastward. Mostly moderate to some fresh northeast winds are elsewhere north of 10N and east of 40W. Moderate to fresh southeast to south winds are north of 24N and east of 69W. Moderate southerly winds are south of the monsoon trough/ITCZ and east of 50W. The wave heights range from 7-9 ft north of 20N and west of 60W, and north of 22N east of 35W as noted in altimeter data passes. Higher wave heights of 10-12 ft are near the coast of Africa, where a tight pressure exists between strong high pressure and lower pressure in western Africa. Wave heights of 4-7 ft are over the rest of the Atlantic. Isolated showers and thunderstorms are seen from 10N to 20N between 40W-47W, and from 20N to 22N between 27W-32W. For the forecast W of 55W, Hurricane Nigel is near 26.5N 50.7W at 5 AM EDT, and is moving northwest at 10 kt. Maximum sustained winds are 70 kt with gusts to 85 kt, and the minimum central pressure is 984 mb. Nigel will continue strengthen as it moves to near 27.6N 51.8W this afternoon with maximum sustained winds 85 kt gusts 105 kt, to near 29.1N 53.3W late tonight with maximum sustained winds 100 kt gusts 120 kt, to near 30.8N 54.6W Tue afternoon and maintain intensity as it moves to north of the area near 33.1N 55.0W late Tue night. Nigel is forecast to gradually weaken as it accelerates northeastward farther away from the area through the rest of the week. A cold front along the southeastern United Stated coast will reach from near 31N72W to near Jupiter, Florida Tue morning, then stall over the northern forecast waters through the end of the week. Winds and seas may increase west of the stalled boundary by the end of the week as a tight pressure gradient develops due to building high pressure inland and a developing coastal trough off the Carolinas. $$ Aguirre