000 AXNT20 KNHC 182107 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Tue Sep 19 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 1800 UTC surface analysis and satellite imagery through 2000 UTC. ...SPECIAL FEATURES... Hurricane Nigel is centered near 28.0N 52.2W at 18/2100 UTC or 700 nm ESE of Bermuda, moving NW at 10 kt. Estimated minimum central pressure is 982 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Seas are peaking near 31 ft near and just north of the center. Numerous moderate to isolated strong convection is found near and up to 240 nm in the SW semicircle and 120 nm in the NE semicircle. Nigel is forecast to turn northward late Tuesday, and then accelerate northeastward through the rest of the week. Nigel is expected to strengthen during the next couple of days. A gradual weakening trend is forecast to begin by late Wednesday. 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... A tropical wave is off the Africa coast near 19W/20W from 18N southward, and moving west around 5 kt. Scattered moderate convection is found from 03N to 07N between 20W and 28W. A central Atlantic tropical wave is near 43W from 12N southward, and moving west at around 10 kt. Widely scattered moderate convection is noted from 04N to 12N between 32W and 43W. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic near the Gambia-Guinea Bissau border near 13N17W then extends west-southwestward across 10N21W to 07N44W. An ITCZ continues from 07N44W to 07N53W. Other than the convection described in the Tropical Waves section, scattered moderate isolated strong convection is evident from 05N to 07N between 47W and 54W. The eastern end of the East Pacific monsoon trough is producing numerous showers and scattered thunderstorms across the Caribbean waters north of Costa Rica, Panama and northwestern Colombia. ...GULF OF MEXICO... A modest cold front reaches west-southwestward from just north of Fort Myers, Florida to 25.5N86W, then turns west-northwestward as a dissipating stationary front to near Brownsville, Texas. Widely scattered showers and isolated thunderstorms are occurring from the NE Gulf to the SW Gulf. A surface trough at the western Bay of Campeche is causing scattered showers. Moderate NE winds are occurring N of the boundary with mainly gentle winds elsewhere. Seas are 2-4 ft N of the boundary and 1-2 ft elsewhere outside of any convection. For the forecast, the front will become stationary this evening and dissipate Tue. Winds will be moderate or weaker with slight seas through Thu, pulsing to moderate to fresh offshore the W 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 trough runs east-northeastward from a low near the Island of Youth across Jamaica and Hispaniola. These features are inducing isolated thunderstorms across the northwestern and north-central basin. Refer to the Monsoon Trough/ITCZ section for additional weather in the Caribbean Basin. A modest trade-wind pattern continues for much of the basin. Fresh ENE to ESE winds and 4 to 6 ft seas are present at the south- central basin. Light to gentle winds and seas of 1-3 ft are noted at the northwestern basin. Gentle monsoonal winds with seas at 3-4 ft exist offshore from Costa Rica and Panama. Gentle to moderate NE to SE winds prevail for the rest of the basin, except fresh to strong offshore N Colombia and NW Venezuela. Seas are 4-6 ft there and 3-5 ft across the remainder of the waters. For the forecast, long period north to northeast swell may impact the Caribbean passages and Tropical N Atlantic through the early part of this 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. A modest cold front runs southwestward from well off the Carolina coast across 31N75W to near Fort Pierce, Florida. A pre-frontal trough extends northeastward from near the NW Bahamas to the Straits of Florida. Widely scattered showers and isolated thunderstorms are found from N of 30N and within 150 nm E of the front. Mainly moderate winds are behind and just N of the front along with 4-6 ft seas. Refer to the Monsoon Trough/ITCZ and Tropical Waves sections at the beginning for additional convection in the Atlantic Basin. Outside the direct impact of Hurricane Nigel, a belt of fresh to strong trades is noted from 19N to 30N between the coast of Africa and 40W along with 8-11 ft seas. Moderate trades and 5-8 ft seas are found elsewhere N of 10N and E of 45W, with mainly gentle winds and 5-7 ft seas across the remainder of the tropical Atlantic waters. For the forecast W of 55W, Nigel will move to near 31N 54.5W Tue afternoon, 36N 53.5W Wed afternoon, then begin to slowly weaken as it moves to near 42N44W Thu afternoon. A cold front extending from 31N75W to Stuart, FL will reach from near 31N72W to near West Palm Beach, Florida Tue, then stall over the northern forecast waters through Thu. The boundary should begin moving N Fri as low pres develops along it, to the east of northern Florida. Winds and seas will likely increase in that area by the end of the week as a tight pressure gradient develops between the developing low pres off the Carolinas and high pressure inland over the U.S. $$ Lewitsky