000 AXNT20 KNHC 211759 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Thu Sep 21 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 1200 UTC surface analysis and satellite imagery through 1730 UTC. ...SPECIAL FEATURES... Hurricane Nigel is centered near 42.2N 45.0W at 21/1500 UTC or 440 nm SE of Cape Race Newfoundland, moving NE at 26 kt. Estimated minimum central pressure is 977 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. Peak seas are currently 43 ft. Scattered moderate convection is within 270 nm of the center of Nigel. This general motion to the NE is expected to continue for the next day or two. Weakening is forecast during the next couple of days, and Nigel is forecast to become a post-tropical cyclone tonight or early Friday. Hazards associated with Nigel will remain well north of the TAFB forecast waters. Please read the latest HIGH SEAS FORECAST issued by the Ocean Prediction Center at website under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php. Please see the latest Nigel NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Potential Tropical Cyclone Sixteen is centered near 28.7N 75.9W at 21/1500 UTC or 320 nm SE of Charleston South Carolina, moving N at 8 kt. Estimated minimum central pressure is 1012 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Scattered moderate isolated strong convection is from 25N to 31N between 72W and 75W. This general motion to the north is expected to continue through early Friday. A north-northwestward to northward motion is forecast by late Friday and continue into the weekend. On the forecast track, the center of the cyclone is expected to approach the coast of North Carolina within the warning area Friday night and early Saturday. Strengthening is expected during the next day or two, and the system is forecast to become a tropical storm as it approaches the coast of North Carolina. Regardless of whether the system become a tropical storm, the system is expected to bring tropical-storm conditions to portions of the southeast and mid-Atlantic coast. 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 Sixteen NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Eastern Tropical Atlantic: A far eastern Atlantic tropical wave has its axis along 26W from 05N to 22N. It is moving westward at 10-15 kt. Scattered moderate convection is from 12N to 17N between 26W and 31W. Seas are 8-9 ft near the tropical wave. Environmental conditions are forecast to be conducive for gradual development of this system, and a tropical depression is likely to form this weekend or early next week while the system moves generally westward at 10 to 15 kt across the eastern and central tropical Atlantic. There is a MEDIUM chance of development through 48 hours. Please see the latest Tropical Weather Outlook at www.hurricanes.gov for more information. ...TROPICAL WAVES... A weak central Atlantic tropical wave has its axis along 38W from 04N to 13N. It is moving westward at around 5-10 kt. No significant convection is noted at this time. The tropical wave may dissipate or be absorbed by the tropical wave currently along 26W. A western Atlantic tropical wave has its axis along 55W, from 04N to 23N, moving westward at 10-15 kt. No significant convection is occurring with this tropical wave. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean near 18N16W and continues to 1011 mb low pressure centered near 14N27W to 09N32W to 10N53W. Scattered showers are within 180 nm of the monsoon trough. GULF OF MEXICO... Ridging prevails across the basin, as high pressure centered over the Northeast US presses south-westward. The remnants of a frontal boundary is decaying across the Florida Keys and far SE Gulf. Scattered moderate convection is noted across the eastern Gulf waters, winds and seas may be locally higher in and near the convection. Light to gentle winds and 1-3 ft seas are noted across the basin. For the forecast, high pressure will be in control of the weather pattern across the Gulf waters allowing for generally gentle to moderate east to southeast winds and slight seas, except pulsing to moderate to fresh offshore the western Yucatan Peninsula in the evenings. Developing low pressure east of Florida will tighten the pressure gradient over the NE Gulf bringing moderate to locally fresh NE winds across the NE Gulf tonight into Fri. A frontal trough associated with the aforementioned low pressure will move across the southeastern Gulf and the Straits of Florida tonight into Fri. CARIBBEAN SEA... The latest scatterometer data shows fresh winds in the south- central Caribbean. Elsewhere, trades are gentle to moderate across most of the basin with seas of 4-6 ft. However, in the NW Caribbean, winds are light and variable and seas are 2-4 ft. Scattered showers are noted across the Lesser Antilles. For the forecast, long period north to northeast swell moving through the Tropical N Atlantic waters and Caribbean passages will subside today. Moderate to fresh trade winds in the central Caribbean will change little through the next few days. Northeast to east trade winds will pulse to fresh to strong speeds offshore northern Colombia and northwest Venezuela during the afternoons and at night into early next week. ATLANTIC OCEAN... Please see the SPECIAL FEATURES section and the TROPICAL WAVES section above. A decaying stationary front extends from POTENTIAL T.C. SIXTEEN across the Bahamas to the Florida Keys. A stationary front extends from POTENTIAL T.C. SIXTEEN north-eastward to 31N73W. Convection described in SPECIAL FEATURES. Elsewhere across the tropical Atlantic, 1022 mb high pressure centered near 29N31W guides the sensible weather. This morning's scatterometer data depicts gentle to moderate trades across the basin, locally fresh along 20N where the pressure gradient is maximized. Seas are 4-7 ft in open waters. For the forecast W of 55W, PTC Sixteen will move to 30.0N 75.5W this evening,and will be N of area near 31.7N 75.4W by Fri morning. In its wake, high pressure ridging will build from E to W just north of the forecast waters into early next week. $$ Mahoney