000 AXNT20 KNHC 222108 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sat Sep 23 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 2100 UTC. ...SPECIAL FEATURES... Tropical Storm Ophelia is centered near 32.9N 76.3W at 22/2100 UTC or 100 nm SE of Cape Fear North Carolina, moving NNW at 11 kt. Estimated minimum central pressure is 986 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Scattered moderate and isolated strong convection is noted within 150 nm in the W quadrant of Ophelia. Peak seas are currently around 23 ft SE of Cape Fear, North Carolina, per the Ocean Prediction Center based on nearby observations from NDBC buoys. On the forecast track, the center of Ophelia will approach the coast of North Carolina tonight, and then move across eastern North Carolina, southeastern Virginia, and the Delmarva Peninsula Saturday and Sunday. Little change in strength is forecast before landfall along the coast of North Carolina. Weakening is expected after landfall through the rest of the weekend. Swells generated by this system will affect much of the U.S. east coast through the weekend, likely causing life-threatening surf and rip currents. Heavy rainfall from this system could produce locally considerable flash, and urban flooding impacts across portions of the Mid- Atlantic states from North Carolina to New Jersey through Sunday. 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 Ophelia NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Invest 90L in the Central Tropical Atlantic: The axis of a tropical wave is analyzed along 35W with a 1009 mb low centered at 14N35W, or several hundred nautical miles west of the Cabo Verde Islands. Maximum winds are currently 25 kt and peak seas are up to 10-11 ft. Shower and thunderstorm activity associated with this area of low pressure has decreased slightly over the last few hours, however, further development is still expected. Scattered moderate convection is noted within about 420 nm in the NW semicircle of the low. A tropical depression is likely to form during the next couple of days while the system moves generally westward at 10 to 15 kt. The system is then expected to turn west-northwestward early next week as it moves over the central tropical Atlantic. The formation chance through 48 hours is high. Please see the latest Tropical Weather Outlook at www.hurricanes.gov for more information. ...TROPICAL WAVES... Please see the Special Features Section for details on the tropical wave (Invest 90L) along 35W. A tropical N Atlantic tropical wave has its axis along 58W, south of 22N, moving westward around 10 kt. Scattered moderate convection is noted from 08N to 15N between 56W and 64W, including over inland portions of NE South America. ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the Atlantic through the coast of Senegal near 14N17W and continues westward to the aforementioned low pressure near 14N35W, before terminating near 09N47W. No ITCZ is evident in the tropical Atlantic at this time. Scattered moderate convection is noted from 12N to 19N between 43W and 47W. GULF OF MEXICO... A weak surface trough is analyzed from 26N90W to 23N85W. Scattered showers and thunderstorms are noted between 60 nm and 180 nm NE of the trough. Moderate NE-E winds and 3-4 ft seas are NE of the trough. Otherwise, weak high pressure over the lower Mississippi Valley is supporting only light to gentle NE to E breezes and slight seas across the remainder of the basin this afternoon, along with 1-3 ft seas. For the forecast, weak high pressure over the lower Mississippi Valley extending across the northern Gulf will control the weather pattern across basin through early next week. This will support mostly gentle to moderate winds and slight seas, except for moderate winds pulsing to fresh winds offshore the western Yucatan Peninsula in the evenings. CARIBBEAN SEA... Weak surface ridging north of the Caribbean is forcing only gentle trades N of a line from the SW tip of Haiti to central Jamaica to the border of Nicaragua and Honduras, where seas are mainly 2-3 ft. Moderate to fresh trades prevail SE of there, highest in the central Caribbean with the pressure gradient is relatively tight, along with 3-6 ft seas, locally 7 ft near 11.5N76.5W. No deep convection is noted today over the Caribbean. For the forecast, moderate to fresh trade winds in the central Caribbean will change little through Sat. Winds across central portions will increase modestly Sun through Mon as high pressure strengthens across the region. Fresh to strong trade winds will pulse offshore of northern Colombia and northwest Venezuela during mainly the overnight and early morning hours into early next week. Looking ahead, seas will build in mixed NE and E swell across waters east of the Leeward Islands starting early Mon, ahead of low pressure moving westward across the tropical Atlantic, possibly as the next tropical cyclone. ATLANTIC OCEAN... Please see the Special Features section section above for information on Tropical Storm Ophelia and Invest 90L. A mid-level trough extends from 31N73W to near Key Largo, Florida. Scattered showers and thunderstorms are noted within 120 nm SE of this feature, with similar activity from 22N to 27N between 67W and 72W. A weak surface trough is analyzed from 31N28.5W to 29.5N35W to 30N40W with a parent front just N of 31N. Elsewhere, ridging extends across the Atlantic along roughly 30N/31N. Between the ridge and the monsoon trough/ITCZ, the trades are gentle to moderate with seas 5-8 ft. Winds and seas are higher in the vicinity of Ophelia extending S into our area to 29N, and also near Invest 90L. Isolated to widely scattered moderate convection is noted from 19N to 28N between 45W and 59W in association with an upper-level trough. For the forecast west of 55W, Ophelia will move further northward and inland across coastal North Carolina on Sat. Large northerly swell will move through the waters W of 70W tonight through early Sun before fading. A weak ridge will build in the wake of Ophelia off Florida through early next week, although a trough will persist across the Bahamas through Mon. Looking ahead, seas will build in mixed NE and E swell across waters northeast of the Leeward Islands starting Mon, ahead of low pressure moving westward across the tropical Atlantic, possibly as the next tropical cyclone. $$ Lewitsky