| Post-Tropical Cyclone Marco Discussion Number 21 NWS National Hurricane Center Miami FL AL142020 400 AM CDT Tue Aug 25 2020 Marco has been devoid of any significant convection for at least 12 hours, and ASCAT scatterometer surface wind data around 0239Z suggested that Marco might have degenerated in a north-to-south elongated trough. Based on this information, Marco has been downgraded to post-tropical remnant low. Brisk southwesterly vertical wind shear of 30 kt is forecast to increase to near 35 kt in 24 hours, which should prevent the redevelopment of deep convection near the center. Marco's remnants are expected to move generally westward along or just south of the southern coast of Louisiana for the next 24 hours or until dissipation occurs. This is the last forecast/advisory issued by the National Hurricane Center on Marco. Additional information on this system can be found in high seas forecasts issued by the national weather service...under AWIPS header NFDHSFAT1 and WMO header FZNT01 KWBC. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 28.8N 91.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 12H 25/1800Z 28.8N 92.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 24H 26/0600Z...DISSIPATED $$ Forecaster Stewart Post-Tropical Cyclone Marco Advisory Number 21 NWS National Hurricane Center Miami FL AL142020 400 AM CDT Tue Aug 25 2020 ...MARCO BECOMES A REMNANT LOW JUST SOUTH OF LOUISIANA... ...THIS IS THE LAST ADVISORY... SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...28.8N 91.2W ABOUT 60 MI...100 KM S OF MORGAN CITY LOUISIANA ABOUT 110 MI...175 KM SSE OF LAFAYETTE LOUISIANA MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 400 AM CDT (0900 UTC), the center of Post-Tropical Cyclone Marco was located near latitude 28.8 North, longitude 91.2 West. The post-tropical cyclone is moving toward the west near 10 mph (17 km/h), and this general motion is expected to continue for the next day or so. On the forecast track, Marco should continue moving westward just offshore the coast of Louisiana until the system dissipates. Maximum sustained winds are near 30 mph (45 km/h) with higher gusts. Additional weakening is expected, and Post-Tropical Cyclone Marco is forecast to dissipate by early Wednesday, if not sooner. The estimated minimum central pressure is 1008 mb (29.77 inches). HAZARDS AFFECTING LAND ---------------------- SURF: Swells and rip currents affecting the north-central Gulf coast will gradually subside today. Please consult products from your local weather service office. NEXT ADVISORY ------------- This is the last public advisory issued by the National Hurricane Center on Marco. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php $$ Forecaster Stewart |