ZCZC MIATCPAT4 ALL TTAA00 KNHC DDHHMM BULLETIN Tropical Storm Marco Intermediate Advisory Number 15A NWS National Hurricane Center Miami FL AL142020 100 AM CDT Mon Aug 24 2020 ...A WEAKER MARCO CONTINUES MOVING TO THE NORTH-NORTHWEST... SUMMARY OF 100 AM CDT...0600 UTC...INFORMATION ---------------------------------------------- LOCATION...27.2N 87.9W ABOUT 150 MI...240 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H PRESENT MOVEMENT...NNW OR 340 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for.... * Morgan City Louisiana to Ocean Springs Mississippi * Lake Borgne A Hurricane Warning is in effect for... * Morgan City Louisiana to the Mouth of the Pearl River A Storm Surge Watch is in effect for... * Sabine Pass to Morgan City Louisiana * Ocean Springs Mississippi to the Mississippi/Alabama border * Lake Pontchartrain and Lake Maurepas A Hurricane Watch is in effect for... * Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans A Tropical Storm Warning is in effect for... * Mouth of the Pearl River to the Mississippi/Alabama border * Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans * Cameron to west of Morgan City A Tropical Storm Watch is in effect for... * Mississippi/Alabama border to the Alabama/Florida border A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Hurricane Watch means that hurricane conditions are possible within the watch area. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 100 AM CDT (0600 UTC), the center of Tropical Storm Marco was located by an Air Force Reserve Hurricane Hunter plane near latitude 27.2 North, longitude 87.9 West. Marco is moving toward the north-northwest near 12 mph (19 km/h). A turn toward the northwest is expected later this morning. Marco is forecast to approach the coast of Louisiana this afternoon, and then turn westward and move near or over the coast through Tuesday. Data from the Hurricane Hunter plane indicate that maximum sustained winds have decreased to near 65 mph (100 km/h) with higher gusts. Fluctuations in intensity are possible during the next 24 hours, but Marco is forecast to weaken rapidly by early Tuesday. Tropical-storm-force winds extend outward up to 70 miles (110 km) from the center. The estimated minimum central pressure based on data from the reconnaissance aircraft is 1002 mb (29.59 inches). HAZARDS AFFECTING LAND ---------------------- STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Morgan City LA to Mouth of the Mississippi River...4-6 ft Mouth of the Mississippi River to Ocean Springs MS including Lake Borgne...3-5 ft Lake Pontchartrain and Lake Maurepas...2-4 ft Intracoastal City LA to Morgan City LA...2-4 ft Sabine Pass to Intracoastal City...1-3 ft Ocean Springs MS to the AL/FL Border including Mobile Bay...1-3 ft The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. WIND: Hurricane conditions, primarily in gusts, are still possible within the hurricane warning area by midday, with tropical storm conditions likely by midday. Tropical storm conditions are possible within the tropical storm watch area by the afternoon, and hurricane conditions are possible within the hurricane watch areas late today. RAINFALL: Marco is expected to produce total rainfall accumulations of 3 to 5 inches with isolated maximum amounts of 10 inches across portions of the northeast and north-central Gulf coast through Tuesday. This rainfall may result in areas of flash, urban and small stream flooding along the area. SURF: Swells generated by Marco are likely to affect portions of the northern Gulf Coast for the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. TORNADOES: Isolated tornadoes are possible across southeast Louisiana, southern Mississippi, southern Alabama, and the Florida Panhandle today and tonight. NEXT ADVISORY ------------- Next complete advisory at 400 AM CDT. $$ Forecaster Blake NNNN