BULLETIN Hurricane Ida Advisory Number 15 NWS National Hurricane Center Miami FL AL092021 400 PM CDT Sun Aug 29 2021 ...IDA MOVING NORTHWESTWARD OVER SOUTHEASTERN LOUISIANA... ...CATASTROPHIC STORM SURGE, EXTREME WINDS, AND FLASH FLOODING CONTINUES IN PORTIONS OF SOUTHEASTERN LOUISIANA... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...29.5N 90.6W ABOUT 45 MI...75 KM SW OF NEW ORLEANS LOUISIANA ABOUT 70 MI...115 KM SSE OF BATON ROUGE LOUISIANA MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H PRESENT MOVEMENT...NW OR 325 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...938 MB...27.70 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Hurricane Warning along the coast of Louisiana from Morgan City to Intracoastal City has been changed to a Tropical Storm Warning. The Tropical Storm Warning from Cameron to Intracoastal City Louisiana has been discontinued. The Storm Surge Warning west of Morgan City has been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Morgan City Louisiana to the Alabama/Florida border * Lake Borgne, Lake Pontchartrain, Lake Maurepas, and Mobile Bay A Hurricane Warning is in effect for... * Morgan City Louisiana to the Mouth of the Pearl River * Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans A Tropical Storm Warning is in effect for... * Intracoastal City Louisiana to west of Morgan City Louisiana * Mouth of the Pearl River 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 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 Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 400 PM CDT (2100 UTC), the eye of Hurricane Ida was located near latitude 29.5 North, longitude 90.6 West. Ida is moving toward the northwest near 10 mph (17 km/h). A turn toward the north is expected overnight, followed by a slightly faster northeastward motion by Monday night and Tuesday. On the forecast track, the center of Ida will move farther inland over southeastern Louisiana tonight. Ida is then forecast to move well inland over portions of western Mississippi Monday and Monday night, and move across the Tennessee Valley on Tuesday. Doppler radar data indicate that the maximum sustained winds are near 130 mph (215 km/h) with higher gusts. Ida is an extremely dangerous category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Rapid weakening is expected during the next day or so, however Ida is forecast to remain a hurricane through late tonight and remain a tropical storm until Monday afternoon. Hurricane-force winds extend outward up to 45 miles (75 km) from the center and tropical-storm-force winds extend outward up to 150 miles (240 km). A Weatherflow station near Dulac just reported sustained winds of 93 mph (150 km/h) and a gust to 135 mph (217 km/h). A Florida Coastal Monitoring Program observing station at the South Lafourche airport recently reported a sustained wind of 91 mph (146 km/h) and wind gust of 122 mph (196 km/h). A sustained wind of 51 mph (81 km/h) and a gust to 82 mph (131 km/h) was recently reported at Lakefront Airport in New Orleans. The estimated minimum central pressure is 938 mb (27.70 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Ida can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC, and on the web at hurricanes.gov/graphics_at4.shtml?key_messages. 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... Port Fourchon, LA to Mouth of the Mississippi River...12-16 ft Morgan City, LA to Port Fourchon, LA...8-12 ft Mouth of the Mississippi River to Bay St. Louis, MS including Lake Borgne...8-12 ft Bay St. Louis, MS to Ocean Springs, MS...5-8 ft Lake Pontchartrain...5-8 ft Ocean Springs, MS to MS/AL border...4-7 ft Lake Maurepas...4-6 ft MS/AL border to AL/FL border including Mobile Bay...3-5 ft Intracoastal City, LA to Morgan City, LA including Vermilion Bay...1-3 ft AL/FL border to Okaloosa/Walton County Line including Pensacola Bay...1-3 ft Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher than those shown above. The deepest water will occur along the immediate coast near and to the east of the landfall location, 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: Catastrophic wind damage is likely near the core of Ida as it moves inland over southeastern Louisiana through this evening. Hurricane conditions will spread farther inland within the Hurricane Warning area over southeastern Louisiana tonight. Tropical storm conditions will also spread inland over portions of Louisiana and Mississippi tonight and Monday. RAINFALL: Heavy rainfall from Ida will continue to impact the southeast Louisiana coast, spreading northeast into the Lower Mississippi Valley this evening into Monday. Total rainfall accumulations of 10 to 18 inches with isolated maximum amounts of 24 inches are possible across southeast Louisiana into far southern Mississippi through Monday. This is likely to result in life- threatening flash and urban flooding and significant river flooding impacts. Ida is forecast to turn to the northeast on Monday and track across the Middle Tennessee Valley and Upper Ohio Valley through Wednesday, producing the following rainfall totals: Coastal Alabama to the far western Florida panhandle: 5 to 10 inches with isolated maximum amounts of 15 inches, today through Tuesday morning. Central Mississippi: 4 to 8 inches with isolated maximum amounts of 12 inches, tonight through Monday night. Middle Tennessee Valley, Upper Ohio Valley, Central Appalachians into the Mid-Atlantic: 3 to 6 inches with isolated higher amounts, Tuesday into Wednesday. These rainfall totals will result in considerable flash flooding along with widespread minor to isolated major riverine flooding from the Lower Mississippi Valley into far western Alabama. TORNADOES: Tornadoes will be most likely through Monday over southeast Louisiana, southern Mississippi, southwest Alabama, and the western Florida Panhandle. A few tornadoes are also possible farther north across much of Mississippi and Alabama on Monday. SURF: Swells will continue to affect the northern Gulf coast through early Monday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
