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Hurricane Ida Probabilistic Storm Surge Graphics

2021-08-29 11:33:39| National Hurricane Center (Atlantic)

Probabilistic Storm Surge Graphics last updated Sun, 29 Aug 2021 09:33:39 GMT

Hurricane Ida Public Advisory Number 12

2021-08-29 11:19:04| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Sun Aug 29 2021 000 WTNT34 KNHC 290918 CCA TCPAT4 BULLETIN Hurricane Ida Advisory Number 12...Corrected NWS National Hurricane Center Miami FL AL092021 400 AM CDT Sun Aug 29 2021 Corrected storm surge heights for Mississippi coast ...DANGEROUS CATEGORY 4 HURRICANE IDA STRENGTHENS SOME MORE... ...LIFE-THREATENING STORM SURGE, POTENTIALLY CATASTROPHIC WIND DAMAGE, AND FLOODING RAINFALL WILL IMPACT PORTIONS OF THE NORTHERN GULF COAST BEGINNING LATER THIS MORNING... SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...28.0N 89.1W ABOUT 75 MI...120 KM S OF THE MOUTH OF THE MISSISSIPPI RIVER ABOUT 145 MI...235 KM SE OF HOUMA LOUISIANA MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H PRESENT MOVEMENT...NW OR 315 DEGREES AT 15 MPH...24 KM/H MINIMUM CENTRAL PRESSURE...946 MB...27.94 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * East of Rockefeller Wildlife Refuge Louisiana to the Alabama/Florida border * Vermilion Bay, Lake Borgne, Lake Pontchartrain, Lake Maurepas, and Mobile Bay A Hurricane Warning is in effect for... * Intracoastal 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... * Cameron Louisiana to west of Intracoastal 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, 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 within the next 6 to 12 hours. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 to 24 hours. 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 AM CDT (0900 UTC), the center of Hurricane Ida was located near latitude 28.0 North, longitude 89.1 West. Ida is moving toward the northwest near 15 mph (24 km/h), and this general motion should continue through tonight and early Monday, followed by a slower northward motion on Monday afternoon. A northeastward turn is forecast by Monday night. On the forecast track, the center of Ida will continue moving across the north-central Gulf of Mexico this morning, and make landfall along the coast of southeastern Louisiana within the hurricane warning area this afternoon or evening. Ida is then forecast to move well inland over portions of Louisiana and western Mississippi on Monday and Monday night. Satellite and Doppler radar data indicate that maximum sustained winds have increased to near 140 mph (220 km/h) with higher gusts. Ida is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some additional strengthening is forecast, and Ida is expected to be an extremely dangerous major hurricane when it makes landfall along the Louisiana coast this afternoon. Rapid weakening is expected after landfall. Hurricane-force winds extend outward up to 40 miles (65 km) from the center and tropical-storm-force winds extend outward up to 140 miles (220 km). The estimated minimum central pressure is 946 mb (27.94 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 Burns Point, LA to Morgan City, LA...6-9 ft Bay St. Louis, MS to Ocean Springs, MS...6-9 ft Lake Pontchartrain...5-8 ft Ocean Springs, MS to MS/AL border...4-7 ft Intracoastal City, LA to Burns Point, LA including Vermilion Bay...4-6 ft Lake Maurepas...4-6 ft Pecan Island, LA to Intracoastal City, LA...2-4 ft MS/AL border to AL/FL border including Mobile Bay...3-5 ft Sabine Pass to Pecan Island, LA...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: Hurricane conditions are expected in the Hurricane Warning area along the Louisiana coast beginning by later this morning with tropical storm conditions expected to begin by early this morning. These conditions will spread inland over portions of Louisiana and Mississippi tonight and Monday. RAINFALL: Heavy rainfall from Ida will begin to impact the southeast Louisiana coast this morning, spreading northeast into the Lower Mississippi Valley later today 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 riverine flooding impacts. Ida is forecast to turn to the northeast early Monday and track across the Middle Tennessee Valley and 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 to the Ohio Valley: 3 to 6 inches with isolated higher amounts, Tuesday into Wednesday. These rainfall totals will result in considerable flash and riverine flooding. TORNADOES: Tornadoes will be possible today into Monday from southeast Louisiana across southeast Mississippi and southwest Alabama to the western Florida Panhandle. SURF: Swells are beginning to reach the northern Gulf coast and will continue to affect that area through Monday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 700 AM CDT. Next complete advisory at 1000 AM CDT. $$ Forecaster Stewart

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Hurricane Ida Forecast Discussion Number 12

2021-08-29 10:59:59| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Sun Aug 29 2021 000 WTNT44 KNHC 290859 TCDAT4 Hurricane Ida Discussion Number 12 NWS National Hurricane Center Miami FL AL092021 400 AM CDT Sun Aug 29 2021 Ida has undergone some dramatic inner-core structural changes since the previous advisory. The eye between 25,000-45,000 ft has become circular with a diameter of about 15 nmi now, and at least two eyewall mesocyclones have been noted rotating cyclonically around the eyewall in both radar and high-resolution 1-minute GOES-16 satellite imagery. The result has been rapid strengthening of at least 30 kt during the past 6 hours, along with a pressure drop of more than 15 mb during that same time, with a 6-mb decrease having occurred in the 1-hr period between about 0500-0600 UTC based on Air Force Reserve reconnaissance aircraft eye dropsonde data. The aircraft also measured a maximum 700-mb flight-level wind speed of 133 kt in the northeastern quadrant, along with a peak SFMR surface wind speed of 116 kt. Furthermore, NWS Doppler radar velocity data from Slidell, Louisiana, has recently been measuring velocities of 120-130 kt between 25,000-30,000 ft, which is quite rare, and indicates that Ida is a vertically deep and intense hurricane. Ida was initialized with 115 kt at 0600 UTC, but the 0900 UTC advisory intensity has been increased to 120 kt based on the 133-kt flight-level wind and the improved structure in both radar data and satellite imagery since the 0609 UTC time of that aircraft observation. The initial motion remains northwestward, or 315/13 kt. There is no significant change to the previous forecast track or synoptic reasoning. The subtropical ridge oriented east-west along 30N-31N across the southeastern U.S. is forecast to remain intact through the forecast period with only minor shifts in the location and strength of the ridge. As a result, Ida should continue to move northwestward toward the southeastern Louisiana coast today, followed by a gradual turn toward the north tonight after landfall. On Monday, the hurricane is expected to move northeastward across the Tennessee Valley when Ida moves north of the ridge axis. Impacts and hazards will arrive well before the eye of the hurricane makes landfall. Tropical-storm-force winds are likely to begin later this morning. Therefore, all preparations to protect life and property must be rushed to completion. The new track forecast is basically just an update of the previous advisory track. Ida will remain over waters with high oceanic heat content for another 6 hours or so. Thereafter, the heat content will drop sharply to less than half of the current value of more than 100 units. However, some additional strengthening is expected until landfall occurs. After Ida moves inland tonight, rapid weakening is forecast due to a combination of land interaction, entrainment of drier air, and some increase in westerly vertical wind shear. Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center. Rainfall impacts will also spread inland across the Lower Mississippi and Tennessee Valleys through early next week. Key Messages: 1. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana, Mississippi, and Alabama within the Storm Surge Warning area. Extremely life-threatening inundation of 9 feet or greater above ground level is possible somewhere within the area from Morgan City, Louisiana, to the coast of Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher. Interests throughout the warning area should follow any advice given by local officials. 2. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of southeastern Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area. 3. Damaging winds, especially in gusts, will spread inland near the track of the center of Ida across portions of southeastern Louisiana and southwestern Mississippi Sunday night and early Monday. These winds will likely lead to widespread tree damage and power outages. 4. Ida will produce heavy rainfall today through Monday across the central Gulf Coast from southeastern Louisiana, coastal Mississippi, to far southwestern Alabama resulting in considerable to life-threatening flash and urban flooding and significant riverine flooding impacts. As Ida moves inland, significant flooding impacts are possible across portions of the Lower Mississippi, Tennessee, and Ohio Valleys through Wednesday. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 28.0N 89.1W 120 KT 140 MPH 12H 29/1800Z 29.1N 90.3W 125 KT 145 MPH...NEAR SERN LOUISIANA 24H 30/0600Z 30.6N 91.1W 70 KT 80 MPH...INLAND 36H 30/1800Z 32.2N 91.0W 45 KT 50 MPH...INLAND 48H 31/0600Z 33.8N 90.0W 30 KT 35 MPH...INLAND 60H 31/1800Z 35.4N 87.9W 25 KT 30 MPH...INLAND 72H 01/0600Z 36.7N 85.2W 20 KT 25 MPH...INLAND 96H 02/0600Z 38.9N 78.9W 20 KT 25 MPH...POST-TROP/INLAND 120H 03/0600Z...DISSIPATED $$ Forecaster Stewart

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