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| #1016823 (Received by flhurricane at: 5:02 AM 15.Sep.2020) TCPAT4 BULLETIN Hurricane Sally Advisory Number 16 NWS National Hurricane Center Miami FL AL192020 400 AM CDT Tue Sep 15 2020 ...HISTORIC FLOODING IS POSSIBLE FROM SALLY WITH EXTREME LIFE- THREATENING FLASH FLOODING LIKELY THROUGH WEDNESDAY ALONG PORTIONS OF THE NORTHERN GULF COAST... SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...28.9N 88.1W ABOUT 60 MI...100 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER ABOUT 115 MI...185 KM SSE OF BILOXI MISSISSIPPI MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...983 MB...29.03 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Hurricane Warning has been replaced by a Tropical Storm Warning from the Mouth of the Pearl River westward to Grand Isle Louisiana, including Lake Pontchartrain, Lake Maurepas, and metropolitan New Orleans. The Tropical Storm Warning has been discontinued west of Grand Isle. The Storm Surge Warning between Port Fourchon and the Mouth of the Mississippi River has been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Mouth of the Mississippi River to the Okaloosa/Walton County Line Florida * Mobile Bay A Hurricane Warning is in effect for... * East of the Mouth of the Pearl River to the Navarre Florida A Tropical Storm Warning is in effect for... * East of Navarre Florida to Indian Pass Florida * Mouth of the Pearl River westward to Grand Isle Louisiana, including Lake Pontchartrain and Lake Maurepas and metropolitan New Orleans 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. 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 within 36 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 Sally was located an Air Force Reserve reconnaissance aircraft and NOAA Doppler weather radars near latitude 28.9 North, longitude 88.1 West. Sally is moving toward the west-northwest near 2 mph (4 km/h), and this general motion is expected to continue this morning. A northward turn is expected this afternoon, followed by a slow north-northeastward to northeastward motion tonight and continuing through Wednesday night. On the forecast track, the center of Sally will move near the coast of southeastern Louisiana later today, and make landfall in the hurricane warning area tonight or Wednesday morning. Data from the reconnaissance aircraft indicate that maximum sustained winds have decreased to near 85 mph (140 km/h) with higher gusts. Although little change in strength is forecast until landfall occurs, Sally is still expected to be a dangerous hurricane when it moves onshore along the north-central Gulf coast. Hurricane-force winds extend outward up to 45 miles (75 km) from the center and tropical-storm-force winds extend outward up to 125 miles (205 km). The estimated minimum central pressure based on data from the Air Force Hurricane Hunter aircraft is 983 mb (29.03 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Sally can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml 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... Mouth of the Mississippi River to Dauphin Island including Lake Borgne...6-9 ft Mobile Bay...6-9 ft Dauphin Island to AL/FL Border...4-7 ft AL/FL Border to Okaloosa/Walton County Line including Pensacola Bay and Choctawhatchee Bay...2-4 ft Lake Pontchartrain and Lake Maurepas...2-4 ft Port Fourchon to Mouth of the Mississippi River...1-3 ft Okaloosa/Walton County Line to Chassahowitzka including Saint Andrew 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 in areas of onshore winds, where the surge will be accompanied by large and damaging 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 to begin within the hurricane warning area this late afternoon or tonight. Tropical storm conditions are occurring in portions of the warning area across the western Florida Panhandle and Alabama, and these conditions will gradually spread westward this morning and continue into Wednesday. RAINFALL: Sally is expected to be a slow moving system as it approaches land producing 10 to 20 inches of rainfall with isolated amounts of 30 inches along and just inland of the central Gulf Coast from the western Florida Panhandle to far southeastern Mississippi. Historic flooding is possible with extreme life-threatening flash flooding likely through Wednesday. In addition, this rainfall will lead to widespread moderate to major flooding on area rivers. Sally is forecast to turn inland early Wednesday and move across the Southeast producing rainfall of 4 to 8 inches, with isolated maximum amounts of 12 inches, across portions of southeastern Mississippi, southern and central Alabama, northern Georgia, and the western Carolinas. Significant flash and urban flooding is likely, as well as widespread minor to moderate flooding on some rivers. TORNADOES: A tornado or two will be possible this morning in coastal areas of the Florida Panhandle and Alabama. The tornado threat should increase and slowly spread inland the rest of today into Wednesday. SURF: Swells from Sally will continue to affect the coast from the Florida Big Bend westward to southeastern Louisiana during 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. NEXT ADVISORY ------------- Next intermediate advisory at 700 AM CDT. Next complete advisory at 1000 AM CDT. $$ Forecaster Stewart |