...DANGEROUS STORM SURGE AND FLASH FLOODING CONTINUES OVER PORTIONS OF SOUTHEASTERN LOUISIANA, SOUTHERN MISSISSIPPI, AND SOUTHERN ALABAMA...
Tropical Storm Ida Intermediate Advisory Number 17A
NWS National Hurricane Center Miami FL AL092021
700 AM CDT Mon Aug 30 2021
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
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LOCATION...31.5N 90.8W
ABOUT 65 MI...105 KM SSW OF JACKSON MISSISSIPPI
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.32 INCHES
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
*Grand Isle, Louisiana, to the Alabama/Florida border
A Tropical Storm Warning is in effect for...
* Grand Isle, Louisiana, to the Alabama/Florida border, including Lake Pontchartrain, 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 in the indicated locations. 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 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
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At 700 AM CDT (1200 UTC), the center of Tropical Storm Ida was located by NOAA Doppler weather radars, satellite data, and surface observations near latitude 31.5 North, longitude 90.8 West. Ida is moving toward the north near 8 mph (13 km/h), and this general motion is forecast to continue today. A faster northeastward motion is expected to begin by tonight and continue on Tuesday. On the forecast track, the center of Ida will move farther inland over southwestern Mississippi this morning. Ida is then forecast to move over central and northeastern Mississippi this afternoon and tonight, and move across the Tennessee Valley on Tuesday.
Maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts. Additional rapid weakening is forecast during the next day or so, and Ida is expected to become a tropical depression this afternoon.
Tropical-storm-force winds extend outward up to 150 miles (240 km), mainly southeast of the center over water. A coastal marine observing site at Dauphin Island, Alabama, recently reported sustained winds of 38 mph (61 km/h) and a gust to 46 mph (74 km/h). A wind gust to 45 mph (72 km/h) was recently measured at Biloxi, Mississippi.
The estimated minimum central pressure is 993 mb (29.32 inches).
HAZARDS AFFECTING LAND
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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...
Pointe a la Hache, LA to Bay St. Louis, MS including Lake Borgne...4-6 ft
Lake Maurepas and Lake Pontchartrain...4-6 ft
Bay St. Louis, LA to AL/FL border including Mobile Bay...3-5 ft
Grand Isle, LA to Pointe a la Hache, LA...2-4 ft
Morgan City, LA to Grand Isle, 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: Tropical storm conditions will continue over portions of Louisiana, southern Mississippi, and southern Alabama through this morning or early afternoon.
RAINFALL: Through Tuesday morning, Ida will produce additional rainfall totals of 4 to 8 with localized higher amounts possible across portions of southeast Louisiana into far southern Mississippi. Storm total rainfall accumulations of 10 to 18 inches with isolated maximum amounts of 24 inches is expected. Heavy rain combined with storm surge has resulted in catastrophic impacts along the southeast coast of Louisiana with life threatening flash flooding and significant riverine flooding continuing farther inland.
Ida is expected to turn northeast this morning and is forecast to track across the Middle Tennessee Valley, Ohio Valley and Mid-Atlantic through Wednesday, producing the following rainfall totals:
Coastal Alabama to the far western Florida panhandle: An additional 4 to 8 inches resulting in storm total accumulations of 6 to 12 inches with isolated maximum amounts of 15 inches, today through Tuesday morning.
Central Mississippi into far western Alabama: 4 to 8 inches with isolated maximum amounts of 12 inches, today through tonight.
Middle Tennessee Valley, Ohio Valley, Central/Southern Appalachians into the Mid-Atlantic: 3 to 6 inches with isolated higher amounts, Tuesday into Wednesday.
Considerable flash flooding is possible from the Lower Mississippi Valley through the Middle Tennessee Valley, Ohio Valley, Central/Southern Appalachians, and into the Mid-Atlantic. Widespread minor to isolated major riverine flooding is possible from the Lower Mississippi Valley into far western Alabama through Wednesday.
TORNADOES: A few tornadoes are possible today into tonight, mainly across southeast Mississippi, southwest Alabama, and the western Florida Panhandle.
SURF: Swells will continue to affect portions of the northern Gulf coast through today. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
Forecaster Brown
