ZCZC MIATCPAT4 ALL TTAA00 KNHC DDHHMM  BULLETIN Tropical Storm Ida Advisory Number  17 NWS National Hurricane Center Miami FL       AL092021 400 AM CDT Mon Aug 30 2021  ...IDA NOW A TROPICAL STORM OVER SOUTHWESTERN MISSISSIPPI... ...DANGEROUS STORM SURGE, DAMAGING WINDS, AND FLASH FLOODING CONTINUE OVER PORTIONS OF SOUTHEASTERN LOUISIANA AND SOUTHERN MISSISSIPPI...   SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...31.0N 90.8W ABOUT 95 MI...155 KM SSW OF JACKSON MISSISSIPPI ABOUT 50 MI...75 KM NNE OF BATON ROUGE LOUISIANA MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H PRESENT MOVEMENT...N OR 355 DEGREES AT 8 MPH...13 KM/H MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES   WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY:  The Storm Surge Warning has been discontinued from Morgan City to Grand Isle, Louisiana.  The Hurricane and Tropical Storm Warnings have been discontinued west of Grand Isle, Louisiana.  The Hurricane Warning has been replaced with a Tropical Storm Warning from Grand Isle to the Mouth of the Pearl River, including Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans.  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. 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 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 AM CDT (0900 UTC), the center of Tropical Storm Ida was  located by NOAA Doppler weather radars, satellite data, and surface  observations near latitude 31.0 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  southeastern Louisiana early this morning and move into southwestern  Mississippi later 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 near 60 mph (95 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 by  this evening.  Tropical-storm-force winds extend outward up to 150 miles (240 km),  mainly southeast of the center. A sustained wind of 32 mph (51 km/h)  and a gust to 52 mph (84 km/h) were recently observed at the airport  in McComb, Mississippi. Along the Gulf coast, a Weatherflow station  in Gulfport, Mississippi, recently measured a sustained wind of 46  mph (74 km/h) and a gust to 66 mph (106 km/h).  The estimated minimum central pressure is 990 mb (29.24 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...  Pointe a la Hache, LA to Bay St. Louis, MS including Lake Borgne..4-7 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:  Wind damage is likely near the core of Ida as it moves farther inland over southwestern Mississippi during the next few hours.  Tropical storm conditions will continue to spread inland over portions of Louisiana and Mississippi through this morning.  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 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.   NEXT ADVISORY ------------- Next intermediate advisory at 700 AM CDT. Next complete advisory at 1000 AM CDT.  $$ Forecaster Stewart  NNNN