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| #1059399 (Received by flhurricane at: 10:47 PM 29.Aug.2021) TCDAT4 Hurricane Ida Discussion Number 16 NWS National Hurricane Center Miami FL AL092021 1000 PM CDT Sun Aug 29 2021 Although Ida has been inland over southeastern Louisiana for several hours, it is still a very well organized hurricane. Doppler radar images indicate that the hurricane continues to have a well-defined eye, though the eyewall has become a bit ragged on the southwest side. Beyond the inner core, rain bands remain well established, especially on the system's east side. Earlier this evening, there were reports of extreme wind gusts over 120 kt along the coast of southeastern Louisiana. Based on Doppler radar velocity data over the past hour or two, the initial intensity is estimated to be 90 kt. As Ida continues inland, rapid weakening is expected due to a combination of land interaction and an increase in wind shear. However, damaging winds, especially in gusts, are expected to spread further inland over southeastern Louisiana and southwestern Mississippi through Monday morning. To account for this, the gust factor in the Forecast/Advisory has been adjusted accordingly. Ida is likely to weaken to a tropical storm by Monday morning and a tropical depression by Monday night. Some slight restrengthening as an extratropical storm is possible when Ida moves over the western Atlantic in 4 days or so. In addition, heavy rains will spread northward and then northeastward along the forecast track. Ida is expected to turn northward by early Monday as it moves in the flow on the western side of a subtropical ridge. A faster motion to the northeast is expected by Tuesday as a mid- to upper-level trough approaches the system, with that motion continuing through much of the remainder of the week. The NHC track forecast is a little to the south or right of the previous one to come into better agreement with the latest models. Key Messages: 1. Life-threatening storm surge inundation will continue through tonight along portions of the coast between Burns Point, Louisiana, to Ocean Springs, Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher. 2. Wind damage will occur near the core of Ida as it continues inland over southeastern Louisiana during the next few hours. Damaging winds, especially in gusts, will spread inland near the track of Ida's center into southwestern Mississippi through early Monday. These winds will likely lead to widespread tree damage and power outages. 3. Ida will continue to produce heavy rainfall tonight through Monday across southeast Louisiana, coastal Mississippi, and southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant riverine flooding impacts. As Ida moves farther inland, considerable flooding impacts are possible across portions of the Lower Mississippi Valley, Tennessee Valley, Upper Ohio Valley, Central Appalachians, and Mid-Atlantic through Wednesday. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 30.3N 90.7W 90 KT 105 MPH...INLAND 12H 30/1200Z 31.5N 90.8W 50 KT 60 MPH...INLAND 24H 31/0000Z 33.0N 90.1W 30 KT 35 MPH...INLAND 36H 31/1200Z 34.6N 88.5W 25 KT 30 MPH...INLAND 48H 01/0000Z 36.1N 85.9W 25 KT 30 MPH...POST-TROP/INLAND 60H 01/1200Z 37.5N 82.5W 25 KT 30 MPH...POST-TROP/INLAND 72H 02/0000Z 38.9N 78.8W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 03/0000Z 40.0N 72.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 04/0000Z 40.7N 67.9W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi |
