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| #1059220 (Received by flhurricane at: 7:59 AM 29.Aug.2021) TCDAT4 Hurricane Ida Special Discussion Number 13 NWS National Hurricane Center Miami FL AL092021 700 AM CDT Sun Aug 29 2021 Recent reports from both NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that Ida has continued to strengthen since the 0900 UTC advisory and the maximum winds are estimated to be 130 kt. This intensity is based on peak 700-mb flight-level winds of 146 kt that have been reported by both aircraft and believable SFMR winds of around 130 kt. The NOAA aircraft very recently reported that the minimum pressure has fallen to around 933 mb. This special advisory is issued to raise the 12-hour forecast intensity to 135 kt, but it is possible that Ida could peak slightly above that before landfall occurs. The initial motion estimate is 320/13 kt, slightly faster than the previous forecast. Therefore, the 12-hour forecast point has also been adjusted slightly. No other changes were made to the track or intensity forecasts. The initial and forecast 64-kt wind radii were adjusted outward in the northeast and southeast quadrants based on aircraft data. Note that this Special advisory replaces the regular 1200 UTC (700 AM CDT) intermediate public advisory. Key Messages: 1. Extremely life-threatening storm surge inundation of 9 feet or greater above ground level is imminent somewhere within the area from 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. Interests throughout the Storm Surge Warning area should follow any advice given by local officials. 2. Catastrophic wind damage is likely where the core of Ida moves onshore along the southeast coast of Louisiana in the next few hours. Hurricane-force winds are expected today within the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans. 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 today through 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 river 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 29/1200Z 28.5N 89.6W 130 KT 150 MPH 12H 29/1800Z 29.2N 90.4W 135 KT 155 MPH 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 Brown/Brennan |
