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Tropical Storm Ida Forecast Discussion Number 18
2021-08-30 16:54:31| National Hurricane Center (Atlantic)
Issued at 1000 AM CDT Mon Aug 30 2021 000 WTNT44 KNHC 301454 TCDAT4 Tropical Storm Ida Discussion Number 18 NWS National Hurricane Center Miami FL AL092021 1000 AM CDT Mon Aug 30 2021 The center of Ida has moved farther inland over western Mississippi this morning and NWS Doppler radar velocities and surface observations indicate that the tropical cyclone's winds have continued to decrease. The strongest winds are located in a band well southeast of the center along the coasts of Mississippi and Alabama where recent surface reports indicate 30-35 kt winds are still occurring. Therefore, the initial intensity is set at 35 kt. As Ida's circulation moves farther inland, additional weakening is expected and Ida is expected to become a tropical depression this afternoon. Continued weakening should occur while Ida moves over the Tennessee Valley on Tuesday, and the system is forecast to become extratropical over the eastern United States by late Wednesday. The global models indicate that the post-tropical cyclone will be absorbed by a frontal zone over the western Atlantic by the end of the forecast period. Ida is moving moving just east of due north or 010/8 kt. A north-northeastward turn should occur later today, followed by a faster northeastward motion tonight and Tuesday as a mid- to upper-level trough approaches the cyclone from the west. The dynamical model guidance remains tightly clustered with very little cross-track spread, although there remains some speed or along-track spread in the guidance. The NHC forecast is near the HCCA and TCVA consensus models. Key Messages: 1. Dangerous storm surge inundation will continue into this afternoon along portions of the coasts of Mississippi and Alabama. 2. Tropical storm force winds, especially in gusts, will continue over portions of southeastern Louisiana, southern Mississippi and southern Alabama this afternoon. 3. Ida will continue to produce heavy rainfall tonight through Tuesday morning across portions of southeast Louisiana, Mississippi, and western Alabama, resulting in considerable flash and urban flooding and significant river flooding impacts. Rivers in the Lower Mississippi Valley will remain elevated into next week. As Ida moves inland, additional considerable flooding impacts are likely across portions of the Tennessee Valley, the Ohio Valley, and particularly in the Central and Southern Appalachians into the Mid-Atlantic through Wednesday. 4. In areas that experienced damage and power loss, individuals should use extreme caution during the recovery phase. Post-storm fatalities and injuries often result from heart attacks, heat exhaustion, accidents related to clean up and recovery, and carbon monoxide poisoning from improper generator use. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 31.9N 90.7W 35 KT 40 MPH...INLAND 12H 31/0000Z 33.1N 90.1W 30 KT 35 MPH...INLAND 24H 31/1200Z 34.5N 88.4W 25 KT 30 MPH...INLAND 36H 01/0000Z 35.8N 85.9W 20 KT 25 MPH...INLAND 48H 01/1200Z 37.5N 82.5W 20 KT 25 MPH...POST-TROP/INLAND 60H 02/0000Z 38.9N 78.7W 20 KT 25 MPH...POST-TROP/EXTRATROP 72H 02/1200Z 39.5N 75.7W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 03/1200Z 40.5N 70.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 04/1200Z...DISSIPATED $$ Forecaster Brown
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