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| #1150292 (Received by flhurricane at: 7:46 AM 30.Aug.2023) TCDAT5 Hurricane Idalia Discussion Number 15 NWS National Hurricane Center Miami FL AL102023 500 AM EDT Wed Aug 30 2023 Idalia continues to undergo rapid intensification. Maximum flight-level winds were 123 kt, with believable SFMR values of 115 kt. Satellite images show a small eye surrounded by very cold clouds tops, especially in the western quadrant. The initial wind speed is set to 115 kt, making Idalia an extremely dangerous category 4 hurricane. The hurricane still has a few hours left to intensify before it makes landfall. The biggest change to the intensity forecast is to increase the wind speeds over southeastern Georgia and South Carolina as the rapid motion and track close to the coast is expected to keep the system near hurricane strength for longer. Thus a Hurricane Warning has been issued for a portion of those coasts, and the Hurricane Watch is extended northeastward. After the hurricane moves offshore, the wind field on the northwestern side near eastern North Carolina is expected to be enhanced by a cold front, and the Tropical Storm Watch has been upgraded to a Tropical Storm Warning in that area. The long-range intensity forecast is quite uncertain with Idalia taking on some hybrid characteristics due to a baroclinc trough. No changes were made at this time, and the forecast remains close to the consensus. Idalia is moving faster toward the north-northeast or 025/16 kt. After landfall, Idalia is expected to move near or along the coast of Georgia and the Carolinas in 24-36 hours. Uncertainty in the track forecast beyond 48 hours remains quite large, and the latest guidance is significantly faster. The new forecast is adjusted toward the consensus, but could be too slow at long range. KEY MESSAGES: 1. Catastrophic impacts from storm surge inundation of 12 to 16 feet above ground level and destructive waves are expected somewhere between the Wakulla/Jefferson County line and Yankeetown, Florida. Life-threatening storm surge inundation is likely elsewhere along portions of the Florida Gulf Coast where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials. 2. Destructive life-threatening winds will occur where the core of Idalia moves onshore in the Big Bend region of Florida, with hurricane conditions expected elsewhere in portions of the Hurricane Warning area along the Florida Gulf Coast. Strong winds will also spread inland across portions of northern Florida and southern Georgia near the track of the center of Idalia where Hurricane Warnings are in effect. Residents in these areas should be prepared for long-duration power outages. Damaging hurricane-force winds are likely in portions of eastern Georgia and southeastern South Carolina where Hurricane Warnings are now in effect. 3. Areas of flash, urban, and moderate river flooding, with considerable impacts, are expected from the Florida Big Ben through, central Georgia and South Carolina, through eastern North Carolina into Thursday. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 29.1N 84.1W 115 KT 130 MPH 12H 30/1800Z 31.0N 82.7W 85 KT 100 MPH...INLAND 24H 31/0600Z 33.1N 79.6W 60 KT 70 MPH...INLAND 36H 31/1800Z 33.8N 76.1W 50 KT 60 MPH...OVER WATER 48H 01/0600Z 33.3N 72.7W 50 KT 60 MPH 60H 01/1800Z 32.4N 70.7W 45 KT 50 MPH 72H 02/0600Z 31.5N 69.5W 45 KT 50 MPH 96H 03/0600Z 30.7N 68.0W 45 KT 50 MPH 120H 04/0600Z 30.5N 66.0W 45 KT 50 MPH $$ Forecaster Blake |
