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| #1191896 (Received by flhurricane at: 4:51 AM 04.Aug.2024) TCDAT4 Tropical Storm Debby Discussion Number 8 NWS National Hurricane Center Miami FL AL042024 500 AM EDT Sun Aug 04 2024 Debby continues to slowly strengthen over the southeastern Gulf of Mexico. Deep convection is gradually expanding over the center and in fragmented bands on the system's east side. Some of the outer bands are moving through portions of the Lower Florida Keys and southwestern Florida, producing tropical-storm-force gusts. The initial wind speed is nudged upward to 45 kt, in agreement with the Dvorak classification from TAFB. Both the NOAA and Air Force Hurricane Hunter aircraft are scheduled to investigate the storm today, and that data will provide very helpful information to evaluate Debby's strength and structure. Debby continues to gradually turn to the right, with the initial motion now estimated to be north-northwestward at 11 kt. The storm is currently located on the southwestern periphery of an Atlantic mid-level ridge, and it is headed toward a weakness caused by a mid- to upper-level trough over the eastern U.S. This steering pattern should cause Debby to turn northward and then north-northeastward during the next day or so, taking the core of the cyclone to the Big Bend region of Florida early Monday. There is high confidence on this scenario, and little change has been made to that portion of the track forecast. While Debby moves across the very warm waters of the eastern Gulf of Mexico and remains in a relatively low wind shear environment, the storm will have an opportunity to strengthen rapidly before reaching the coast. The reliable intensity models all suggest significant strengthening, and the degree of intensification will be most related to how quickly Debby develops an inner core. The NHC intensity forecast remains near the high end of the intensity guidance through landfall, and shows Debby becoming a hurricane by tonight prior to landfall. After Debby makes landfall in Florida, the system is expected to slow down and turn northeastward across northern Florida and southeastern Georgia on Monday and Tuesday as the steering currents weaken significantly. There is a lot of model disagreement in whether or not the center of Debby stays inland or moves off the coast of the southeast U.S. by the middle of the week. But, a building ridge should cause it to turn northward or northwestward and likely back inland during the middle and latter portions of the week. Although confidence is low in the details of this portion of the track forecast, the complex and weak steering pattern suggests that Debby will be moving quite slowly and likely erratically while near or over the southeastern U.S., resulting in a potentially significant flooding event. Since it is not clear if the center will remain inland or move offshore for a period of time, the intensity forecast is also of low confidence. For now, little overall change to the intensity forecast was made, and it shows Debby remaining a tropical storm while meandering near the southeast U.S. Key Messages: 1. Heavy rainfall will likely result in considerable flash and urban flooding across portions of northern Florida through Friday morning. Potentially historic heavy rainfall across southeast Georgia and South Carolina through Friday morning will likely result in areas of severe and widespread flash and urban flooding. Significant river flooding is also expected. 2. Hurricane conditions are expected on Monday along portions of the Florida Big Bend region where a Hurricane Warning is in effect, with tropical storm conditions beginning this evening. Tropical storm conditions are expected through Monday farther south within the Tropical Storm Warning along Florida's west coast, including the Tampa Bay area and the Lower Florida Keys. 3. There is a danger of life-threatening storm surge inundation along portions of the Gulf coast of Florida from Aripeka to Indian Pass. Life-threatening storm surge is possible south of Aripeka to Bonita Beach, including Tampa Bay and Charlotte Harbor. 4. Impacts from storm surge and strong winds are possible elsewhere in Florida and along the southeast coast of the United States from Georgia to North Carolina through the middle of the week, and interests in those areas should continue to monitor the progress of this system. Additional watches and warnings will likely be required later today. FORECAST POSITIONS AND MAX WINDS INIT 04/0900Z 25.5N 84.0W 45 KT 50 MPH 12H 04/1800Z 27.2N 84.4W 60 KT 70 MPH 24H 05/0600Z 28.9N 84.4W 75 KT 85 MPH 36H 05/1800Z 30.2N 83.8W 65 KT 75 MPH...INLAND 48H 06/0600Z 30.9N 83.0W 40 KT 45 MPH...INLAND 60H 06/1800Z 31.6N 82.0W 40 KT 45 MPH...INLAND 72H 07/0600Z 31.7N 80.9W 45 KT 50 MPH...OVER WATER 96H 08/0600Z 32.4N 80.4W 45 KT 50 MPH...OVER WATER 120H 09/0600Z 34.3N 80.0W 35 KT 40 MPH...INLAND $$ Forecaster Cangialosi |
