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| #1192091 (Received by flhurricane at: 10:57 PM 04.Aug.2024) TCDAT4 Hurricane Debby Discussion Number 11 NWS National Hurricane Center Miami FL AL042024 1100 PM EDT Sun Aug 04 2024 NWS Doppler Radar imagery from both Tampa and Tallahassee along with reports from both NOAA and Air Force hurricane hunter aircraft indicate that Debby's structure has continued to improve this evening with a ragged eye becoming apparent. Both NOAA and Air Force reconnaissance aircraft have found strong flight-level winds in the convective band located well to the east-northeast of the center, with the Air Force plane measuring 700-mb flight-level winds in the 75-77 kt range. Recent dropsonde data has shown that the pressure has fallen to around 985 mb. Based on these data, Debby is being upgraded to a 65-kt hurricane at this time. Although the inner core is still somewhat ragged, the storm's structure has improved and additional strengthening appears likely overnight and early Monday while Debby moves over waters of high heat content in the eastern Gulf of Mexico and within a favorable upper-level wind environment. The NHC intensity forecast is again at the high end of the intensity guidance. Weakening is expected while Debby moves inland over the southeastern United States. Some restrengthening is forecast when Debby moves over the western Atlantic, but there is still higher-than-normal uncertainty in this portion of the forecast. There has been no change to the track forecast philosophy. Debby should continue to move generally northward overnight and early Monday through a weakness in the subtropical ridge caused by a mid-level trough over the eastern United States. This motion is expected to bring the center onshore along the coast of the northeastern Gulf of Mexico on Monday. After that time, the trough is forecast to move eastward causing the steering currents to weaken over the southeastern United States. This will result in a significant slowdown of Debby's forward motion, and the model spread increases significantly in the 72-120 h time period. Regardless of Debby's exact forecast track during that time, the slow forward speed is likely to cause potentially historic rainfall across southeast Georgia and South Carolina, with an increasing likelihood of catastrophic flooding. Key Messages: 1. Potentially historic heavy rainfall across southeast Georgia and South Carolina through Friday morning will likely result in areas of catastrophic flooding. Heavy rainfall will likely result in considerable flooding impacts from portions of central and northern Florida through the Coastal Plain of the Carolinas through Friday. 2. There is a danger of life-threatening storm surge along portions of the Gulf Coast of Florida, with 6 to 10 feet of inundation above ground level expected somewhere between Ochlockonee River to Yankeetown late tonight and Monday morning. Residents in the Storm Surge Warning area should follow any advice given by local officials. 3. Hurricane conditions are expected 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 area along Florida's west coast, including the Tampa Bay area. 4. Dangerous storm surge and wind impacts are expected along portions of the southeast U.S. coast from northeastern Florida to North Carolina through the middle of the week, and storm surge warnings and tropical storm watches and warnings have been issued for portions of these areas. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 28.6N 84.0W 65 KT 75 MPH 12H 05/1200Z 29.8N 83.8W 75 KT 85 MPH 24H 06/0000Z 30.8N 83.0W 50 KT 60 MPH...INLAND 36H 06/1200Z 31.5N 82.1W 40 KT 45 MPH...INLAND 48H 07/0000Z 31.6N 81.0W 35 KT 40 MPH...OVER WATER 60H 07/1200Z 31.7N 80.1W 40 KT 45 MPH 72H 08/0000Z 32.1N 79.8W 45 KT 50 MPH 96H 09/0000Z 33.0N 79.8W 45 KT 50 MPH...INLAND 120H 10/0000Z 34.7N 79.6W 30 KT 35 MPH...INLAND $$ Forecaster Brown |
