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