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