Tropical Depression Four Discussion Number   5
NWS National Hurricane Center Miami FL       AL042024
1100 AM EDT Sat Aug 03 2024

Tropical Depression Four has become somewhat better organized this 
morning, with the circulation becoming better defined over western 
Cuba and curved convective bands forming close to the center in the 
southern semicircle.  However, the circulation is still somewhat 
elongated with multiple low-level vorticity centers rotating around 
the mean center.  The initial intensity has been increased to 30 kt 
based on surface observations in the Florida Keys and a satellite 
intensity estimate from TAFB.

The depression appears to be starting its northwestward turn with 
the initial motion now 300/13 kt.  A large mid- to upper-level 
trough over the central United States is creating a break in the 
subtropical ridge, and the cyclone is expected to turn northward 
into this break by 24-36 h.  This should be followed by a gradual 
turn toward the northeast through 60 h.  This motion should bring 
the center near or over the northern Gulf coast in roughly 48 h.  
After landfall, weakening steering currents should cause the cyclone 
to slow down while it moves northeastward over parts of northern 
Florida and Georgia.  The uncertainty in the forecast increases 
significantly after 72 h as the cyclone interacts with a portion of 
the U.S. trough. The current GFS and ECMWF forecast the system to 
move into the Atlantic, and then turn back toward the southeastern 
U.S. coast by 120 h.  On the other hand, the Canadian model moves 
the cyclone slowly northeastward across the southeastern states and 
does not bring it over the Atlantic.  This portion of the new 
forecast track shows a slower forward motion than the previous track 
due to changes in the GFS forecast since the previous advisory.

After the system crosses Cuba and emerges over the eastern Gulf of
Mexico, the environmental and oceanic conditions appear favorable
for intensification.  Due to the lack of internal organization, the 
initial intensification is likely to be slow.  However, a faster 
rate of development is likely once the system gets better 
organized, and the cyclone is likely to be near or at hurricane 
strength when it reaches to the northern Gulf coast.  Weakening is 
forecast after landfall while the system moves over the 
southeastern United States. Beyond 72 h, the intensity forecast 
remains quite uncertain due to uncertainty of whether the center 
will reach the Atlantic and how much interaction will occur with 
the aforementioned mid-latitude trough interaction.


Key Messages:

1. Heavy rainfall will likely result in locally considerable flash 
and urban flooding across portions of Florida and the coastal areas 
of the Southeast this weekend through Thursday morning. River 
flooding is also expected.

2.  Hurricane conditions are possible late Sunday in portions of the 
Florida Gulf Coast and Big Bend region where a Hurricane Watch is in 
effect. Tropical storm conditions are expected farther south along 
FloridaG��s west coast, including the Tampa Bay area, and in the Dry 
Tortugas where Tropical Storm Warnings are in effect.

3. There is a danger of life-threatening storm surge inundation 
along portions of the west coast of Florida from Aripeka to the 
Aucilla River. Life-threatening storm surge is possible west of 
Aucilla River to Indian Pass and south of Aripeka to Bonita Beach, 
including Tampa Bay and Charlotte Harbor.

4. Impacts from storm surge, strong winds, and heavy rains are 
possible elsewhere in Florida and along the southeast coast of the 
United States from Georgia to North Carolina through the middle of 
next 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  03/1500Z 22.8N  82.0W   30 KT  35 MPH
12H  04/0000Z 24.3N  83.4W   30 KT  35 MPH
24H  04/1200Z 26.3N  84.3W   40 KT  45 MPH
36H  05/0000Z 28.2N  84.3W   50 KT  60 MPH
48H  05/1200Z 29.8N  83.8W   60 KT  70 MPH
60H  06/0000Z 30.7N  83.1W   40 KT  45 MPH...INLAND
72H  06/1200Z 31.4N  82.0W   35 KT  40 MPH...INLAND
96H  07/1200Z 31.5N  80.5W   40 KT  45 MPH...OVER WATER
120H  08/1200Z 32.5N  80.0W   55 KT  65 MPH

$$
Forecaster Beven