Tropical Storm Debby Discussion Number  22
NWS National Hurricane Center Miami FL       AL042024
Issued by the NWS Weather Prediction Center College Park MD
500 PM EDT Wed Aug 07 2024

Debby is producing small, broken bands of convection around its
center this afternoon. The storm continues to meander around NOAA
buoy 41004, and data from that station indicate the central pressure
remains around 995 mb. The Air Force Hurricane Hunters reported peak
SFMR winds of 47 kt within convection to the northeast of the center
during their last pass through the storm a few hours ago. Based on
these data and the earlier flight-level winds, the initial intensity
is held at 50 kt.

Although the storm is moving over warm waters, it lacks an inner
core and has a large radius of maximum wind. Therefore, only modest
strengthening is forecast during the next 12 h while the system
approaches South Carolina, in best agreement with some of the
statistical guidance. Once inland, Debby is expected to quickly lose
tropical characteristics and weaken. The interaction of Debby with
the upper trough will lead to a baroclinic transition as the low
merges with a frontal zone and becomes extratropical. The NHC
forecast shows this occurring by Friday. However, it is important to
note that these changes do not diminish the threat of heavy rainfall
and flooding across portions of the Carolinas, Mid-Atlantic, and
northeastern United States during the next few days.

The long-term motion of Debby is a north-northeastward drift within 
weak steering currents between two subtropical high pressure areas. 
However, more recent fixes suggest the system may be turning 
northward as expected, with a ridge beginning to build to the east 
of Debby over the western Atlantic. Thus, a north-northwestward to 
northward motion is expected through tonight while Debby approaches 
the coast of South Carolina. After landfall, Debby will become 
caught in southerly to southwesterly flow ahead of a mid-latitude 
trough near the Great Lakes region. This will cause the storm to 
accelerate north-northeastward to northeastward on Friday and into 
the weekend. With the guidance in good agreement on this scenario, 
little change was made to the updated NHC track forecast.


Key Messages:

1. Heavy rainfall across portions of the Carolinas is expected to
persist through Thursday along with areas of considerable flooding.
Expected heavy rainfall will also result in considerable flooding
impacts across portions of the Mid-Atlantic States and Northeast
through Saturday morning.

2. Tropical storm conditions will affect portions of the South
Carolina and North Carolina coast through Thursday. Tropical storm
warnings and watches are in effect for portions of that area.

3. Coastal flooding due to storm surge is likely along portions of
the South Carolina and North Carolina coastline through Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 32.5N  79.1W   50 KT  60 MPH
12H  08/0600Z 33.1N  79.4W   55 KT  65 MPH...NEAR THE COAST
24H  08/1800Z 34.3N  79.8W   40 KT  45 MPH...INLAND
36H  09/0600Z 36.2N  79.8W   30 KT  35 MPH...POST-TROPICAL
48H  09/1800Z 39.8N  77.6W   30 KT  35 MPH...POST-TROP/EXTRATROP
60H  10/0600Z 44.3N  73.1W   30 KT  35 MPH...POST-TROP/EXTRATROP
72H  10/1800Z 48.8N  67.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
96H  11/1800Z 53.0N  56.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  12/1800Z...DISSIPATED

$$
Forecaster Reinhart