Tropical Storm Helene Discussion Number  16
NWS National Hurricane Center Miami FL       AL092024
500 AM EDT Fri Sep 27 2024

The eye of Helene made landfall near Perry, Florida, just after the 
last advisory was issued. Since then, the center has crossed the 
Florida Big Bend region and is currently located over east central 
Georgia.  Surface observations have shown steady weakening since 
landfall, and the maximum winds have decreased to a possibly 
generous 60 kt.  During the last couple of hours, the radar 
signature of the cyclone has degraded, and based on this the hourly 
Tropical Cyclone Updates will be discontinued.

The initial motion is now northward or 360/26.  Helen should turn 
northwestward later today as it starts to interact with a mid- to 
upper-level baroclinic low to its northwest.  After that, the 
cyclone should considerably slow its forward motion and make a 
cyclonic loop as it gets absorbed into the low.  The new forecast 
track follows the general trend of the large-scale dynamical models.

Helene should continue to weaken, and simulated satellite imagery 
suggests it should lose its convection later today, the new 
intensity forecast calls for the cyclone to weaken and become 
post-tropical in about 12 h, followed by transition to an 
extratropical cyclone as it merges with the baroclinic low.  The 
remnant extratropical low is expected to dissipate by 72 h.

Although the system will weaken as it moves over land, the fast
forward speed of Helene during the next 12 hours or so will result
in a far inland penetration of strong winds over parts of the
southeastern United States, particularly over northern Georgia, 
including strong gusts over the higher terrain of the southern 
Appalachians. Accordingly, a higher-than-normal gust factor is 
indicated in the official forecast while Helene is inland.

KEY MESSAGES:

1. The storm surge along portions of the Florida Big Bend coast and 
other portions of the west coast of Florida should subside today.

2. Damaging wind gusts will continue to penetrate well inland over 
portions of Georgia and the Carolinas today, particularly over the 
higher terrain of the southern Appalachians. Residents in these 
areas should be prepared for the possibility of long-duration power
outages.  If you use a generator after the storm, be sure it is
placed outside at least 20 feet away from doors, windows, and
garages to avoid deadly carbon monoxide poisoning.

3. Catastrophic and life-threatening flash and urban flooding, 
including numerous significant landslides, is expected across 
portions of the southern Appalachians through Friday. Considerable 
to locally catastrophic flash and urban flooding is likely for 
northwestern and northern Florida and the Southeast through Friday. 
Widespread significant river flooding is likely, some of which will 
be major to record breaking.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 32.8N  83.0W   60 KT  70 MPH...INLAND
12H  27/1800Z 36.4N  84.5W   35 KT  40 MPH...POST-TROP/INLAND
24H  28/0600Z 36.9N  87.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
36H  28/1800Z 36.7N  87.3W   25 KT  30 MPH...POST-TROP/EXTRATROP
48H  29/0600Z 36.7N  87.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
60H  29/1800Z 36.9N  86.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
72H  30/0600Z...DISSIPATED

$$
Forecaster Beven