566
FXUS62 KCAE 270136
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
936 PM EDT Thu Sep 26 2024

.SYNOPSIS...
Hurricane Helene is now a major hurricane in the northeastern Gulf
of Mexico, approaching the Florida Panhandle region. Widespread rain
and severe weather will become increasingly likely across the area
tonight. Confidence in impacts is increasing with tropical storm
force winds as the primary threat. A few tornadoes will be possible
through Friday morning along with flash flooding. The storm is
expected to move west and north of the area Friday with diminishing
winds.

&&

.NEAR TERM /TONIGHT THROUGH FRIDAY/...
Key Messages:
- Conditions deteriorate tonight as Hurricane Helene moves north,
  passing to our west tonight.
- Tropical Storm Warning in effect for the entire CWA. Potential
  for gusty winds of 50-60 mph, especially in the CSRA.
- Tornado threat peaking tonight, with a Tornado Watch in effect
  until 8 AM Friday morning.
- Flood Watch in effect through Friday afternoon for the CSRA and
southwestern Midlands. Areas of heavy rainfall could result in flash
flooding, especially south and west of I-26.

This afternoon through Friday Morning:

Hurricane Helene has maximum sustained winds of 140 mph will be
making landfall shortly in the Florida Panhandle. After that, it
will move rapidly moving northward through Western Georgia tonight.
Rain chances will continue to rise again over the next several
hours. The most significant impacts are expected this evening
continuing through the overnight hours. Potential hazards from
Helene include strong wind gusts, isolated tornadoes, heavy
rainfall, and localized flooding.

Wind: A Tropical Storm Warning is in effect for the entire CWA. The
hurricane has an unusually large wind field for a tropical
cyclone in the lower latitudes and will be transitioning to an
extra-tropical cyclone after landfall resulting in a tricky
wind forecast for the Midlands and CSRA. What we can say with
higher confidence is that the strongest winds are likely across
the CSRA and Southwestern Midlands which will be closer to the
cyclone center. There will be a potential for the stronger winds
to cause localized wind damage including isolated to scattered
power outages.

Tornadoes: With Helene forecast to pass to our west, this places the
FA in the right-front quadrant of the cyclone which is a favorable
location for tropical tornadoes. The combination of strong 0-6
km wind shear and increasing helicity will support tornado
development in any thunderstorms that develop. The greatest risk
will come tonight in rainbands associated with Helene. It is
important to note that many, but not all, tropical tornadoes
develop quickly and are short lived resulting in limited lead
time. This threat is compounded by the timing of greatest risk
which is during the overnight hours.

Heavy Rainfall and Flash Flooding: Rainfall chances basically
categorical or close to if not 100 percent overnight into Friday
morning.  A Flood Watch is in effect through Friday afternoon for
portions of the forecast area. Rainfall amounts are likely to be
highest closest to the track. Forecast rainfall amounts vary greatly
from east to west with the potential for 2"-5" inches of rainfall
with locally higher amounts in the watch area.

Outside of the tropical hazards, small diurnal drop off overnight
with lows expected to fall into the low to middle 70s.

Friday late morning through Friday afternoon:
The remains of Helene will rapidly track off to the northwest of
the area, towards central TN and KY through the day. Rainfall
will be ending towards noon time, and conditions will improve
through the afternoon. Afternoon highs will moderate somewhat
with the return of some sunshine.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Key messages:
- A closed upper low over the Ohio River Valley this weekend
  with a chance of showers mainly north of I-20.
- River Flooding expected to be occurring.

A closed upper level low pressure system over the Ohio River Valley
absorbs TC Helene Friday Night and then crawls eastward toward the
Mid Atlantic States this weekend. The best chance for showers
appears to be on Sunday with the upper low directly to the north of
the Carolinas. Temperatures are expected to be slightly above normal
for the end of September.

The excessive amount of rainfall which will continue to fall in
Upstate SC during the passage of TC Helene is expected to increase
river flows to minor to moderate flood stage this weekend.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Key Messages:
- Drier and continued warm conditions expected next week.

A pesky closed upper level low pressure system moves offshore and
begins to open up on Monday and is gradually replaced by above normal
H5 heights. This should result in dry weather and temperatures
3 to 5 degrees above climatology for early October. Some river
levels should drop below flood stage by mid week.

&&

.AVIATION /01Z THURSDAY THROUGH TUESDAY/...
Restrictions expected to continue at the terminals tonight through
daybreak Friday morning. Conditions gradually improve Friday
afternoon.

After a brief break, showers with embedded thunderstorms will move
back into the area from the south. As such, a majority of the
terminals will have MVFR/IFR restrictions into Friday morning.
Conditions then improve late Friday morning into Friday afternoon,
with VFR returning by Friday evening.

East to southeast winds will begin to increase over the next few
hours as Helene approaches. Sustained speeds may increase to 35-45
kts and gusts of 50-60 kts at times, particularly at AGS/DNL. Strong
winds will also be present aloft. As Helene passes to the west,
winds veer to the south, then southwest by daybreak Friday with
speeds decreasing through the afternoon.

EXTENDED AVIATION OUTLOOK...Restrictions ease Friday evening into
the weekend.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Flood Watch through Friday afternoon for SCZ016-018-020>022-
     025>028-030-035-037-041-115-116-135-136.
     Tropical Storm Warning for SCZ016-018-020>022-025>031-035-037-
     038-041-115-116-135>137.
GA...Flood Watch through Friday afternoon for GAZ040-063>065-077.
     Tropical Storm Warning for GAZ040-063>065-077.
&&

$$