992
FXUS62 KGSP 261751
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
151 PM EDT Thu Sep 26 2024

.SYNOPSIS...
Tropical Cyclone Helene is forecast to make landfall over the
Florida Panhandle early tonight. The remnant circulation will move
quickly north through Georgia bringing continued heavy rainfall,
significant flooding and strong winds tonight into Friday morning.
Expect a calmer weekend with temperatures near seasonal normals.

&&

.NEAR TERM /THROUGH FRIDAY/...
1000 AM Update...Rainfall rates have lessened as expected across
most areas, while dangerous flooding conditions continue over many
mtn locales. This general lull in activity will continue over the
couple hrs before more moderate rainfall moves back in from the
south and continues into the evening along an elongated sfc trof.
This rain will exacerbate already saturated soils and lead to new
areas of flooding. Low level helicity and deep shear remains quite
high and a few brief tornadoes will be possible...mainly along a
bndry located around the I-77 corridor, but other locales to the
west will be under the gun for tor development into the afternoon.
The latest model trends with Hurricane Helene indicate winds will
likely be stronger as outer bands begin moving across the area late
evening thru the overnight. Will uptick and begin messaging 80 mph
winds across the higher mtn ridges within the Tropical Storm Warning
thru daybreak Fri.

Otherwise, no changes were made to the Tropical Storm Warning or the
Flood Watch with this fcst update. The latest CAMs are still
suggesting that a swath of stronger wind gusts will spread over our
area just after 00z Friday and continue thru the morning. They
should start weakening by the afternoon, but conditions will remain
gusty thru the evening. Otherwise, all signs point to a significant
tropical event across the western Carolinas and northeast Georgia.
Helene will be a large and fast-moving storm, so any additional
minor shifts in the storm track probably won`t change much at this
point. We still expect a rare and significant amount of rainfall
over much of our mountains and adjacent zones with damaging to
catastrophic flooding likely. In the past, once the rainfall gets
above roughly ten inches, we have seen numerous reports of land-
slides across the high terrain. If you live in these areas, it is
imperative that you take whatever precautions you can now, as the
flood/landslide threat will continue to increase today and tonight.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 245 am EDT Wednesday: Calm weather will return to the CWA by
Friday night, as the center of Helen will be spinning down over the
western Ohio Valley...with only some spotty showers expected to
linger across the mountains. Winds will remain gusty Fri evening...
albeit well below any Wind Advisory criteria...but will gradually
diminish through the night. With upper low remaining virtually
stationary across the TN/OH Valley, spokes of vorticity lifting
south of the low will approach the southern Appalachians Saturday
into Saturday night. This is expected to induce scattered shower
development...with perhaps a thunderstorm or two...mainly Saturday
afternoon/evening. Can`t rule out some locally heavy rainfall within
any of this activity, but any precipitation should mostly be light.
Temperatures will be right around normal through the period.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 am EDT Thursday: Global model guidance is not in the
greatest agreement regarding the details of the evolution in the
upper pattern. However, as a strong short wave trough dips into the
northern Great Plains, the general idea is that the upper low...
centered somewhere over the Ohio Valley at the start of the
extended...will begin to wobble across the Mid-Atlantic and evolve
into an open wave at some point early next week. Scattered, mainly
diurnal convection (primarily showers) will be possible across the
forecast area each day from Sunday through Tuesday...with chances
becoming increasingly confined to the mountains later in the period,
as the pattern transitions to more of a NW flow regime in the wake
of the departing trough. Although precip chances are in the
forecast for much of the period, any rainfall is expected to be
light. Temperatures are forecast to be very close to climo through
the period.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Low CIGS and VSBY, into IFR or lower, will
persist this evening through the overnight across all TAF sites. A
sfc trof has become a focusing zone for continued widespread precip
over the area, while thunder chances remain low due to limited
instability. Expect heavy rain overnight as bands associated with
Hurricane Helene traverse the area. Winds will also become more
gusty into the high range while very strong winds off the surface
create sigfnt LLWS aft 09z or thru mid/late morning. Wind directions
will generally remain e/ly to se/ly with KCLT veering sw/ly by the
late period.

Outlook: The remnants of TC Helene and lingering low flight cats
will move north of the area Friday afternoon into Saturday. Isolated
to sct mainly diurnal convection will be possible thru the weekend.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flood Watch through Friday afternoon for GAZ010-017-018-026-
     028-029.
     Tropical Storm Warning for GAZ010-017-018-026-028-029.
NC...Flood Watch through Friday afternoon for NCZ033-035>037-
     048>053-056>059-062>065-068>072-082-501>510.
     Tropical Storm Warning for NCZ033-048>053-056-058-059-062>065-
     068>071-082-501>510.
     Wind Advisory from 8 PM this evening to 2 PM EDT Friday for
     NCZ035>037-057-072.
SC...Flood Watch through Friday afternoon for SCZ008>014-019-
     101>109.
     Tropical Storm Warning for SCZ008>014-019-101>109.
&&

$$

SYNOPSIS...JDL
NEAR TERM...JPT/SBK
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...SBK