899
FXUS62 KGSP 302201
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
601 PM EDT Sun Jun 30 2024

.SYNOPSIS...
Hot and humid conditions today, as well as showers and
thunderstorms ahead of a robust cold front.  Drier and cooler
conditions settle in behind the front Monday and Tuesday, before the
summer heat returns Wednesday and beyond.

&&

.NEAR TERM /THROUGH MONDAY/...
600 PM Update...Pre-frontal convec activity persists across the FA
and has become outflow driven. A multicell line developing northwest
of KCLT will come together over the next hour and push south across
the city of Charlotte. The overall strength of this line will remain
rather strong and an SPS or even a SVR may be needed. The biggest
threat will be damaging downburst winds as the main cell has a
history of downing trees across Morganton. Heavy rainfall will also
accompany these storms and localized urban flooding may become an
issue.

As of 200 PM Sunday...Seeing a few obs with heat indices at or above
105, but convection should start to bring those down. Scattered
convection has developed along a pre-frontal trough roughly parallel
to the NC/SC border and drifting southeast. Meanwhile, the actual
sfc front is still back over the Cumberland Plateau and eastern
KY. There is about 3000 J/kg of sbCAPE south of the pre-frontal
trough, while debris cloudiness is limiting CAPE somewhat to the
north across eastern TN and much of western NC. So decent convection
with a few strong storms should continue to affect the Upstate and
NE GA, while we may need to wait until late aftn or early evening
for activity to really ramp up across the NC mountains. The latest
CAMs are not too excited about the activity coming in from the NW
this evening, and generally dissipate it before reaching the eastern
Escarpment. This is not exactly how the PoP/Thunder grids are
currently, so an update may be needed if these trends hold. Still
may see a few damaging wind gusts with whatever storms do develop
and maximize the CAPE. But shear looks too weak to really get
updrafts organized. A fair amount of clouds will linger overnight,
and the front should usher in some drier air that will limit fog
potential. Lows will remain a few degrees above normal.

Monday looks much quieter, with a return to seasonable temps
and humidity. The cold front will push well south of the area,
while a fairly dry and mild 1028 mb high will nose down from the
Great Lakes. There will probably be enough lingering moisture in
the Upper Savannah Valley and Lakelands for isolated convection,
mainly showers in the aftn. But otherwise, just some fair wx
cu. Highs mainly in the mid 80s to around 90 in the mountain
valleys and Piedmont.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 150 PM Sunday: Not too much change in the short term.
Synoptically, high pressure builds in from the west with an
amplifying high over the southern CONUS. To the north, a dissipating
trough turns flow aloft NW, on Tuesday, but turns more westerly as
the upper high moves over the area. High pressure at the sfc will
slide toward the NE of the CWA by Wednesday, maintaining a stream of
drier and somewhat cooler air for the short term. Modeled upper air
guidance shows a stout subsidence aloft with a mid-level inversion
at the top of the BL, reducing rain chances Tuesday and Wednesday
afternoon. Despite a few slight chance PoPs (15%-30%) mainly
concentrated over the NC mtns, there is almost no QPF response.
Another concern is the wide dewpoint depression at the surface and
at the top of the BL. With very dry air aloft, this could mix down
toward the surface, dropping RH values lower than model guidance
suggests. This would present more issues in terms of fire concerns.
Fuel moisture is dry, especially east of the mountains meaning
vegetation is more prone to ignition. Will continue to monitor.
Otherwise, temperatures look to be closer to climo and begin an
upward trend into the next period.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 200 PM Sunday: The summertime pattern continues into the
extended. Wednesday night and into the extended period. The strong
area of high pressure continues to grow over the southeast and Mid-
Atlantic regions. Persistent height rises over the region will
create temperatures well above normal through the weekend. Guidance
from the GFS and EURO depicts moisture returning toward the end of
the week as the sfc high to the north slides off shore and winds
become more southerly. The advection of moisture does look to keep
dewpoints in the low to mid 70s by end of week. This will have a
direct impact on heat indices, especially those locations east of
the mountains. 100 plus values are possible by Thursday and into the
weekend for areas south of I-85 and eastern NC Piedmont. Will
continue to monitor, but confidence is increasing given the
persistent high pressure settling over the area. Once the high
pressure moves offshore, a return to more diurnally driven
convection is possible across the mountains, though confidence is
low. QPF response still remains low as well. As for fire concerns,
guidance does keep a stout amount of dry air aloft with a a well
mixed boundary layer. Once again, RH values have the potential to be
lower than guidance is depicting should the drier air mix down. Will
continue to monitor.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Scattered convection has developed roughly
near the NC/SC border areas and is drifting SE. The evolution
of convection for the rest of the aftn and evening is really
uncertain, as model guidance is not in good agreement. Have gone
with tempo for TS at all TAF sites during the peak heating hours,
but additional round of mainly scattered SHRA and isolated TS may
enter from the NW this evening. But most of the latest guidance
struggles to carry this activity across the mountains. Thus, have
backed off TS mention for this evening. VFR conditions expected,
except around convection, where heavy precip could take sites
to IFR. Winds also remain light and rather variable until a cold
front pushes in from the north and shifts the winds out of the NW,
then NE by daybreak Monday. Drier air will filter in and should
limit low cig and fog potential, with KAVL having the best chance
of some restrictions early Monday morning.

Outlook: The cold front will push thru and stall just south of
the area, resulting in quieter weather for Monday thru mid-week. A
return of more typical mid-summer diurnal convection is expected
Thursday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ018-026-028-
     029.
NC...Heat Advisory until 8 PM EDT this evening for NCZ070>072-082.
SC...Heat Advisory until 8 PM EDT this evening for SCZ008>014-019-
     104>109.

&&

$$

SYNOPSIS...CP
NEAR TERM...ARK/SBK
SHORT TERM...CP
LONG TERM...CP
AVIATION...ARK