476 
FXUS62 KGSP 060546
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
146 AM EDT Mon Sep 6 2021

.SYNOPSIS...
A weak cold will reach the North Carolina mountains tonight, and
will move through the forecast area on Monday, bringing isolated to 
scattered showers to the region. Another cold front is forecast to 
cross our area on Wednesday and could bring some showers and 
thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 145 AM: A broken line of showers ahead of a cold front had 
moved into the NC mountains. Coverage was better west of the French 
Broad Valley while only isolated coverage was seen over the Northern 
Mountains. Expect this trend to continue through the early morning. 
Coverage should increase across NE GA and the western Upstate as 
showers to the west move in there as well. Precip has been on the 
light side and this is expected to continue, although moderate QPF 
is possible in any heavier showers.

Precip chances diminish across the I-40 corridor and northern 
mountains after daybreak as the front drops into the area and drier 
air moves in behind. The front is quite slow moving, so precip 
chances will continue along the front. The highest precip chances 
will be across NE GA and the western Upstate where moisture and 
forcing lingers longer. Precip chances taper off across the NC 
southern Mountains, southern foothill, and Southern Piedmont. 
Guidance shows the best chance of instability will be across NE GA 
and the western Upstate where moisture pools and the subsidence 
inversion erodes enough for weak instability to develop. These 
locations have the best chance to see a thunderstorm. QPF still 
looks to generally be light, but moderate values are possible in 
heavier showers and thunderstorms. Highs will be near or just below 
normal. 

The front pushes south of the area this evening with convection 
quickly tapering off with loss of heating and drier air moving in. 
Should see a return of mountain valley fog, with patchy fog 
elsewhere. Lows will be near or just below normal.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 1:30 PM EDT Sunday: Throughout the short term forecast period, 
a ridge of high pressure will build across the western CONUS while 
periods of troughing dominate across the northeastern CONUS. Towards 
the beginning of the forecast period, a trough stretching from 
southern Canada into the Carolinas will lift northeast and out of 
the United States while a cold front associated with the trough 
stalls southeast of the CWA. The front will be draped across the 
eastern Carolinas Monday night into Tuesday. Flow at the sfc will 
turn southerly Tuesday afternoon allowing PWATs to climb. This front 
combined with increased moisture could lead to a slight chance to 
chance for diurnal showers and thunderstorms, mainly across the 
southwestern CWA Tuesday afternoon into early Tuesday evening.
Another upper-level trough will deepen as it tracks across southern 
Canada and the Great Lakes region Tuesday into Wednesday while an 
area of broad low pressure tries to form in the Gulf of Mexico. This 
trough will drag a second cold front across NE Georgia and the 
western Carolinas Wednesday afternoon into Wednesday evening 
increasing shower and thunderstorm chances again. PWAT values should 
remain elevated as southerly flow remains in place ahead of the 
FROPA. This frontal boundary could interact with the moisture influx 
from the low in the Gulf, but how much of this moisture is able to 
make it into the western Carolinas and NE Georgia remains the main 
question. since more moisture could potentially be associated with 
this second FROPA, have PoPs at chance across the majority of the 
CWA. The cold front is expected to push southeast of the forecast 
area early Thursday morning. Highs throughout the short term will be 
roughly 3 to 8 degrees above climo. Lows are expected to be several 
degrees above climo as well.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 2:00 PM EDT Sunday: The upper-level trough mentioned above 
will continue tracking east out of the Ohio Valley into the 
Northeast US throughout much of the extended before tracking off the 
northeast US coast early Sunday. Meanwhile, the area of low pressure 
in the central Gulf is expected to track east across the eastern 
Gulf Thursday into Friday before tracking across Florida Saturday. 
However, the 00z ECMWF has the low tacking a more northerly track 
into the Deep South and eventually across the Carolinas late 
Saturday into Sunday ultimately leading to wetter and cloudier 
conditions. As the majority of the extended guidance has high 
pressure building in at the sfc across much of the eastern CONUS 
throughout the extended, and in collaboration with neighboring WFOs, 
decided to stick with the drier model solutions for now. High 
temperatures look to remain above climo throughout the extended 
forecast period.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: SHRA and low VFR cigs moving into the 
mountains ahead of a cold front. VFR cigs and isolated SHRA will 
spread across the foothills and Piedmont early this morning. MVFR 
vsby and cigs develop across the mountains as low level moisture 
fills in. The front drops across the area after daybreak turning the 
SW wind to NW. Lingering moisture and instability along the slow 
moving front will keep low VFR cigs and isolated showers for KCLT 
and KGSP/KGMU into the afternoon. Instability and moisture is better 
near KAND, so a PROB30 for TSRA included there. Low clouds scatter 
out behind the front with winds turning briefly SE then back to N 
for the evening.

Outlook: Nocturnal Piedmont restrictions cannot be ruled out late 
tonight with front stalling just south of the region. A few 
SHRA/TSRA may redevelop Tuesday afternoon. A second cold front may 
bring scattered convection Wednesday into Thursday. Mountain valley 
fog and stratus remain possible each morning.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...DEO
NEAR TERM...RWH
SHORT TERM...AP
LONG TERM...AP
AVIATION...RWH