428 
FXUS62 KGSP 081030
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
630 AM EDT Fri Oct 8 2021

.SYNOPSIS...
Upper level low pressure moves into the Great Lakes today but 
periods of widespread showers and locally heavy rainfall are still 
possible. Moisture lingers over the area Saturday as a surface low 
pressure center moves north along the Carolina Coast. Dry high 
pressure builds in on Sunday and remains in place through next week 
with warming temperatures.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 6:30am EDT Friday:  Light to moderate showers currently over 
the southwest quadrant of the CWA.  These are expected to increase 
in coverage to the north and east through the day.

A negatively-tilted upper trough lies west of the area and will 
finally eject northeastward today.  Surface low with this system 
lies off the coast of South Carolina currently, and will make 
gradual progress northeastward.  This will give fairly steady, 
though light to moderate, easterly to northeasterly surface winds. 
Rainfall is expected to be enhanced in upslope areas of the Southern 
Appalachian, particularly along the escarpment zone adjacent to the 
foothills.  Precipitable water levels at around 1.5", while not 
extreme, are elevated for this time of year, and passage of upper 
system will provide ample upper lift to wring-out moisture. 
Additional rainfall amounts today of 1 to 2 inches are possible in 
some areas today, which will fall on very saturated soils, thus 
continuing the threat of flooding.  Surface CAPE levels are minimal 
early this morning, and showers on radar are quite shallow.  With a 
little warming after daybreak today, sufficient sbCAPE should 
develop to support thunder storms as the main form of rain.  Rain 
and thunder will begin to end from West to East across the region 
this evening as upper system ejects northeastward, and surface winds 
become more northerly.  Rain and clouds will keep temperatures 
moderate, with a muted diurnal range, and with highs only warming 5 
degrees or so above the overnight lows.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 250 AM Friday: A wave rotating around the departing upper low 
will close off into its own upper low off the Carolina coast 
Saturday. This low will slowly open up and move up the East Coast 
Sunday as an upper ridge axis move over our area from the west. This 
feature interacts with an elongated area of surface low pressure off 
the South Carolina coast. The low initially has potential for 
tropical development but interaction with the upper low keeps it 
from fully developing tropical characteristics. Still, the low does 
strengthen and moves slowly toward Cape Hatteras through Saturday 
night, across or near the Cape Sunday then toward the Virgina coast 
Sunday night. A moist easterly flow around the low will bring keep 
low level moisture and weak instability over at least the eastern 
portion of the CWFA Saturday leading to scattered showers and 
isolated thunderstorms. Most of the guidance shows the flow turning 
more northeasterly then northerly Saturday night into Sunday night. 
This will bring drier air and a suppressing subsidence inversion 
into the area. There is some guidance showing lingering low level 
moisture and more easterly flow during this time. A guidance blend 
keeps the area dry, after some lingering showers Saturday evening. 
Therefore, have continued the dry forecast. Highs near normal 
Saturday rise a few degrees above normal on Sunday. Lows remain 
nearly steady around 5 degrees above normal.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 130 AM Friday: Most of next week looks benign, but seasonally
warm, with a positively-tilted upper ridge in place on Monday that
gets reinforced on Wednesday. One system will lift northeastward
across the upper Midwest on Tuesday and some of the model guidance
responds with isolated showers over the mtns, but at this point
the possibility seems too remote to mention. Temps will be on the
order of 5 deg above normal through most of the period...more like
mid September. The pattern will start to become more progressive
late in the week, with the upper ridge axis moving offshore and
a broad upper trof pushing a weak front toward the fcst area from
the west on Friday. That will finally bring a small precip chance
into the western zones for the end of the week.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Rain, low clouds, and reduced visibility will 
continue around the area through Friday, with MVFR to LIFR 
conditions at times. Ceilings of 500FT AGL are currently widespread 
with little improvement expected before 18Z.  Wind direction will be 
fairly steady from the northeast as surface is parked off the South 
Carolina Coast, with speeds of calm to 10kts. Early this morning, 
Convective instability levels are minimal and area of scattered 
showers well to the west of KCLT and I77, are not expected to 
produce any lightning. Showers are expected to spread over most 
areas after day break today, with thunder becoming more likely in 
the afternoon. 

Outlook: Finally, some drier air will try to work in from the west
over the weekend. Conditions will return to prevailing VFR beginning
on Saturday morning. Low-level moisture may linger, keeping a
chance of low cigs and fog, especially late night/early mornings.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch until noon EDT today for GAZ010-017-018-026-
     028-029.
NC...Flash Flood Watch until noon EDT today for NCZ033-049-050-052-
     053-059-062>065-501>510.
SC...Flash Flood Watch until noon EDT today for SCZ001>005-010-011-
     019.

&&

$$
SYNOPSIS...CAC
NEAR TERM...WJM
SHORT TERM...RWH
LONG TERM...PM
AVIATION...WJM