Flash Flood in South Carolina, October 8, 2021

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
702 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 /11Z 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 low is parked off the
South Carolina Coast, with speeds of calm to 10kts. This morning,
Convective instability levels are minimal and area of scattered
showers south and west of KGSP, are not expected to produce any
lightning until later this morning. Showers are expected to spread
over most areas after day break today, with thunder becoming more
likely in the afternoon. Upper system moves out Friday night, with
clearing and improving conditions from west to east by Saturday
morning.

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

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
438 AM EDT Fri Oct 8 2021

GAZ010-017-018-026-028-029-NCZ033-049-050-052-053-059-062>065-
501>510-SCZ001>005-010-011-019-090845-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Yancey-Mitchell-
Haywood-Buncombe-Northern Jackson-Macon-Southern Jackson-
Transylvania-Henderson-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Greater Rutherford-Polk Mountains-Eastern Polk-
Oconee Mountains-Pickens Mountains-Greenville Mountains-
Greater Oconee-Greater Pickens-Anderson-Abbeville-Greenwood-
438 AM EDT Fri Oct 8 2021

...FLASH FLOOD WATCH IN EFFECT UNTIL NOON EDT TODAY...

This Hazardous Weather Outlook is for northeast Georgia, western
North Carolina and upstate South Carolina.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ035>037-048-051-056>058-068>072-082-SCZ006>009-012>014-090845-
Alexander-Iredell-Davie-Madison-Swain-Catawba-Rowan-Graham-Cleveland-
Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-Greater Greenville-
Spartanburg-Cherokee-York-Laurens-Union SC-Chester-
438 AM EDT Fri Oct 8 2021

This Hazardous Weather Outlook is for piedmont North Carolina,
western North Carolina and upstate South Carolina.

.DAY ONE...Today and tonight.

Numerous to widespread showers along with isolated thunderstorms
are expected off and on today, especially this morning. The main
threat will be from locally heavy rainfall. Isolated flash flooding
could develop in areas that see multiple rounds of heavy rainfall.
Locations that have received heavy rainfall in previous days will be
most susceptible to developing flash flooding. Occasional cloud-to-
ground lightning will also be possible with any thunderstorms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.