Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1049 AM EST Fri Jan 1 2021

.SYNOPSIS...
Moisture increasing ahead of an approaching cold front will result
in heavy rain showers at times through Friday. Brief drying and very
warm conditions are expected behind the departing front on Saturday,
but with coastal low pressure along the stalling front likely
bringing another round of rain to the region Saturday night. Drier
high pressure will return for the early and middle part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 10:25 AM EST Friday: Widespread light to moderate showers
continue to move over the area from the south, with heavier precip
expected this afternoon as front makes its way thru the CWFA. Winds
have picked-up some from the NE which will help keep the wedge in
place. Temps have changed little due to cool NELY sfc flow, clouds,
and rain.

Otherwise, the latest guidance on storm total rain from now thru
Saturday morning is still one to two inches, with the heaviest
amounts in the western foothills from NE GA to Hendersonville. Rain
is courtesy of a strong synoptic storm system with moisture
advection ahead of a major cold front that reaches the central CWA
by midnight tonight and exits eastward by daybreak Saturday.
Moisture advection is above the surface wedge of cool air due to
entrenched cold-air damming.  Cool surface air should prevent much
in the way of severe thunderstorms with passage of this system.
Current northeasterly surface winds are weak, but stable wedge looks
to remain until passage of the cold front after dark this evening.
Enough elevated CAPE is seen in model soundings to be worth at least
a mention of isolated thunder for piedmont areas. Clouds, NELY sfc
winds, and rain will keep a lid on temperatures today with a limited
diurnal range of perhaps 5 degrees.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM EST Friday: The frontal zone that is impacting our
region during the near-term should make a full fropa or exist along
the eastern fringe of the cwa by 12Z Saturday. Some residual
moisture could still produce some light activity along the I-77
Corridor, but will quickly fade by lunchtime. Model guidance has the
frontal boundary stalled around the coastal plain. Expect the wedge
to quickly erode due to the post-frontal environment which will
allow for a good amount of insolation over the cwa. Thus,
temperatures will push well into the 60s for highs Saturday. A
secondary upper low will slide over the Mid MS Valley during the day
Saturday as it approaches the OH Valley Saturday night into early
Sunday. With the area on the eastern side of the trough and a weak
sfc low riding along the stalled boundary to the south and east,
expect another round of precip to move into most locations with
possible heavy QPF amounts along the far eastern and southern zones.
The upper forcing will become greatest between 00Z Sunday through
09Z Sunday, but the ECMWF has the activity lingering slightly longer
than the GFS. Most of anything that is left with this system will
move out by 18Z Sunday at the latest as the upper forcing lifts to
the north and east. A brief period of snow showers can't be ruled
out over the NC mountains near or along the TN Border with low-level
moisture and CAA setting up shop on the backside of the system with
west to northwesterly flow expected Sunday and Sunday night. Sfc
high begins to extend over the cwa by the end of the forecast
period, but a quick moving clipper system is shown moving through
the area Sunday night into Monday, but should only promote enhanced
cloud cover over the higher elevations due to the lack of moisture
associated with it. A snow shower at best could eek out at the
highest peaks, but little to no accumulation is expected.
Temperatures will remain above normal for much of the short-term
across the entire cwa.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 330 AM EST Friday: The aforementioned clipper system will
quickly move out of the area by Monday with gradual height rises
expected during the day from the west. Deep upper ridging will
begin to control the overall weather pattern for the middle
part of the week as a sfc high sets up shop along the Eastern
Seaboard. Expect a return flow by the latter part of the new
work week as the sfc high begins to push offshore, ahead of the
next system. Model guidance are hinting at a digging upper low
to slide into the region Thursday into Friday from the Midwest
with an associated frontal boundary. This will be the next best
chance for rain as low-level moisture advection works into the cwa
from the south. The ECMWF and GFS are in agreement with the upper
pattern, but differ on the position of the frontal boundary and sfc
low. Both models produce some form of a coastal low Friday morning
that could fetch additional moisture into the region by the very
end of the forecast period. A lull in activity is evident for the
first half of the week, but could become active once again by the
second half based on model trends. Temperatures are expected to
remain above normal for much of the medium range with PoPs making
a return into the forecast by next Thursday and Friday.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere:  Visibility most places has improved as light
rain becomes more prevalent, though VLIFR conditions may continue to
occur temporarily.  Period of heavier rain is indicated in the TAFs
for the timing of a cold front crossing the region. CIGs and VSBY
may not change a whole lot during the day as cold-air-damming
conditions maintain northeasterly winds with deep cloudy air. Once
the front goes by late tonight to early tomorrow morning, winds will
become southweseterly and both CIGs and VSBY will begin to improve.

Outlook: VFR conds will return Saturday into early next week,
although a quick moving system could bring a shot of rain with
flight restrictions Saturday night into early Sunday.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High  80%     High  88%     Med   76%     Med   74%
KGSP       High  91%     Med   78%     Med   68%     Med   74%
KAVL       Med   73%     High  96%     Med   78%     High  88%
KHKY       High  83%     Med   76%     Med   71%     Med   72%
KGMU       High  90%     High  81%     Med   73%     Med   74%
KAND       High  90%     High  91%     Med   73%     High  81%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

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

&&

SYNOPSIS...HG
NEAR TERM...JPT/WJM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...JPT/WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
657 AM EST Fri Jan 1 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-021200-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-
Rowan-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
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-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
657 AM EST Fri Jan 1 2021

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

.DAY ONE...Today and tonight.

Heavy rainfall is expected across the western Carolinas and
northeast Georgia today. Localized flooding of streams and poor
drainage areas is possible, especially along the south-facing slopes
of the extreme southern Appalachians. Minor flooding of main stem
rivers also cannot be ruled out, especially the headwaters area of
the French Broad River.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
102 PM EST Fri Jan 1 2021

GAZ026-028-029-NCZ065-508>510-SCZ002>008-010>012-011915-
Elbert GA-Hart GA-Franklin GA-Eastern Polk NC-Greater Rutherford NC-
Henderson NC-Polk Mountains NC-Greater Pickens SC-Cherokee SC-
Greater Oconee SC-Laurens SC-Abbeville SC-Pickens Mountains SC-
Anderson SC-Greenville Mountains SC-Spartanburg SC-
Greater Greenville SC-
102 PM EST Fri Jan 1 2021

...AN AREA OF HEAVY RAIN WITH EMBEDDED THUNDERSTORMS WILL IMPACT
HART...SOUTHEASTERN FRANKLIN... ELBERT...SOUTHEASTERN
RUTHERFORD...SOUTHEASTERN HENDERSON...POLK... NORTHWESTERN
LAURENS...EASTERN PICKENS...SOUTHEASTERN OCONEE...
GREENVILLE...NORTHWESTERN SPARTANBURG...ANDERSON...NORTHWESTERN
CHEROKEE AND CENTRAL ABBEVILLE COUNTIES UNTIL 215 PM EST...

At 100 PM EST, Doppler radar indicated the leading edge of an area
of heavy rain with embedded thunderstorms along a line extending
from 7 miles southwest of Columbus to 6 miles southwest of
Danielsville, and moving northeast at 30 mph.

Locations to be impacted include...
Greenville Downtown, Anderson, Easley, Clemson, Elberton, Hartwell,
Columbus, Spartanburg, Greenville Eastside and West Greenville.

Very heavy rainfall rates of 1 to 2 inches per hour will be possible
in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

&&

LAT...LON 3401 8294 3403 8294 3404 8298 3410 8304
      3411 8303 3415 8306 3417 8310 3423 8308
      3427 8311 3424 8317 3424 8319 3531 8234
      3528 8174 3514 8179 3402 8263 3400 8289
TIME...MOT...LOC 1800Z 247DEG 31KT 3518 8231 3405 8329

KRENTZ