Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
815 PM EDT Mon Aug 30 2021

.SYNOPSIS...
Tropical cyclone Ida will continue to weaken while moving
northeast from Mississippi toward West Virginia on Tuesday and
Wednesday, bringing periods of heavy rain and gusty wind.
Continental high pressure is expected to settle into the region
later in the week with mostly sunny skies and near to slightly below
normal temperatures.

&&

.NEAR TERM /THROUGH TUESDAY/...
600 PM Update...Realigned PoPs a little favoring better chances
across the farther wrn mtn zones over the next few hours. Trop bands
of rain and tstms currently remaining west of the FA, but some
relatively higher wind speeds/gusts may work into the NE GA, so
bumped up wind speeds a bit thru the evening.

As of 240 PM Monday: Upper anticyclone centered just southeast of
the CWA will continue to gradually drift southeast and weaken
through the period, as height falls associated with Hurricane Ida
gather some speed in lifting from the lower Miss Valley into the TN
Valley through the period. Mountains are still the favored location
for any diurnal convection into the evening. Should see a downward
trend in convection this evening before an uptick in precip chances
as the outer bands of Ida move toward the mountains. Do not expect
more than the usual convective QPF or gusty wind potential through
tonight. Can't rule out some mountain valley fog overnight, but
increasing mid and high clouds should limit the chance of any dense
fog. Lows will be above normal.

Precip chances steadily increase Tuesday, especially across the
western forecast area, as the center of Ida moves into Middle TN.
QPF remains on the light to moderate side during the morning with
highest amounts over the NE GA mountains, SC mountains, and NC
mountains west of the French Broad valley. QPF ramps up during the
afternoon with heavy rainfall possible in these same areas and the
upper French Broad Valley. Moderate QPF will be possible along and
near the Blue Ridge escarpment from Polk and Henderson counties
north to Avery and Caldwell counties. Will issue a Flash Flood Watch
for the mountains and bordering foothills where upslope enhanced
precip is expected. As the bands of convection move into the area
from the west, the chance of isolated tornadoes increases as well.
Shear and helicity will be in ample supply across portions of the
area. The low level winds are less backed with more unidirectional
hodographs across portions of the area limiting tornado potential.
MLCAPE could reach moderate levels, so instability doesn't look to
be a limiting factor. Should be a gradient in highs with below
normal west and above normal east.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 225 PM EDT Monday: The short-term forecast picks up at 00z
on Wednesday with the remnant low of TC Ida centered to our west
over central TN/northern AL and tracking NE. Overall, the latest
model guidance is tracking the system a bit farther east compared
to previous fcsts, but still has it centered to our north over
Virginia/Maryland by 00z Thurs. By late Thurs, the low should be
moving off the Atlantic Coast with robust high pressure spreading
over the Southeast in its wake. We still expect precip chances to
peak late Tuesday night and early Wednesday before ramping down
Wed aftn/evening. Accelerating flow east of the low center is still
expected to result in a secondary precip max in the SLY upslope
areas of southwest NC. The latest QPF guidance has trended a bit
lower overall, but not by much. The heaviest rainfall still appears
to be most likely from the higher elevations of the Balsams SW to
the northeast GA mountains, with storm totals of 3 to 5 inches
(with isolated 5+) appearing likely over these areas. Otherwise,
a sharp gradient in QPF is expected away from the escarpment with
much of the fcst area expected to see amounts in the 0.5 to 2 inch
range. The other main concerns will be gusty gradient winds and a
low-end severe threat Tuesday afternoon thru early Wed. Considering
the current strength of Ida and its relatively fast movement inland,
the potential exists for fairly robust winds over the higher terrain.
Lastly, there will be a severe storm/tornado threat as low-lvl shear/
helicity increases Tuesday aftn. The amount of instability/buoyancy
remains difficult to pin down, but could certainly be enough to cause
problems.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 155 PM EDT Monday: The extended forecast picks up at 00z
on Friday with broad upper ridging centered over the Southern
Plains gradually spreading eastward and pushing the upper trof
offshore. The upper ridge then lingers across much of the Central
and SE CONUS thru the weekend, but does get suppressed by another
northern stream upper trof early next week. At the surface, the
remnant low associated with Ida should be moving off the Atlantic/
New England Coast by early Friday as robust Canadian high pressure
spreads farther southward. For the remainder of the period, high
pressure will linger over our region and will weaken/moderate over
the weekend as low-lvl flow weakens and loses its NLY component.
Overall, the period is dry with noticeably lower dewpts and cooler
temps early in the period. Highs will start out about a category
below normal on Friday, and warm to above normal by early next
week.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Starting to see bands of precip/tstms move
into the far wrn mtns attm. Mid and high level cloud cover has
increased and expect these to limit the potential for flight
restrictions across most terminals, except at KAVL where MVFR/IFR
CIGS and VSBY is probable arnd daybreak. Waves of tropicla -shra and
tstms will affect all sites Tue afternoon with low to moderate gusts
continuing into the late period. At KAVL...a llvl jet will lower
enuf for LLWS mention aft 20z and persist thru the period.

Outlook: Periods of rain/restrictions and some gusty winds can be
expected Wednesday as the remnants of Ida move by to our north.
Drying follows for the latter part of the week.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High  99%     High  82%
KAVL       High  95%     Med   65%     High  86%     High  81%
KHKY       High 100%     High  87%     High  97%     High  93%
KGMU       High 100%     High  98%     High 100%     Med   79%
KAND       High 100%     High 100%     High 100%     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...Flash Flood Watch from 8 AM EDT Tuesday through Wednesday
     afternoon for GAZ010-017-018.
NC...Flash Flood Watch from 8 AM EDT Tuesday through Wednesday
     afternoon for NCZ033-048>053-058-059-062>065-501>510.
SC...Flash Flood Watch from 8 AM EDT Tuesday through Wednesday
     afternoon for SCZ001>005.

&&

SYNOPSIS...DEO
NEAR TERM...RWH/SBK
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...SBK

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
650 AM EDT Mon Aug 30 2021

GAZ010-017-018-NCZ033-048>053-058-059-062>065-501-503-505-507-509-
SCZ001>003-311100-
Rabun-Habersham-Stephens-Avery-Madison-Yancey-Mitchell-Swain-Haywood-
Buncombe-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Caldwell Mountains-Burke Mountains-McDowell Mountains-
Rutherford Mountains-Polk Mountains-Oconee Mountains-
Pickens Mountains-Greenville Mountains-
650 AM EDT Mon Aug 30 2021

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

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The remnants of tropical cyclone Ida are forecast to pass from the
Tennessee Valley to the central Appalachians Tuesday into Wednesday.
Periods of heavy rain and gusty southerly winds will develop Tuesday
afternoon into the evening hours and continue into Wednesday.
Flash flooding of urban and small streams as well as minor river
flooding will be possible. Isolated severe thunderstorms with a weak
and brief tornado or two is also possible, mainly Tuesday afternoon
through early Wednesday morning. Interests across the area should
continue to monitor the forecast over the next couple of days as this
situation evolves.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ026-028-029-NCZ035>037-056-057-068>072-082-502-504-506-508-510-
SCZ004>014-019-311100-
Franklin-Hart-Elbert-Alexander-Iredell-Davie-Catawba-Rowan-Cleveland-
Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-Greater Caldwell-
Greater Burke-Eastern McDowell-Greater Rutherford-Eastern Polk-
Greater Oconee-Greater Pickens-Greater Greenville-Spartanburg-
Cherokee-York-Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
650 AM EDT Mon Aug 30 2021

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

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The remnants of tropical cyclone Ida are forecast to pass from the
Tennessee Valley to the central Appalachians Tuesday into Wednesday.
Periods of heavy rain and breezy southerly winds will develop
Tuesday afternoon into the evening hours and continue into Wednesday.
Isolated severe thunderstorms with a weak and brief tornado or two
will be possible, mainly Tuesday afternoon through early Wednesday
morning. Interests across the area should continue to monitor the
forecast over the next couple of days as this situation evolves.

.SPOTTER INFORMATION STATEMENT...

None.

RM

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
651 PM EDT Mon Aug 30 2021

NCZ048-049-302315-
Yancey NC-Madison NC-
651 PM EDT Mon Aug 30 2021

...A strong thunderstorm will impact portions of east central Madison
and west central Yancey Counties through 715 PM EDT...

At 650 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles northeast of Marshall, or near Mars Hill, moving northeast at
10 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Mars Hill, Faust, Swiss and Wolf Ridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3587 8236 3580 8249 3580 8252 3579 8254
      3583 8260 3597 8255 3597 8253
TIME...MOT...LOC 2250Z 220DEG 8KT 3586 8251

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

8

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
740 PM EDT Mon Aug 30 2021

NCZ051-058-310030-
Graham NC-Swain NC-
740 PM EDT Mon Aug 30 2021

...THUNDERSTORMS WITH TORRENTIAL RAINFALL WILL IMPACT WEST CENTRAL
SWAIN AND GRAHAM COUNTIES UNTIL 830 PM EDT...

At 739 PM EDT, Doppler radar indicated thunderstorms with torrential
rainfall along a line extending from 15 miles northwest of
Robbinsville to 7 miles northwest of Andrews, and moving northeast at
15 mph.

Locations to be impacted include... Robbinsville, Santeetlah and
Lake Santeetlah, Fontana Village and Fontana Lake, Smoky Mountains
at Twentymile Creek, Tapoco and Deals Gap.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

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 3537 8401 3541 8402 3546 8396 3547 8392
      3552 8388 3553 8382 3555 8378 3526 8379
      3525 8385 3522 8397 3523 8400 3527 8401
      3529 8403 3531 8402 3531 8404 3535 8404
TIME...MOT...LOC 2339Z 214DEG 12KT 3551 8397 3525 8393

8

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
913 PM EDT Mon Aug 30 2021

GAZ010-017-310145-
Rabun GA-Habersham GA-
913 PM EDT Mon Aug 30 2021

...A strong thunderstorm will impact portions of northwestern
Habersham and western Rabun Counties through 945 PM EDT...

At 913 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Cleveland, or near Helen, moving northeast at 25
mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Clayton, Tiger, Lake Burton, Seed Lake and Batesville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3482 8365 3484 8366 3488 8366 3491 8363
      3492 8360 3494 8360 3495 8355 3488 8338
      3458 8362 3459 8364 3461 8365 3462 8364
      3466 8366 3468 8364 3471 8364 3473 8362
      3476 8363 3480 8368
TIME...MOT...LOC 0113Z 206DEG 23KT 3469 8368

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

8