Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1032 PM EDT Wed Aug 1 2018

.SYNOPSIS...
A broad area of low pressure will persist across the Tennessee
Valley through at least Friday. This low will transport deep moisture from
the Gulf of Mexico and produce abundant cloud cover and continued
rounds of precipitation, which will hold high temperatures below
normal.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 1030 PM EDT Wednesday: Strong thunderstorms with occasionally
heavy rainfall continue to redevelop and move across the Piedmont
this evening, while more general light to moderate showers continue
elsewhere. Sill can't rule out an additional severe storm early,
mainly along and south of I-85 and along and east of I-77, but
chances will diminish overnight. The heaviest rainfall will remain
along and south of I-85 and along and east of I-77 as well. These
locations have the best chances for additional advisory level
flooding and possibly flash flooding. The rest of the CWFA will see
additional light to moderate rainfall and will see slower rises on
creeks and streams. This could lead to additional advisory level
flooding.

Otherwise, the latest model guidance, thankfully, continues to play
along with our ongoing forecast with no surprises. The upper level
pattern remains locked in place with a trof axis over the MS River
valley and a large anticyclone over the wrn Atlantic. The pattern
will continue to focus a plume of deep tropical moisture from the
Gulf of Mexico to the srn Appalachians and western Carolinas thru
the near term period. Precipitable water should remain at or above
the upper end of the PW climatology (i.e. well above normal), while
the atmosphere will be characterized by a deep warm cloud layer, and
our meso-beta element vectors remain small. All this is to say that
we have many of the necessary ingredients for flash flooding, so the
ongoing Flash Flood Watch remains in good shape. Precip prob will
remain likely to categorical into the evening while we work thru the
diurnal cycle. There may be something of a relative lull late
tonight/early Thursday morning, but the lull might be more of a
dropoff in intensity, not coverage. We ramp back up after daybreak
on Thursday as we continue to bring mid-level PVA across the region,
add some daytime heating, and bring some increased upper divergence
to bear. That should increase our flood threat thru the day, perhaps
higher than today as we continue to pile up the rain and soak the
ground. As for severe thunderstorms, we cannot rule them out once
again over the eastern fringe of the fcst area in the afternoon as
we once again destabilize to 1500 J/kg of sfc-based CAPE and retain
seasonally strong wind shear. Temps should be on the cool side of
normal where clouds and extensive precip linger.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 245 PM EDT Wednesday: At the start of the forecast cycle our
area (FA) still sits in a blocking pattern. Once again the key
players: the upper level ridge in the west, troffing from the Great
Lakes to the Gulf of Mexico, and the western Atlantic high pressure
system.

The "wave train" continues Thursday night with embedded pockets of
energy shifting through the region in a southwesterly flow aloft.
The right entrance region of the upper level jet continues to show
its hand allowing lifting mechanisms to continue.

It looks like we have to wait for this upper level low in the
Bahamas to rotate around the western periphery of the Atlantic high
pressure system. Once this happens the upper level high will shift
slowly west, and the upper level trough will deamplify considerably.

Meanwhile, precipitable water values remain elevated Thursday night,
at 2.0 inches or greater in spots. Various mechanisms of forcing
will allow for the potential of additional heavy rain. As a result
we will keep high POPS going Thursday night.

For Friday we kept POPS elevated with lingering precipitable waters
still high, and the last vestiges of the upper trough lifts out. At
this point hard to pin point whether any one area would need an
extension of the Flash Flood Watch at this time. The mountains could
be candidates, but not enough evidence at this point

As we start the weekend, although heights will be on the rise,
diurnal showers and thunderstorms should erupt. The higher
elevations look to have the better involvement, but other areas are
still possible.

Once again we kept temperatures in range with the suite of guide,
with less diurnal range than usual.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 155 PM Wed:  The Bermuda High will exert more of an influence
on our weather during the weekend with a good southerly flow of air
into our region. From late Saturday to late Sunday the center of the
Bermuda High gets closer to the Carolina coast. As a result, the
weak 5 to 10 kt southerly 925mb flow becomes even lighter on Sunday
and shifts more toward the west to start the week. Less moisture
transport through time. Precipitable water levels drop from 1.8 in
the lower Piedmont Saturday evening to 1.5 to 1.6 across the area on
Monday. Instability  around 2000 CAPE in piedmont Saturday evening
then 2000 to 2500 late Sunday along the I-85 corridor. The next
trough crosses the Upper Mississippi Valley Monday and Monday night
with the cold front having a roughly 200 mile wide area of frontal
convection.  Height falls across our region in mid week as the
trough becomes established over the Eastern Half of the nation.
Frontal convection expected over our region on Wednesday with the
greater cloud cover.Temperatures will be near normal

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
At KCLT and Elsewhere: Quite a bit of convection around with
everything from VFR to IFR across the area. Expect restrictions
mainly with convection early this evening then deteriorating
conditions through the night with prevailing MVFR becoming IFR.
Mainly cigs at most locations but IFR vsby possible, especially at
KHKY, KAVL, and KAND. TSRA will be most likely at KCLT and KAND this
evening. Can't completely rule them out elsewhere, but chance too
low to include for now. SHRA continue overnight. Conditions only
slowly improve to MVFR by afternoon. SHRA continue through the day
with TSRA possible but most likely during the afternoon. Winds will
be light outside of convection this evening. Direction will be
mainly southerly but will take on an easterly component overnight at
the SC sites and KHKY. Winds return to S to SW during the day
Thursday.

Outlook: A wet pattern will remain in place over the region
through late week. Numerous SHRA/TSRA will develop across the
area, especially each afternoon and evening, along with associated
restrictions. Limited drying may occur over the weekend.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High  95%     High  86%     High  89%     High 100%
KGSP       High  90%     High  80%     Med   73%     Med   78%
KAVL       High  87%     High  90%     High  87%     High  98%
KHKY       High  90%     High  92%     Med   63%     Med   75%
KGMU       High  92%     High  83%     Med   70%     Med   78%
KAND       Med   70%     High  80%     High  94%     Med   75%

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

www.weather.gov/gsp/aviation

&&

.HYDROLOGY...
The current hydrology situation this afternoon is comprised of
two primary areas of concern.  The first is over the far western
mountains including Graham, Haywood, Jackson, Macon, Rabun, and
Swain counties, where instability is poor (SBCAPE <500 J/kg) but low-
level covergence closer to the proximity of the surface front and
overall upslope flow suggest some forcing exists.  This combined
with high PWs of 1.7-1.9" suggest efficient, warm-layer rain
processes are still in play. However, at this time, rainfall rates
are generally less than 1"/hr in the SW mountains; therefore, the
flash flood threat here is not imminent but antecedent conditions
are priming if higher rainfall rates materialize later today into
tonight.

The second area of concern is along and east of the Blue Ridge
Escarpment into the Foothills and Piedmont of the Carolinas and NE
GA where instability is greater (SBCAPE >1500 J/kg) and PW values
are still near or above climatological maxes (1.8-2.1"). Also, Flash
Flood Guidance values are low, especially along the Escarpment, due
to previous activity (<2"/hr). Therefore, the concern for localized
flash flooding is greater in this area as ongoing activity is
producing rainfall rates of 1-3"/hr and some brief anchoring has
been occurring, producing 1-2" of rainfall in as little as 30-45
minutes.  Over urbanized areas, this will produce quick
street/parking lot/underpass flooding and will need to be closely
monitored.

As rainfall continues area wide, antecedent conditions will continue
to deteriorate as we approach the best chances for heavy rainfall
tonight into Thursday.  Therefore, the flood risk will continue to
increase into Thursday before tapering off (but not disappearing
completely) into Friday and the weekend. Meanwhile, as basin-average
rainfall amounts increase into tomorrow, mainstem river flooding
becomes a greater possibility, especially in the climatologically
favorable areas of the upper French Broad River, but rapid response
along the lower Tuckasegee, Swannanoa, South Fork Catawba, and
Pigeon River basins is also possible. At this time, Minor flooding
(i.e., flooding of low-lying areas, greenways, boat-access ramps,
recreational areas) is the primary concern.  As always, monitor the
latest forecasts and stream levels at:

https:/water.weather.gov/ahps2/index.php?wfo=gsp.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch through Friday morning for GAZ010-017-018-
     026-028-029.
NC...Flash Flood Watch through Friday morning for NCZ033-035>037-
     048>053-056>059-062>065-068>072-082-501>510.
SC...Flash Flood Watch through Friday morning for SCZ001>014-019.

&&

SYNOPSIS...DEO
NEAR TERM...PM/RWH
SHORT TERM...TS
LONG TERM...DEO
AVIATION...RWH
HYDROLOGY...

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
553 PM EDT Wed Aug 1 2018

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-
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-Chester-Greenwood-
553 PM EDT Wed Aug 1 2018

...FLASH FLOOD WATCH IN EFFECT THROUGH FRIDAY MORNING...

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

.DAY ONE...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.

Additionally, scattered thunderstorms will be capable of dangerous
cloud-to-ground lightning. A few storms could producing damaging wind
gusts, primarily in the evening.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

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

   Flash Flood Watch.

Even following the end of the Flash Flood Watch, conditions will
remain favorable for localized heavy rainfall each afternoon into
Sunday. Meanwhile, the thunderstorms will be capable of dangerous
cloud to ground lightning.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of hail, damaging
winds, or flash flooding to our office.

ACS

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
901 PM EDT WED AUG 1 2018

NCZ037-057-072-020130-
Rowan NC-Davie NC-Cabarrus NC-
901 PM EDT WED AUG 1 2018

...STRONG THUNDERSTORMS WILL IMPACT CABARRUS...SOUTHWESTERN DAVIE AND
ROWAN COUNTIES UNTIL 930 PM EDT...

At 901 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 6 miles northwest of Kannapolis to 3 miles
southeast of Downtown Concord to 13 miles north of Monroe, and moving
northeast at 30 mph.

Locations to be impacted include...
Kannapolis, Downtown Concord, Salisbury, China Grove, Spencer,
Landis, Enochville, Granite Quarry, Rockwell and Mt Pleasant.

Wind gusts up to 40 mph and 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.

&&

LAT...LON 3550 8030 3519 8051 3523 8058 3532 8057
      3551 8074 3562 8076 3585 8069 3582 8047
      3579 8048 3577 8045 3574 8046 3572 8038
      3572 8034 3571 8032 3568 8033 3559 8021
      3555 8021 3552 8018 3550 8018
TIME...MOT...LOC 0101Z 207DEG 27KT 3556 8070 3538 8054 3519 8056

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
916 PM EDT WED AUG 1 2018

GAZ029-SCZ011-020200-
Elbert GA-Abbeville SC-
916 PM EDT WED AUG 1 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN ELBERT AND
SOUTHWESTERN ABBEVILLE COUNTIES UNTIL 1000 PM EDT...

At 915 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles southeast of Elberton, or 4 miles east of Nancy Hart State
Park, moving northeast at 20 mph.

Locations to be impacted include...
Calhoun Falls, Lowndesville, Nancy Hart State Park, Bobby Brown State
Park, Lake Strom Thurmond, Lake Russell, Rice Town and Fortsonia.

Wind gusts up to 40 mph and 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.

&&

LAT...LON 3398 8261 3397 8264 3399 8265 3398 8273
      3397 8278 3398 8279 3424 8264 3409 8237
      3406 8241 3406 8245 3408 8248 3407 8250
      3407 8253 3401 8260 3399 8258 3396 8257
TIME...MOT...LOC 0115Z 213DEG 18KT 3397 8267

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
932 PM EDT WED AUG 1 2018

GAZ018-026-028-029-020215-
Elbert GA-Hart GA-Franklin GA-Stephens GA-
932 PM EDT WED AUG 1 2018

...STRONG THUNDERSTORMS WILL IMPACT FRANKLIN...SOUTHEASTERN
STEPHENS...NORTHWESTERN ELBERT AND WESTERN HART COUNTIES UNTIL 1015
PM EDT...

At 932 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 6 miles southwest of Carnesville to 6 miles
northwest of Danielsville to 6 miles east of Athens, and moving
northeast at 15 mph.

Locations to be impacted include...
Carnesville, Royston, Lavonia, Gumlog, Bowman, Canon, Franklin
Springs, Bowersville, Martin and Avalon.

Wind gusts up to 40 mph and 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.

&&

LAT...LON 3410 8304 3411 8303 3415 8306 3417 8310
      3423 8308 3427 8312 3424 8317 3424 8325
      3426 8330 3423 8335 3426 8334 3433 8339
      3439 8339 3458 8316 3448 8303 3437 8297
      3403 8296
TIME...MOT...LOC 0132Z 235DEG 13KT 3432 8334 3420 8327 3397 8326

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1016 PM EDT WED AUG 1 2018

SCZ010>012-019-020245-
Laurens SC-Anderson SC-Abbeville SC-Greenwood SC-
1016 PM EDT WED AUG 1 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN LAURENS...
SOUTHEASTERN ANDERSON...EASTERN ABBEVILLE AND NORTHWESTERN GREENWOOD
COUNTIES UNTIL 1045 PM EDT...

At 1016 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles northwest of Abbeville, moving northeast at 25 mph.

Locations to be impacted include...
Abbeville, Honea Path, Ware Shoals, Due West, Donalds, Cokesbury,
Hodges, Shoals Junction and Antreville.

Wind gusts up to 50 mph and 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.

&&

LAT...LON 3424 8259 3451 8236 3451 8235 3450 8234
      3450 8233 3448 8232 3449 8231 3434 8211
      3411 8243
TIME...MOT...LOC 0216Z 222DEG 21KT 3423 8246

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1024 PM EDT WED AUG 1 2018

SCZ011-020300-
Abbeville SC-
1024 PM EDT WED AUG 1 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN ABBEVILLE COUNTY
UNTIL 1100 PM EDT...

At 1023 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles southwest of Abbeville, or near Lake Strom Thurmond, moving
northeast at 20 mph.

Locations to be impacted include...
Abbeville, Calhoun Falls and Lake Russell.

Wind gusts up to 40 mph and 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.

&&

LAT...LON 3406 8263 3429 8252 3415 8224 3408 8231
      3406 8234 3406 8244 3408 8248 3407 8250
      3407 8253 3402 8259
TIME...MOT...LOC 0223Z 209DEG 18KT 3401 8253

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1049 PM EDT WED AUG 1 2018

SCZ006-010>012-019-020315-
Laurens SC-Anderson SC-Abbeville SC-Greenwood SC-
Greater Greenville SC-
1049 PM EDT WED AUG 1 2018

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL LAURENS...SOUTH
CENTRAL GREENVILLE...EAST CENTRAL ANDERSON...NORTHEASTERN ABBEVILLE
AND NORTHWESTERN GREENWOOD COUNTIES UNTIL 1115 PM EDT...

At 1048 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles north of Abbeville, or near Donalds, moving north at 20 mph.

Locations to be impacted include...
Honea Path, Ware Shoals, Due West, Donalds, Shoals Junction,
Princeton and Hickory Tavern.

Wind gusts up to 40 mph and 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.

&&

LAT...LON 3429 8231 3435 8252 3465 8244 3455 8213
TIME...MOT...LOC 0248Z 200DEG 16KT 3439 8239

HG