Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
251 PM EDT TUE JUN 14 2016

.SYNOPSIS...
Warm and humid conditions are expected through the end of the work
week. A cold front will push across the region on Friday, with dry
and cooler high pressure arriving this weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 240 PM: A weak frontal boundary remains essentially stationary
across the CWFA, dividing hot and very humid subtropical air
from notably drier continental air. This boundary can be seen on
satellite as the northern edge of a Cu field. Southerly flow is
expected to push the boundary north again overnight. Meanwhile, an
upper ridge is seen over the mid-eastern CONUS. A weak shortwave
trough is moving through the ridge, across the Gulf states,
and will move over the Carolinas Wednesday morning. Storms along
and south of the boundary will pose a threat of damaging wind,
mainly on account of SBCAPEs near 2000 J/kg and high DCAPEs well
over 1000 J/kg. Shear is relatively weak but may allow storms to
grow into clusters. SPC has expanded the Marginal Risk in their
Day 1 outlook to cover most of the Upstate.

Confidence in the overnight forecast is somewhat limited given
varying degrees of convection featured during the afternoon. It
appears some of the short range guidance, e.g. 4km NAM, depict
"worked-over" profiles by late evening that would not support
additional precip. However, many SREF members show a modest
amount of elevated instability persisting throughout the night,
and something like that would account for the lingering PoPs
suggested by a guidance consensus. That of course assumes some
source of lift. The incoming trough does not have the dynamics to
expect much intiation from it alone, but weak warm upglide could
also have an effect. I'm handling the situation by reflecting
a very slowly decaying PoP trend tonight. Robust thunderstorms
are not expected to last past the loss of the sfc instability,
however. Moist conditions and convective debris will keep temps
several degrees above normal.

The shortwave axis will be entering the CWFA from the west a little
after daybreak. Models generally key on this and rapidly develop
convection in the morning. The wave is trailed by a broad cold
frontal zone, most notable for enhancing low level convergence as it
moves thru the area during the day. CAPE values peaking below those
Tuesday given slightly cooler conditions. Prog soundings are not as
dry, and shear will remain rather weak, so heavy rain may end up
being our most significant threat given PWAT values remaining 1.9
to 2.0 inches over much of the area per NAM. Max temps will not be
as hot, but still 2-3 degrees above normal. Despite sfc dewpoints
expected to exceed those Tuesday, heat indices will be lower.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 145 PM EDT Tuesday...the second half of the week looks
problematic in terms of coverage and strength of deep convection.
The period begins Wednesday evening with lingering showers/storms,
especially over the Piedmont zones. Most of the convection will do
the usual diurnal weakening and be gone by late evening. However,
the models continue to indicate the approach of a wave/vort lobe
from the lower OH valley region after 06Z Thursday. The question is
whether or not this feature will support/drive any thunderstorm
activity south/east of the Ohio River after dark. The model guidance
shows an unstable boundary layer overnight with substantial CAPE,
probably 1000 J/kg or so, across the area to the west of the NC
mountains, which would support keeping convection alive that would
be able to reach the NC mountains in the pre-dawn hours. For that
reason, a chance of precip was retained on the TN border overnight.
Thursday is more of a question, especially in light of the Day 3
slight risk across most of the forecast area. What is interesting
with this part of the forecast is that the operational NAM and
GFS fail to respond with much of any convection on Thursday. In that
regard, the Slight Risk appears to be based on the ingredients seen
in the model guidance, that being a surface boundary dropping down
across the OH valley and toward the Srn Appalachians Thursday
evening, substantial surface-based CAPE ahead of the boundary
(perhaps greater than 2000 J/kg), and what would also be substantial
deep layer shear brought on by a mid-level jetlet. If the
operational models are wrong with their failure to develop storms,
then we could have some kind of severe wind-producing MCS coming at
us from the Cumberland Plateau in the evening hours. An idea worth
letting simmer away on a back burner for now. Precip chances will be
kept modest for the time being for Thursday and Thursday night, and
temps will be seasonally warm. Friday looks a bit less busy and
naturally a bit more uncertain. An upper low dropping down across
the central Appalachians and Mid-Atlantic will help to bring a
surface boundary down across the region during the day. This will
probably take the form as more of a back-door cold front as it wraps
around the mountains. How far the front gets will determine the
extent of precip coverage and the high temps. For now, a chance of
precip is shown across mainly the NC part of the fcst area.  The
temp will be more tricky, perhaps limited to the mid 80s across the
NW Piedmont but still in the mid 90s in northeast GA ahead of the
southward moving front.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
At 230 PM Tuesday: On Friday evening an upper trough will be along
the eastern seaboard, with an upper low moving reaching the NC
coast. The GFS closes off this low near the SC coast by Sunday
evening, while the ECMWF closes off a deeper low off the northeast
NC coast. The GFS low moves to western FL by Sunday evening, while
while the ECMWF low remains in the vicinity of the NC Outer Banks.
By Monday evening the weakening GFS low reaches the AL coast, while
hte stronger ECMWF low moves up the Gulf Stream east of NJ. By mid
week, the models solutions diverge, with the GFS showing a
reamplfied and retrogresses low over the eastern USA, and the ECMWF
showing zonal flow over the same area.

At the surface: On Friday evening high pressure will set up along
the east slopes of the southern Appalachians in the wake of a cold
front, and will linger into Sunday. By Monday a northward return
of the front will allow precipitation to spread inland towards the
mountains, and this pattern persists into Tuesday. Temperatures will
run slightly below normal until Tuesday, when the rise above normal.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
At KCLT: Midday visible satellite imagery shows a line of enhanced
Cu stretching acrs the immediate vcnty of KCLT, highlighting
the position of a stationary front. This front is expected to
gradually shift northward this aftn, bringing warmer and more moist
air over the field. Regardless of whether a shower develops along
the front itself, a round of convection will be most likely in the
late afternoon with heating and destabilization. A TEMPO has been
retained to cover these possibilities, but some SHRA or even TSRA
could recur later in the evening. The longer initiation is delayed,
the later into the evening the activity could last, as the energy
could be realized by an advancing (but weak) shortwave. With the
front expected to move north, a southerly wind shift is expected,
and low stratus are not likely to develop with only very weak
warm upglide occurring. A chance of diurnally driven convection
does exist tomorrow, and overall will be higher than today, so a
PROB30 has already been included late in the period.

Elsewhere: Trends mostly as at KCLT. Anywhere south of the frontal
boundary will have at least a small chance of seeing TSRA this
afternoon and evening. Chances warrant a TEMPO at all terminals
except KHKY, which is expected to remain on the cool/north side
until tonight. Smaller chances of mainly just light precipitation
do persist overnight, though if widespread convection develops and
diminishes diurnally (early evening) the advancing trough may not
be able to produce much further activity. Though very moist sfc
conditions will be in place south of the front tonight, low level
profiles are not supportive of dense fog or low stratus, so VFR is
expected. That said, some ground fog could develop particularly
in areas where rain falls this aftn. Unstable conditions and SCT
SHRA/TSRA are expected to ramp up again late Wed mrng.

Outlook...Mostly VFR conditions are expected, except for possible
valley fog in the NC MTNS each morning. Coverage is expected to be
more isolated for Thursday and Friday in the wake of a departing
trough.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     High 100%     High 100%     High  98%
KGSP       High 100%     High 100%     High  94%     High  98%
KAVL       High 100%     High  97%     High  91%     High  97%
KHKY       High 100%     High 100%     High  91%     High  94%
KGMU       High 100%     High 100%     High  94%     High 100%
KAND       High 100%     High 100%     High  96%     High 100%

The percentage reflects the number of guidance members agreeing
with the schedule 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

&&

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

&&

SYNOPSIS...JAT
NEAR TERM...Wimberley
SHORT TERM...PM
LONG TERM...JAT
AVIATION...Wimberley

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
957 AM EDT TUE JUN 14 2016

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-151400-
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-
957 AM EDT TUE JUN 14 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON.
ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE CLOUD-
TO-GROUND LIGHTNING AND GUSTY WINDS. AN ISOLATED STRONG TO
POTENTIALLY SEVERE STORM OR TWO CANNOT BE RULED OUT...WITH THE
MAIN THREAT BEING DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

..WEDNESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..THURSDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..FRIDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..SATURDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..SUNDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..MONDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

07

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
200 PM EDT TUE JUN 14 2016

SCZ010-141845-
ANDERSON SC-
200 PM EDT TUE JUN 14 2016

...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT SOUTH CENTRAL
ANDERSON COUNTY UNTIL 245 PM EDT...

AT 159 PM EDT...DOPPLER RADAR WAS TRACKING A THUNDERSTORM WITH
TORRENTIAL RAINFALL 11 MILES EAST OF HARTWELL...OR NEAR
STARR...MOVING EAST AT 10 MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
IVA AND STARR.

PEA SIZE HAIL...WIND GUSTS UP TO 40 MPH AND TORRENTIAL RAINFALL
RATES UP TO 3 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. DO NOT DRIVE ACROSS
FLOODED ROADS.

&&

LAT...LON 3427 8275 3430 8278 3434 8279 3436 8283
      3442 8258 3433 8256 3432 8257 3426 8266
      3425 8275
TIME...MOT...LOC 1759Z 267DEG 10KT 3433 8273

JMP

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
233 PM EDT TUE JUN 14 2016

SCZ019-141900-
GREENWOOD SC-
233 PM EDT TUE JUN 14 2016

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL GREENWOOD COUNTY
UNTIL 300 PM EDT...

AT 233 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 12
MILES EAST OF GREENWOOD...OR NEAR GREENWOOD STATE PARK...MOVING EAST
AT 10 MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
GREENWOOD STATE PARK...LAKE GREENWOOD AND DYSON.

HALF INCH HAIL AND TORRENTIAL RAINFALL RATES UP TO 3 INCHES PER HOUR
WILL BE POSSIBLE IN THESE AREAS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DIME TO NICKEL SIZE HAIL CAN CAUSE CONSIDERABLE DAMAGE TO VEHICLES.
CONSIDER MOVING VEHICLES TO A COVERED STORAGE AREA BEFORE THE STORM
ARRIVES.

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. DO NOT DRIVE ACROSS
FLOODED ROADS.

&&

LAT...LON 3421 8200 3422 8196 3420 8194 3419 8192
      3418 8192 3418 8191 3416 8191 3416 8190
      3415 8190 3414 8188 3413 8198
TIME...MOT...LOC 1833Z 250DEG 12KT 3418 8193

JMP

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
238 PM EDT TUE JUN 14 2016

GAZ028-SCZ010-141930-
HART GA-ANDERSON SC-
238 PM EDT TUE JUN 14 2016

...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT SOUTHEASTERN
HART AND SOUTH CENTRAL ANDERSON COUNTIES UNTIL 330 PM EDT...

AT 237 PM EDT...DOPPLER RADAR WAS TRACKING A THUNDERSTORM WITH
TORRENTIAL RAINFALL 5 MILES SOUTHEAST OF HARTWELL...MOVING EAST AT 15
MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
NUBERG.

PEA SIZE HAIL AND EXTREME RAINFALL RATES IN EXCESS OF 3 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. DO NOT DRIVE ACROSS
FLOODED ROADS.

&&

LAT...LON 3431 8295 3440 8279 3426 8272 3426 8275
      3427 8275 3429 8278 3428 8281 3427 8282
      3427 8284 3425 8290 3425 8292
TIME...MOT...LOC 1837Z 254DEG 15KT 3429 8288

JMP

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
246 PM EDT TUE JUN 14 2016

GAZ010-141915-
RABUN GA-
246 PM EDT TUE JUN 14 2016

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL RABUN COUNTY UNTIL
315 PM EDT...

AT 246 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 6
MILES SOUTH OF CLAYTON...OR OVER LAKEMONT...MOVING NORTHEAST AT 10
MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
CLAYTON...TIGER...LAKE RABUN AND LAKEMONT.

WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE IN THESE AREAS.

LAT...LON 3490 8341 3482 8327 3482 8329 3481 8329
      3482 8331 3481 8330 3480 8330 3480 8331
      3474 8344 3479 8350
TIME...MOT...LOC 1846Z 227DEG 10KT 3479 8342

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
317 PM EDT TUE JUN 14 2016

GAZ010-141930-
RABUN GA-
317 PM EDT TUE JUN 14 2016

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN RABUN COUNTY UNTIL
330 PM EDT...

AT 317 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 6
MILES NORTHEAST OF CLAYTON...OR NEAR SKY VALLEY...MOVING NORTHEAST AT
10 MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
SKY VALLEY.

WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE IN THESE AREAS.

LAT...LON 3500 8333 3500 8328 3496 8318 3490 8330
      3492 8336
TIME...MOT...LOC 1917Z 221DEG 7KT 3494 8331

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
321 PM EDT TUE JUN 14 2016

SCZ019-141945-
GREENWOOD SC-
321 PM EDT TUE JUN 14 2016

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN GREENWOOD COUNTY
UNTIL 345 PM EDT...

AT 321 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 10
MILES SOUTH OF GREENWOOD...OR 7 MILES NORTHEAST OF TROY...MOVING
NORTHEAST AT 10 MPH.

LOCATIONS TO BE IMPACTED INCLUDE...
BRADLEY...KIRKSEY...CALLISON AND PROMISED LAND.

PEA SIZE HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE IN THESE
AREAS.

LAT...LON 3398 8220 3399 8223 3402 8224 3401 8225
      3403 8228 3416 8219 3404 8199 3397 8218
TIME...MOT...LOC 1921Z 221DEG 7KT 3404 8218

LANE