Severe Thunderstorm Warning 101, NWS Greenville-Spartanburg, SC

161 
WWUS52 KGSP 221738
SVSGSP

Severe Weather Statement
National Weather Service Greenville-Spartanburg SC
138 PM EDT Fri May 22 2020

GAC241-SCC073-221800-
/O.CON.KGSP.SV.W.0101.000000T0000Z-200522T1800Z/
Rabun GA-Oconee SC-
138 PM EDT Fri May 22 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 200 PM EDT
FOR NORTHEASTERN RABUN AND NORTHERN OCONEE COUNTIES...

At 138 PM EDT, a severe thunderstorm was located 6 miles northwest of
Walhalla, or near Oconee State Park, moving east at 40 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to trees and power lines.

Locations impacted include...
Walhalla, Salem, Oconee State Park, Mountain Rest, Long Creek, Bad
Creek, Pine Mountain and Lake Keowee.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Scattered trees and power lines will be blown down in the warned
area. Seek shelter inside an interior room.

Please report damaging winds, hail, or flooding to the National
Weather Service Greenville-Spartanburg by calling toll free, 1, 800,
2 6 7, 8 1 0 1, or by posting on our Facebook page, or Tweet it using
hashtag nwsgsp. Your message should describe the event and the
specific location where it occurred.

&&

LAT...LON 3500 8315 3500 8311 3503 8301 3476 8289
      3474 8290 3473 8288 3476 8328 3497 8324
TIME...MOT...LOC 1738Z 266DEG 33KT 3485 8312 

HAIL...<.75IN
WIND...60MPH
 
$$

RM

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1050 AM EDT Fri May 22 2020

.SYNOPSIS...
An upper-level low pressure system just northwest of the region
early this morning will move away to the northeast today. A strong
disturbance rounding the south side of this system will cross the
western Carolinas and northeast Georgia late today. A strengthening
high pressure ridge will then build over the southeast through the
weekend, with warming temperatures but also afternoon and evening
thunderstorms redeveloping each day. The high pressure ridge will
dominate the southeast through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
1030 AM Update...Shallow convec showers and thunderstorms are
crossing into the far wrn zones currently. Not expecting much impact
with these storms outside of periodic cloud-to-ground lightning.
Still anticipating a possibly semi-organized line of storms later
this afternoon associated with a stout upper-level vort lobe. Much
will depend on the amt of instability achieved after more widespread
cloudiness spreads in during the early afternoon.

As of 635 am EDT: The Dense Fog Advisory has been expanded to
Laurens SC and Union NC through 9 am. There continues to be a race
ongoing between visibility crashing in dense fog due to the abundant
low level moisture, and mid-level clouds arriving from the west
ahead of the leading edge of the upper level forcing. There should
be a slightly longer period of areas of dense fog across the western
NC foothills and piedmont, as well as the eastern Upstate of SC,
east of a Spartanburg to Laurens line, before the clouds spill in to
improve the visibility. A dense fog advisory remains in effect for
these areas through 9 am, while an SPS has been featured for
mountain river valley fog.

Otherwise, water vapor imagery shows a deep, closed low pressure
system slowly filling over upper portions of the Ohio River Valley
early this morning. After the low clouds and fog burn off mid to
late morning, heating and instability will rebound quickly through
the afternoon hours. As the upper jetlet associated with the upper
low lifts northeast today, improving upper divergence will cross the
western Carolinas during the afternoon and evening hours. In
addition, embedded H5 vorticity lobes south of the departing upper
low will cross the heart of the forecast area from 18Z this
afternoon through about 03Z this evening. This should provide plenty
of forcing for convection during the afternoon and evening hours.
Mid-level lapse rates should increase to about 6.5 deg C/km, SBCAPE
values should rise above 2000 J/kg, especially over the southern
half of the forecast area. Sfc to 3 km shear values should reach 40
to 45 kt late in the day and likely peak near I-77 by early evening.
The marginal severe threat thus appears warranted across the
forecast area, with perhaps the greatest risk near the I-85 corridor
where instability and shear will best overlap to produce a damaging
wind/isolated tornado threat.

The filling upper low will lift steadily away through the Mid-
Atlantic tonight, with a shallow upper ridge beginning to build over
the southern Appalachians. Showers could persist into the nighttime
hours given the lingering low-level moisture, but thunder chances
will steadily diminish with the loss of instability and departing
upper forcing. Anticipate a smaller than climo diurnal range on
temps through the near term.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 330 am EDT Friday: A 500 mb ridge axis will strengthen over
the southeast through the weekend, with 585 dm heights on Saturday
rising to 586 dm by Sunday afternoon. With the ridge axis setting up
just west of the mountains Saturday afternoon, there is some
potential for upstream convection to ride down the ridge and across
the northern tier of the forecast area late in the day. Piedmont
locations should see 2500 J/kg of sbCAPE late day with heating, plus
the northern tier could experience 30+ kt of shear. Timing any MCS
development or movement will be challenging, so the forecast will
follow mainly a diurnal peak with instability, especially with lapse
rates steepening up over the mountains Saturday afternoon.

With capping under the ridge still fairly limited through late
weekend, ridge top convection will likely develop again with heating
Sunday afternoon. SBCAPE values should rebound to 2000+ again late
in the day, and a surface backdoor cold front may approach from the
northeast very late Sunday. Steering flow will be quite weak on
Sunday, meaning any convection could pose local hydro issues from
slowly moving storms. Anticipate max temps rising to some 5 to 10
degrees above climo through the weekend.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 330 AM Friday: A blocky, amplified pattern will develop across
the CONUS thru the medium range, as an upper ridge closes off over
the Mid-Atlantic, while an upper low develops over the Southern
Plains. This will keep a persistent easterly to southeasterly deep-
layer flow atop the forecast area thru most of next week. This
results in slightly above normal temps, despite plenty of cloudiness
from persistent Atlantic moisture fetch across the region. Generally
isolated to scattered diurnal convection is expected each day,
especially in the high terrain, as we enter more typical late-spring
pulse convective season. The higher PWAT plume will stay west of the
area, so heavy rain threat should be localized to slow-moving or
training convection. Severe threat looks isolated.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: Abundant low-level moisture, and the slow
arrival of higher clouds from the west, are conspiring to create
plenty of LIFR to VLIFR vsby and cigs around the region. However,
lower restrictions remain a bit spotty at all the TAF sites except
KHKY, which will see solid VLIFR through 14Z. KCLT and KAVL should
have a TEMPO window of LIFR conditions, with the Upstate TAF sites
being much patchier with any morning IFR restrictions. Will then
time the afternoon convection with the arriving upper support
starting early to mid afternoon at western sites and running well
into the evening hours across KCLT, with gusty winds in the
TEMPO/PROB groups. Expect light winds this morning to become more SW
today, with low end gusts possible at times from the Upstate to KCLT.

Outlook: Afternoon to evening showers and thunderstorms will be
possible over the weekend and into early next week. Restrictions are
also possible each morning from low clouds and fog and again later
in the day under any thunderstorms.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High  98%     High 100%     High 100%     High  85%
KGSP       High  86%     High 100%     High 100%     High 100%
KAVL       High  83%     High  83%     High 100%     Low   57%
KHKY       High 100%     High  88%     High  88%     Low   49%
KGMU       Med   75%     High  98%     High 100%     High 100%
KAND       Med   75%     High 100%     High 100%     High 100%

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...HG/SBK
SHORT TERM...HG
LONG TERM...ARK
AVIATION...HG

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
555 AM EDT Fri May 22 2020

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-SCZ001>006-
010-011-019-231000-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Graham-Northern Jackson-Macon-
Southern Jackson-Transylvania-Henderson-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Anderson-Abbeville-Greenwood-
555 AM EDT Fri May 22 2020

This Hazardous Weather Outlook is for northeast Georgia, the
mountains of western North Carolina, and the western Upstate of
South Carolina.

.DAY ONE...Today and tonight.

Thunderstorms will develop from the west this afternoon and evening.
Cloud to ground lightning and locally heavy rainfall can be expected
with any of these thunderstorms. The thunderstorms may also produce
very gusty winds, and damaging gusts to 60 mph will be possible in a
few storms. An isolated tornado will be possible as well, especially
for locations near, or southeast of, the Interstate 85 corridor.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

NCZ035>037-056-057-068>072-082-501>510-SCZ007>009-012>014-231000-
Alexander-Iredell-Davie-Catawba-Rowan-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-
Spartanburg-Cherokee-York-Laurens-Union SC-Chester-
555 AM EDT Fri May 22 2020

...DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM EDT THIS MORNING...

This Hazardous Weather Outlook is for the foothills and Piedmont of
western North Carolina, as well as the eastern Upstate of 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.

   Dense Fog Advisory.

Thunderstorms will develop from the west this afternoon and evening.
Cloud to ground lightning and locally heavy rainfall can be expected
with any of these thunderstorms. The thunderstorms may also produce
very gusty winds, and damaging gusts to 60 mph will be possible in a
few storms. An isolated tornado will be possible as well, especially
for locations near, or southeast of, the Interstate 85 corridor.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
107 PM EDT Fri May 22 2020

GAZ010-NCZ062>064-SCZ001-002-004-221745-
Rabun GA-Transylvania NC-Southern Jackson NC-Macon NC-
Pickens Mountains SC-Greater Oconee SC-Oconee Mountains SC-
107 PM EDT Fri May 22 2020

...A STRONG THUNDERSTORM WILL IMPACT RABUN...SOUTHEASTERN MACON...
SOUTHWESTERN TRANSYLVANIA...SOUTHEASTERN JACKSON...NORTHWESTERN
PICKENS AND OCONEE COUNTIES UNTIL 145 PM EDT...

At 106 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southwest of Clayton, or near Tiger, moving east at 40 mph.

Locations to be impacted include...
Seneca, Walhalla, Clayton, Highlands, Mountain City, Tiger, Dillard,
Sky Valley, Cashiers and Salem.

Wind gusts up to 50 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

Doppler radar indicates weak rotation with this storm. Spin-up of a
very brief, weak tornado cannot be ruled out. Be prepared to take
immediate action if a tornado is sighted or a Tornado Warning is
issued.

LAT...LON 3517 8285 3482 8287 3481 8289 3478 8288
      3474 8290 3474 8288 3468 8288 3471 8335
      3473 8338 3473 8341 3475 8343 3473 8348
      3474 8352 3499 8355 3500 8348 3500 8352
      3502 8352 3504 8356 3506 8356
TIME...MOT...LOC 1706Z 266DEG 33KT 3483 8345

RM